 CHAPTER 1 OF THE PROBLEMS OF PHILLOSOPHY In the following pages I have confined myself in the main to those problems of philosophy in regard to which I thought it possible to say something positive and constructive since merely negative criticism seemed out of place. For this reason, theory of knowledge occupies a larger space than metaphysics in the present volume and some topics much discussed by philosophers are treated very briefly, if at all. I have derived valuable assistance from unpublished writings of G. E. Moore and J. M. Keynes from the former as regards the relations of sense data to physical objects and from the latter as regards probability and induction. I have also profited greatly by the criticisms and suggestions of Professor Gilbert Murray. CHAPTER 1. APPEARANCE IN REALITY Is there any knowledge in the world which is so certain that no reasonable man could doubt it? This question, which at first sight might not seem difficult, is really one of the most difficult that can be asked. When we have realized the obstacles in the way of a straightforward and confident answer, we shall be well launched on the study of philosophy. For philosophy is merely the attempt to answer such ultimate questions, not carelessly and dogmatically as we do in ordinary life and even in the sciences, but critically, after exploring all that makes such questions puzzling and after realizing all the vagueness and confusion that underlie our ordinary ideas. In daily life, we assume as certain many things which, on a closer scrutiny, are found to be so full of apparent contradictions that only a great amount of thought enables us to know what it is that we really may believe. In the search for certainty, it is natural to begin with our present experiences, and in some sense, no doubt, knowledge is to be derived from them. But any statement as to what it is that our immediate experiences make us know is very likely to be wrong. It seems to me that I am now sitting in a chair, at a table of a certain shape, on which I see sheets of paper with writing or print. By turning my head, I see out of the window buildings and clouds in the sun. I believe that the sun is about 93 million miles from the earth, that it is a hot globe many times bigger than the earth, that owing to the earth's rotation, it rises every morning, and will continue to do so for an indefinite time in the future. I believe that, if any other normal person comes into my room, he will see the same chairs and tables and books and papers as I see, and that the table which I see is the same as the table which I feel pressing against my arm. All this seems to be so evident as to be hardly worth stating, except an answer to a man who doubts whether I know anything. Yet all this may be reasonably doubted, and all of it requires much careful discussion before we can be sure that we have stated it in a form that is wholly true. To make our difficulties plain, let us concentrate attention on the table. To the eye it is oblong, brown, and shiny. To the touch it is smooth, and cool, and hard. When I tap it, it gives out a wooden sound. Anyone else who sees and feels and hears the table will agree with this description, so that it might seem as if no difficulty would arise. But as soon as we try to be more precise, our troubles begin. Although I believe that the table is really of the same color all over, the parts that reflect the light look much brighter than the other parts, and some parts look white because of reflected light. I know that, if I move, the parts that reflect the light will be different, so that the apparent distribution of colors on the table will change. It follows that, if several people are looking at the same table at the same moment, no two of them will see exactly the same distribution of colors, because no two can see it from exactly the same point of view. And any change in the point of view makes some change in the way the light is reflected. For most practical purposes, these differences are unimportant, but to the painter they are all important. The painter has to unlearn the habit of thinking that things seem to have the color which common sense says they really have, and to learn the habit of seeing things as they appear. Here we have already the beginning of one of the distinctions that caused most trouble in philosophy, the distinction between appearance and reality, between what things seem to be and what they are. The painter wants to know what things seem to be, the practical man and the philosopher want to know what they are, but the philosophers wish to know this is stronger than the practical man's, and is more troubled by knowledge as to the difficulties of answering the question. To return to the table. It is evident from what we have found, that there is no color which preeminently appears to be the color of the table, or even of any one particular part of the table. It appears to be of different colors from different points of view, and there is no reason for regarding some of these as more really its color than others. And we know that even from a given point of view, the color will seem different by artificial light, or to a color blind man, or to a man wearing blue spectacles, while in the dark there will be no color at all, though to touch and hearing the table will be unchanged. This color is not something which is inherent in the table, but something depending upon the table and the spectator, and the way the light falls on the table. When in ordinary life we speak of the color of the table, we only mean the sort of color which it will seem to have to a normal spectator from an ordinary point of view under usual conditions of light. But the other colors which appear under other conditions have just as good a right to be considered real, and therefore to avoid favoritism we are compelled to deny that, in itself the table has any one particular color. The same thing applies to the texture. With the naked eye one can see the grain, but otherwise the table looks smooth and even. If we looked at it through a microscope we should see roughnesses and hills and valleys and all sorts of differences that are imperceptible to the naked eye. Which of these is the real table? We are naturally tempted to say that what we see through the microscope is more real, but that in turn would be changed by a still more powerful microscope. If then we cannot trust what we see with the naked eye, why should we trust what we see through a microscope? Thus, again, the confidence in our senses with which we began deserts us. The shape of the table is no better. We are all in the habit of judging as to the real shapes of things, and we do this so unreflectingly that we come to think we actually see the real shapes. But in fact, as we all have to learn if we try to draw, a given thing looks different in shape from every different point of view. If our table is really rectangular, it will look from almost all points of view, as if it had two acute angles and two obtuse angles. If opposite sides are parallel, it will look as if they converge to a point away from the spectator. If they are of equal length, they will look as if the nearest side were longer. All these things are not commonly noticed in looking at a table because experience has taught us to construct the real shape from the apparent shape. And the real shape is what interests us as practical men. But the real shape is not what we see. It is something inferred from what we see. And what we see is constantly changing in shape as we move about the room. So that, here again, the senses seem not to give us the truth about the table itself, but only about the appearance of the table. Similar difficulties arise when we consider the sense of touch. It is true that the table always gives us a sensation of hardness, and we feel that it resists pressure. But the sensation we obtain depends on how hard we press the table, and also upon what part of the body we press with. Thus the various sensations, due to various pressures or various parts of the body, cannot be supposed to reveal directly any definite property of the table, but at most to be signs of some property which perhaps causes all the sensations, but is not actually apparent in any of them. And the same applies still more obviously to the sounds which can be elicited by wrapping the table. Thus it becomes evident that the real table, if there is one, is not the same as what we immediately experience by sight or touch or hearing. The real table, if there is one, is not immediately known to us at all, but must be an inference from what is immediately known. Hence, two very difficult questions that once arise. Namely, one, is there a real table at all? Two, if so, what sort of object can it be? It will help us in considering these questions to have a few simple terms of which the meaning is definite and clear. Let us give the name of sense data to the things that are immediately known in sensation, such things as colors, sounds, smells, hardnesses, roughnesses, and so on. We shall give the name sensation to the experience of being immediately aware of these things. Thus, whenever we see a color, we have a sensation of the color, but the color itself is a sense datum, not a sensation. The color is that of which we are immediately aware, and the awareness itself is the sensation. It is plain that if we are to know anything about the table, it must be by means of the sense data, brown color, oblong shapes, smoothness, etc., which we associate with the table. But for the reasons which have been given, we cannot say that the table is the sense data, or even that the sense data are directly properties of the table. Thus a problem arises as to the relation of the sense data to the real table, supposing there is such a thing. The real table, if it exists, we will call a physical object. Thus we have to consider the relation of the sense data to physical objects. The collection of all physical objects is called matter. Thus our two questions may be restated as follows. One, is there any such thing as matter? Two, if so, what is its nature? The philosopher who first brought prominently forward the reasons for regarding the immediate objects of our senses as not existing independently of us was Bishop Berkeley, 1685-1753. His three dialogues between Hylas and Philonoas, in opposition to skeptics and atheists, undertake to prove that there is no such thing as matter at all, and that the world consists of nothing but minds and their ideas. Hylas has hitherto believed in matter, but he has no match for Philonoas, who mercilessly drives him into contradictions and paradoxes and makes his own denial of matter seem in the end as if it were almost common sense. The arguments employed are of very different value. Some are important in sound, others are confused or quibbling. But Berkeley retains the merit of having shown that the existence of matter is capable of being denied without absurdity, and that if there are any things that exist independently of us, they cannot be the immediate objects of our sensations. There are two different questions involved when we ask whether matter exists, and it is important to keep them clear. We commonly mean by matter, something which is opposed to mind, something which we think of as occupying space, and as radically incapable of any sort of thought or consciousness. It is chiefly in this sense that Berkeley denies matter. That is to say, he does not deny that the sense data which we commonly take as signs of the existence of the table are really signs of the existence of something independent of us, but he does deny that this something is non-mental, that it is neither mind nor ideas entertained by some mind. He admits that there must be something which continues to exist when we go out of the room or shut our eyes, and that what we call seeing the table does really give us reason for believing in something which persists even when we are not seeing it. But he thinks that this something cannot be radically different in nature from what we see, and cannot be independent of seeing altogether, though it must be independent of our seeing. He has thus led to regard the real table as an idea in the mind of God. Such an idea has the required permanence and independence of ourselves without being, as matter would otherwise be, something quite unknowable, in the sense that we can only infer it, and can never be directly and immediately aware of it. Other philosophers since Berkeley have also held that, although the table does not depend for its existence upon being seen by me, it does depend upon being seen, or otherwise apprehended in sensation, by some mind, not necessarily the mind of God, but more often the whole collective mind of the universe. This they hold, as Berkeley does, chiefly because they think there can be nothing real, or at any rate nothing known to be real, except minds and their thoughts and feelings. We might state the argument by which they support their view in some such way as this. Whatever can be thought of is an idea in the mind of the person thinking of it. Therefore, nothing can be thought of except ideas and minds. Therefore, anything else is inconceivable, and what is inconceivable cannot exist. Such an argument, in my opinion, is fallacious, and of course those who advance it do not put it so shortly or so crudely. But whether valid or not, the argument has been very widely advanced in one form or another, and very many philosophers, perhaps a majority, have held that there is nothing real except minds and their ideas. Such philosophers are called idealists. When they come to explaining matter, they either say, like Berkeley, that matter is really nothing but a collection of ideas, or they say, like Leibniz, 1646-1716, that what appears as matter is really a collection of more or less rudimentary minds. But these philosophers, though they deny matter as opposed to mind, nevertheless in another sense admit matter. It will be remembered that we ask two questions, namely, one, is there a real table at all? Two, if so, what sort of object can it be? Now both Berkeley and Leibniz admit that there is a real table, but Berkeley says it is certain ideas in the mind of God, and Leibniz says it is a colony of souls. Thus both of them answer our first question in the affirmative, and only diverge from the views of ordinary mortals in their answer to our second question. In fact, almost all philosophers seem to be agreed that there is a real table. They almost all agree that, however much our sense data, color, shapes, moodness, etc., may depend upon us, yet their occurrence is a sign of something existing independently of us, something differing perhaps completely from our sense data, and yet to be regarded as causing those sense data whenever we are in a suitable relation to the real table. Now obviously this point in which the philosophers are agreed, the view that there is a real table, whatever its nature may be, is vitally important, and it will be worthwhile to consider what reasons there are for accepting this view before we go on to the further question as to the nature of the real table. Our next chapter, therefore, will be concerned with the reasons for supposing that there is a real table at all. Before we go farther, it will be well to consider for a moment what it is that we have discovered so far. It has appeared that, if we take any common object or the sort that is supposed to be known by the senses, what the senses immediately tell us is not the truth about the object as it is apart from us, but only the truth about certain sense data, which so far as we can see, depend upon the relations between us and the object. Thus what we directly see and feel is merely appearance, which we believe to be a sign of some reality behind. But if the reality is not what appears, have we any means of knowing whether there is any reality at all? And if so, have we any means of finding out what it is like? Such questions are bewildering, and it is difficult to know that even the strangest hypotheses may not be true. Thus our familiar table, which is roused by the slightest thoughts in us hither too, has become a problem full of surprising possibilities. The one thing we know about it is that it is not what it seems. Beyond this modest result, so far, we have the most complete liberty of conjecture. Leibniz tells us it is a community of souls. Berkeley tells us it is an idea in the mind of God. Sober science, scarcely less wonderful, tells us that it is a vast collection of electric charges in violent motion. Among these surprising possibilities, doubt suggests that perhaps there is no table at all. Philosophy, if it could not answer so many questions as we could wish, has at least the power of asking questions which increase the interest of the world, and show the strangeness and wonder lying just below the surface, even in the commonest things of daily life. Chapter 2 of The Problems of Philosophy This is a LibriVox recording. All LibriVox recordings are in the public domain. For more information or to volunteer, please visit LibriVox.org. The Problems of Philosophy by Bertrand Russell Chapter 2 The Existence of Matter In this chapter, we have to ask ourselves whether in any sense at all there is such a thing as matter. Is there a table which has a certain intrinsic nature and continues to exist when I am not looking? Or is the table merely a product of my imagination? A dream table in a very prolonged dream. This question is of the greatest importance. For if we cannot be sure of the independent existence of objects, we cannot be sure of the independent existence of other people's bodies. And therefore, still less of other people's minds, since we have no grounds for believing in their minds, except such as are derived from observing their bodies. Thus, if we cannot be sure of the independent existence of objects, we shall be left alone in a desert. It may be that the whole outer world is nothing but a dream, and that we alone exist. This is an uncomfortable possibility, but although it cannot be strictly proved to be false, there is not the slightest reason to suppose that it is true. In this chapter, we have to see why this is the case. Before we embark upon doubtful matters, let us try to find some more or less fixed point from which to start. Although we are doubting the physical existence of the table, we are not doubting the existence of the sense data which made us think there was a table. We are not doubting that while we look, a certain color and shape appear to us, and while we press, a certain sensation of hardness is experienced by us. All this, which is psychological, we are not calling in question. In fact, whatever else may be doubtful, some at least of our immediate experiences seem absolutely certain. Descartes 1596-1615, the founder of modern philosophy, invented a method which may still be used with profit, the method of systematic doubt. He determined that he would believe nothing which he did not see quite clearly and distinctly to be true. Whatever he could bring himself to doubt, he would doubt, until he saw reason for not doubting it. By applying this method, he gradually became convinced that the only existence of which he could be quite certain was his own. He imagined a deceitful demon who presented unreal things to his senses in the perpetual phantasmagoria. It might be very improbable that such a demon existed, but still it was possible, and therefore, doubt concerning things perceived by the senses was possible. But doubt concerning his own existence was not possible. For if he did not exist, no demon could deceive him. If he doubted, he must exist. If he had any experiences whatever, he must exist. Thus his own existence was an absolute certainty to him. I think, therefore I am, he said. Kogito ergo sum. And on the basis of this certainty, he said to word to build up again the world of knowledge which his doubt had laid in ruins. By inventing the method of doubt and by showing that subjective things are the most certain, Descartes performed a great service to philosophy. And one which makes him still useful to all students of the subject. But some care is needed in using Descartes argument. I think, therefore I am, says rather more than is strictly certain. It might seem as though we were quite sure of being the same person today as we were yesterday. And this is no doubt true in some sense. But the real self is as hard to arrive at as the real table. And does not seem to have that absolute convincing certainty that belongs to particular experiences. When I look at my table and see a certain brown color, what is quite certain at once is not I'm seeing a brown color, but rather a brown color is being seen. This of course involves something or somebody, which or who sees the brown color. But it does not of itself involves that more or less permanent person whom we call I. So far as immediate certainty goes, it might be that the something which sees the brown color is quite momentary and not the same as the something which has some different experience the next moment. Thus, it is our particular thoughts and feelings that have primitive certainty. And this applies to dreams and hallucinations as well as to normal perceptions. When we dream or see a ghost, we certainly do have the sensations we think we have. But for various reasons, it is held that no physical object corresponds to these sensations. Thus, the certainty of our knowledge of our own experiences does not have to be limited in any way to allow for exceptional cases. Here, therefore, we have for what it is worth a solid basis from which to begin our pursuit of knowledge. The problem we have to consider is this. Granted that we are certain of our own sense data, have we any reason for regarding them as signs of the existence of something else, which we can call the physical object. When we have enumerated all the sense data, which we should naturally regard as connected with the table, have we said all there is to say about the table? Or is there still something else, something not a sense data, something which persists when we go out of the room? Common sense unhesitatingly answers that there is. What can be bought and sold and pushed about and have a clock laid on it, and so on, cannot be a mere collection of sense data. If the clock completely hides the table, we shall derive no sense data from the table. And therefore, if the table were merely sense data, it would have ceased to exist, and the clock would be suspended in empty air, resting biomerical in the place where the table formerly was. This seems plainly absurd, but whoever wishes to become a philosopher must learn not to be frightened by absurdities. One great reason why it is felt that we must secure a physical object in addition to the sense data is that we want the same object for different people. When 10 people are sitting around a dinner table, it seems preposterous to maintain that they are not seeing the same tablecloth, the same knives and forks and spoons and glasses. But the sense data are private to each separate person. What is immediately present to the sight of one is not immediately present to the sight of another. They all see things from slightly different points of view, and therefore see them slightly differently. Thus, if there are to be public neutral objects, which can be in some sense known to many different people, there must be something over and about the private and particular sense data which appeared to various people. What reason then have we for believing that there are such public neutral objects? The first answer that naturally occurs to one is that although different people may see the table slightly differently, still they all see more or less similar things when they look at the table. And the variations in what they see follow the laws of perspective and reflection of life, so that it is easy to arrive at a permanent object underlying all the different people's sense data. I bought my table from the former occupant of my room. I could not buy his sense data, which died when he went away, but I could and did buy the confident expectation of more or less similar sense data. Thus, it is the fact that different people have similar sense data, and that one person in a given place at different times has similar sense data, which makes us suppose that over and above the sense data, there is a permanent public object which underlies or causes the sense data of various people at various times. Now and so far as the above considerations depend upon supposing that there are other people besides ourselves, they beg the very question at issue. Other people are represented to me by certain sense data, such as the sight of them or the sound of their voices. And if I had no reason to believe that there were physical objects independent of my sense data, I should have no reason to believe that other people exist except as part of my dream. Thus, when we are trying to show that there must be objects independent of our own sense data, we cannot appeal to the testimony of other people since this testimony itself consists of sense data and does not reveal other people's experiences unless our own sense data are signs of things existing independently of us. We must therefore, if possible, find in our own purely private experiences characteristics which show or tend to show that there are in the world things other than ourselves and our private experiences. In one sense, it must be admitted that we can never prove the existence of things other than ourselves and our experiences. No logical absurdity results from the hypothesis that the world consists of myself and my thoughts and feelings and sensations and that everything else is mere fancy. In dreams, a very complicated world may seem to be present and yet, on waking, we find it was a delusion. That is to say, we find that the sense data in the dream do not appear to have corresponded with such physical objects as we should naturally infer from our sense data. It is true that when the physical world is assumed, it is possible to find physical causes for the sense data in dreams. A doorbanging, for instance, may cause us to dream of a naval engagement. But although in this case, there is a physical cause for the sense data, there is not a physical object corresponding to the sense data in the way in which an actual naval battle would correspond. There is no logical impossibility in the supposition that the whole of life is a dream, in which we ourselves create all the objects that come before us. But although this is not logically impossible, there is no reason whatever to suppose that it is true. And it is, in fact, a less simple hypothesis, viewed as a means of accounting for the facts of our own life, than the common sense hypothesis that there really are objects independent of us, whose action on us causes our sensations. The way in which simplicity comes in from supposing that there really are physical objects is easily seen. If the cat appears at one moment in one part of the room and at another in another part, it is natural to suppose that it has moved from one to the other, passing over a series of intermediate positions. But if it is merely a set of sense data, it cannot have ever been in any place where I did not see it. Thus, we shall have to suppose that it did not exist at all while I was not looking, but suddenly sprang into being in a new place. If the cat exists, whether I see it or not, we can understand from our own experience how it gets hungry between one meal and the next. But if it does not exist when I am not seeing it, it seems odd that appetite should grow during non-existence as fast as during existence. And if the cat consists only of sense data, it cannot be hungry. Since no hunger, but by own, can be a sense datum to me. Thus, the behavior of the sense data which represents the cat to me, though it seems quite natural when regarded as an expression of hunger, becomes utterly inexplicable when regarded as mere movements and changes of patches of color which are as incapable of hunger as a triangle is of playing football. But the difficulty in the case of the cat is nothing compared to the difficulty in the case of human beings. When human beings speak, that is, when we hear certain noises which we associate with ideas and simultaneously see certain motions of lips and expressions of faith, it is very difficult to suppose that what we hear is not the expression of the thought as we know it would be if we emitted the same sounds. Of course, similar things happen in dreams where we are mistaken as to the existence of other people. But dreams are more or less suggested by what we call waking life and are capable of being more or less accounted for on scientific principles if we assume that there really is a physical world. Thus every principle of simplicity urges us to adopt the natural view that there really are objects other than ourselves and our sense data which have an existence not dependent upon our perceiving them. Of course, it is not my argument that we originally came by our belief in an independent external world. We find this belief ready in ourselves as soon as we begin to reflect. It is what may be called an instinctive belief. We should never have been led to question this belief but for the fact that at any rate in the case of sight it seems as if the sense data itself were instinctively believed to be the independent object. Whereas argument shows that the object cannot be identical with the sense data. This discovery, however, which is not at all paradoxical in the case of case and smell and sound and only slightly so in the case of touch leaves undiminished our instinctive belief that there are objects corresponding to our sense data. Since this belief does not lead to any difficulties but on the contrary tends to simplify and systematize our accounts of our experiences there seems no good reason for rejecting it. We may therefore admit though with a slight doubt derived from dreams that the external world does really exist and is not fully dependent for its existence upon our continuing to perceive it. The argument which has led us to this conclusion is doubtless, less strong than we could wish but it is typical of many philosophical arguments and is therefore worthwhile to consider briefly its general character and validity. All knowledge we find must be built up upon our instinctive beliefs and if these are rejected nothing is left but among our instinctive beliefs some are much stronger than others while many have by habit and association become entangled with other beliefs not really instinctive but falsely supposed to be part of what is believed instinctively. Philosophy should show us the hierarchy of our instinctive beliefs beginning with those we hold most strongly and presenting each as much isolated and as free from irrelevant additions as possible. It should take care to show that in the form in which they are finally set for our instinctive beliefs do not clash but form a harmonious system. There can never be any reason for rejecting one instinctive belief except that it clashes with others thus if they're found to harmonize the whole system becomes worthy of acceptance. It is of course possible that all or any of our beliefs may be mistaken and therefore all ought to be held with at least some slight element of doubt but we cannot have reason to reject a belief except on the ground of some other belief. Hence by organizing our instinctive beliefs and their consequences by considering which among them is most possible if necessary to modify or abandon we can arrive on the basis of accepting as our sole data what we instinctively believe at an orderly systematic organization of our knowledge in which though the possibility of error remains its likelihood is diminished by the interrelation of the parts and by the critical scrutiny which has preceded acquisitions. This function at least philosophy can perform. Most philosophers rightly or wrongly believe that philosophy can do much more than this that it can give us knowledge not otherwise attainable concerning the universe as a whole and concerning the nature of ultimate reality. Whether this be the case or not the more modest function we have spoken of can certainly be performed by philosophy and certainly suffices for those who have once began to doubt the adequacy of common sense to justify the artist and difficult laborers as philosophical problems involve. End of chapter 2 Chapter 3 of The Problems of Philosophy This is a LibriVox recording. All LibriVox recordings are in the public domain. For more information or to volunteer please visit LibriVox.org The Problems of Philosophy by Bertrand Russell Chapter 3 The Nature of Matter In the preceding chapter we agree though without being able to find demonstrative reasons that it is rational to believe that our sense data for example those which we regard as associated with my table are really signs of the existence of something independent of us and our perceptions. That is to say over and above the sensations of color, hardness, noise and so on which make up the appearance of the table to me I assume that there is something else of which these things are appearances. The color ceases to exist if I shut my eyes. The sensation of hardness ceases to exist if I remove my arm from contact with the table. The sound ceases to exist if I cease to wrap the table with my knuckles. But I do not believe that when all these things cease the table ceases. On the contrary I believe that it is because the table exists continuously that all these sense data will reappear when I open my eyes replace my arm and begin again to wrap with my knuckles. The question we have to consider in this chapter is what is the nature of this real table which persists independently of my perception of it. To this question physical science gives an answer somewhat incomplete it is true and in part still very hypothetical but yet deserving of respect so far as it goes. Physical science more or less unconsciously has drifted into the view that all natural phenomena ought to be reduced to motions. Light and heat and sound are all due to wave motions which travel from the body emitting them to the person who sees light or feels heat or hears some. That which has the wave motion is either ether or gross matter but in either case is what the philosopher would call matter. The only properties which science assigns to it are position and space and the power of motion according to the laws of motion. Science does not deny that it may have other properties but if so such other properties are not useful to the man of science and in no way assist him in explaining the phenomena. It is sometimes said that light is a form of wave motion but this is misleading for the light which we immediately see which we know directly by means of our senses is not a form of wave motion but something quite different something which we all know if we are not blind though we cannot describe it so as to convey our knowledge to a man who is blind. A wave motion on the contrary could quite well be described to a blind man since he can acquire a knowledge of space by the sense of touch and he can experience a wave motion by a sea voyage almost as well as we can but this which a blind man can understand is not what we mean by light we mean by light just that which a blind man can never understand and which we can never describe to him now this something which all of us who are not blind know is not according to science really to be found in the outer world it is something caused by the action of certain waves upon the eyes and nerves and brains of the person who sees the light when it is said that light is waves what is really meant is that waves are the physical cause of our sensations of light but light itself the thing which seeing people experience and blind people do not is not supposed by science to form any part of the world that is independent of us and our senses and very similar remarks would apply to other kinds of sensations it is not only colors and sounds and so on that are absent from the scientific world of matter but also space as we get it through sight or touch it is essential to science that its matter should be in a space but the space in which it is cannot be exactly the space we see or feel to begin with space as we see it is not the same as space as we get it by the sense of touch it is only by experience in infancy that we learn how to touch things we see or how to get a sight of things which we feel touching us but the space of science is neutral as between touch and sight thus it cannot be either the space of touch or the space of sight again different people see the same object as of different shapes according to their point of view a circular coin for example though we should always judge it to be circular will look oval unless we are straight in front of it when we judge that it is circular we are judging that it has a real shape which is not its apparent shape but belongs to it intrinsically apart from its appearance but this real shape which is what concerns science must be in a real space not the same as anybody's apparent space the real space is public the apparent space is private to the recipient in different people's private spaces the same object seems to have different shapes thus the real space in which it has its real shape must be different from the private spaces the space of science therefore though connected with the spaces we see and feel is not identical with them and the manner of its connection requires investigation we agreed provisionally that physical objects cannot be quite like our sense data but may be regarded as causing our sensations these physical objects are in the space of science which we may call physical space it is important to notice that if our sensations are to be caused by physical objects there must be a physical space containing these objects and our sense organs and nerves and brain we get a sensation of touch from an object when we are in contact with it that is to say when some part of our body occupies a place in the physical space quite close to the space occupied by the object we see an object roughly speaking when no opaque body is between the object and our eyes in physical space similarly we only hear or smell or taste an object when we are sufficiently near to it or when it touches the tongue or has some suitable position in physical space relatively to our body we cannot begin to state what different sensations we shall derive from a given object under different circumstances unless we regard the object and our body as both in one physical space for it is mainly the relative positions of the object and our body that determine what sensations we shall derive from the object now our sense data are situated in our private spaces either the space of sight or the space of touch or such vaguer spaces as other senses may give us if a science and common sense assume there is one public all embracing physical space in which physical objects are the relative positions of physical objects in physical space must more or less correspond to the relative positions of sense data in our private spaces there is no difficulty in supposing this to be the case if we see on a road one house nearer to us than another our other senses will bear out the view that it is nearer for example it will be reached sooner if we walk along the road other people will agree that the house which looks nearer to us is nearer the ordinance map will take the same view and thus everything points to a spatial relation between the houses corresponding to the relation between the sense data which we see when we look at the houses thus we may assume that there is a physical space in which physical objects have spatial relations corresponding to those which the corresponding sense data have in our private spaces it is this physical space which is dealt with in geometry and assumed in physics and astronomy assuming that there is physical space and that it does correspond to private spaces what can we know about it we can know only what is required in order to secure the correspondence that is to say we can know nothing of what it is like in itself but we can know the sort of arrangement of physical objects which results from their spatial relations we can know for example that the earth and moon and sun are in one straight line during an eclipse though we cannot know what a physical straight line is in itself as we know the look of a straight line in our visual space thus we come to know much more about the relations of distances in physical space than about the distances themselves we may know that one distance is greater than another or that it is along the same straight line as the other but we cannot have that immediate acquaintance with physical distances that we have with distances in our private spaces or with colors or sounds or other sense data we can know all these things about physical space which a man bombed line might know through other people about the space of sight but the kind of things which a man bombed line could never know about the space of sight we also cannot know about physical space we can know the properties of the relations required to preserve the correspondence with sense data but we cannot know the nature of the terms between which the relations hold with regard to time our feeling of duration or of the lapse of time is notoriously an unsafe guide as to the time that has elapsed by the clock times when we are bored or suffering pain pass slowly times when we are agreeably occupied pass quickly and times when we are sleeping pass almost as if they did not exist thus in so far as time is constituted by duration there is the same necessity for distinguishing a public and a private time as there was in the case of space but in so far as time consists in an order of before and after there is no need to make such a distinction the time order which events seem to have is so far as we can see the same as the time order which they do have at any rate no reason can be given for supposing that the two orders are not the same the same is usually true of space if a regiment of men are marching along a road the shape of the regiment will look different from different points of view but the men will appear arranged in the same order from all points of view hence we regard the order as true also in physical space whereas the shape is only supposed to correspond to the physical space so far as is required for the preservation of the order in saying that the time order which events seem to have is the same as the time order which they really have it is necessary to guard against a possible misunderstanding it must not be supposed that the various states of different physical objects have the same time order as the sense data which constitute the perception of those objects considered as physical objects the thunder and lightning are simultaneous that is to say the lightning is simultaneous with the disturbance of the air in the place where the disturbance begins namely where the lightning is but the sense stadium which we call hearing the thunder does not take place until the disturbance of the air has traveled as far as to where we are similarly it takes about eight minutes for the sun's light to reach us thus when we see the sun we are seeing the sun of eight minutes ago so far as our sense data afford evidence as to the physical sun they afford evidence as to the physical sun of eight minutes ago if the physical sun had ceased to exist within the last eight minutes that would make no difference to the sense data which we call seeing the sun this affords a fresh illustration of the necessity of distinguishing between sense data and physical objects what we have found as regards space is much the same as what we find in relation to the correspondence of the sense data with their physical counterparts if one object looks blue and another red we may reasonably presume that there is some corresponding difference between the physical objects if two objects both look blue we may presume a corresponding similarity but we cannot hope to be acquainted directly with the quality in the physical object which makes it look blue or red science tells us that this quality is a certain sort of wave motion and this sounds familiar because we think of wave motions in the space we see but the wave motions must really be in physical space with which we have no direct acquaintance thus the real wave motions have not that familiarity which we might have supposed them to have and what holds for colors is closely similar to what holds for other sense data thus we find that although the relations of physical objects have all sorts of knowable properties derived from their correspondence with the relations of sense data the physical objects themselves remain unknown in their intrinsic nature so far at least as can be discovered by means of the senses the question remains whether there is any other method of discovering the intrinsic nature of physical objects the most natural though not ultimately the most defensible hypothesis to adopt in the first instance at any rate as regards visual sense data would be that though physical objects cannot for the reasons we have been considering be exactly like sense data yet they may be more or less like according to this view physical objects will for example really have colors and we might by good luck see an object as of the color it really is the color which an object seems to have at any given moment will in general be very similar though not quite the same from many different points of view we might thus suppose the real color to be a sort of medium color intermediate between the various shades which appear from the different points of view such a theory is perhaps not capable of being definitely refuted but it can be shown to be groundless to begin with it is plain that the color we see depends only upon the nature of the light waves that strike the eye and is therefore modified by the medium intervening between us and the object as well as by the manner in which the light is reflective from the object in the direction of the eye the intervening air alters colors unless it is perfectly clear and any strong reflection will alter them completely thus the color we see is a result of the ray as it reaches the eye and not simply a property of the object from which the ray comes hence also provided certain waves reach the eye we shall see a certain color whether the object from which the wave start has any color or not thus it is quite gratuitous to suppose that physical objects have colors and therefore there is no justification for making such a supposition exactly similar arguments will apply to other sense data it remains to ask whether there are any general philosophical arguments enabling us to say that if matter is real it must be of such and such a nature as explained above very many philosophers perhaps most have held that whatever is real must be in some sense mental or at any rate that whatever we can know anything about must be in some sense mental such philosophers are called idealists idealists tell us that what appears as matter is really something mental namely either as lightness held more or less rudimentary minds or as Berkeley contended ideas in the minds which as we should commonly say perceive the matter thus idealists deny the existence of matter as something intrinsically different from mind though they do not deny that our sense data are signs of something which exists independently of our private sensations in the following chapter we shall consider briefly the reasons in my opinion fallacious which idealists advance in favor of their theory End of Chapter 3 Chapter 4 of the Problems of Philosophy This is a LibriVox recording All LibriVox recordings are in the public domain For more information or to volunteer please visit LibriVox.org Recording by Rich Meyers The Problems of Philosophy by Bertrand Russell Chapter 4 Idealism The word idealism is used by different philosophers in somewhat different senses We shall understand by it the doctrine that whatever exists or at any rate whatever can be known to exist must be in some sense mental This doctrine which is very widely held among philosophers has several forms and is advocated on several different grounds The doctrine is so widely held and so interesting in itself that even the briefest survey of philosophy must give some account of it Those who are unaccustomed to philosophical speculation may be inclined to dismiss such a doctrine as obviously absurd There is no doubt that common sense regards tables and chairs and the sun and moon and material objects generally as something radically different from minds and the contents of minds and is having an existence which might continue if minds ceased We think of matter as having existed long before there were any minds and it is hard to think of it as a mere product of mental activity But whether true or false idealism is not to be dismissed as obviously absurd We have seen that even if physical objects do have an independent existence they must differ very widely from sense data and can only have a correspondence with sense data in the same sort of way in which a catalog has a correspondence with the things cataloged Hence common sense leaves us completely in the dark as to the true intrinsic nature of physical objects and if there were good reason to regard them as mental we could not legitimately reject this opinion merely because it strikes us as strange The truth about physical objects must be strange It may be unattainable but if any philosopher believes that he has attained it the fact that what he offers as the truth is strange ought not to be made a ground of objection to his opinion The grounds on which idealism is advocated are generally grounds derived from the theory of knowledge that is to say from a discussion of the conditions which things must satisfy in order that we may be able to know them The first serious attempt to establish idealism on such grounds was that of Bishop Barkley He proved first by arguments which were largely valid that our sense data cannot be supposed to have an existence independent of us but must be impart at least in the mind in the sense that their existence would not continue if there were no seeing or hearing or touching or smelling or tasting So far, his contention was almost certainly valid even if some of his arguments were not so but he went on to argue that sense data were the only things of whose existence our perceptions could assure us and that to be known is to be in a mind and therefore to be mental Hence, he concluded that nothing can ever be known except what is in some mind and that whatever is known without being in my mind must be in some other mind In order to understand his argument it is necessary to understand his use of the word idea He gives the name idea to anything which is immediately known as, for example, sense data are known Thus, a particular color which we see is an idea So is a voice which we hear and so on But the term is not wholly confined to sense data There will also be things remembered or imagined for with such things also we have immediate acquaintance at the moment of remembering or imagining All such immediate data he calls ideas He then proceeds to consider common objects such as a tree, for instance He shows that all we know immediately when we perceive the tree consists of ideas in his sense of the word And he argues that there is not the slightest ground for supposing that there is anything real about the tree except what is perceived Its being, he says, consists in being perceived In the Latin of the schoolmen its essay is per kipi He fully admits that the tree must continue to exist even when we shut our eyes or when no human being is near it But this continued existence, he says, is due to the fact that God continues to perceive it The real tree, which corresponds to what we call the physical object, consists of ideas in the mind of God Ideas more or less like those we have when we see the tree but differing in the fact that they are permanent in God's mind so long as the tree continues to exist All our perceptions according to him consist in a partial participation in God's perceptions and it is because of this participation that different people see more or less the same tree Thus, apart from minds and their ideas there is nothing in the world nor is it possible that anything else should ever be known since whatever is known is necessarily an idea There are in this argument a good many fallacies which have been important in the history of philosophy and which it will be as well to bring to light In the first place, there is a confusion engendered by the use of the word idea We think of an idea as essentially something in somebody's mind and thus when we are told that a tree consists entirely of ideas it is natural to suppose that, if so, the tree must be entirely in minds But the notion of being in the mind is ambiguous We speak of bearing a person in mind not meaning that the person is in our minds but that a thought of him is in our minds When a man says that some business he had to arrange went clean out of his mind he does not mean to imply that the business itself was ever in his mind but only that a thought of the business was formally in his mind but afterwards ceased to be in his mind And so, when Barkley says that the tree must be in our minds if we can know it all that he really has a right to say is that a thought of the tree must be in our minds To argue that the tree itself must be in our minds is like arguing that a person whom we bear in mind is himself in our minds This confusion may seem too gross to have been really committed by any competent philosopher but various attendant circumstances rendered it possible In order to see how it was possible we must go more deeply into the question as to the nature of ideas Before taking up the general question of the nature of ideas we must disentangle two entirely separate questions which arise concerning sense data and physical objects We saw that for various reasons of detail Barkley was right in treating the sense data which constitutes our perception of the tree as more or less subjective in the sense that they depend upon us as much as upon the tree and would not exist if the tree were not being perceived But this is an entirely different point from the one by which Barkley seeks to prove that whatever can be immediately known must be in a mind For this purpose, arguments of detail as to the dependence of sense data upon us are useless It is necessary to prove generally that by being known things are shown to be mental This is what Barkley believes himself to have done It is this question and not our previous question as to the difference between sense data and the physical object that must now concern us Taking the word idea in Barkley's sense there are two quite distinct things to be considered whenever an idea is before the mind There is on the one hand the thing of which we are aware say the color of my table and on the other hand the actual awareness itself the mental act of apprehending the thing The mental act is undoubtedly mental But is there any reason to suppose that the thing apprehended is in any sense mental? Our previous arguments concerning the color did not prove it to be mental They only proved that its existence depends upon the relation of our sense organs to the physical object in our case the table That is to say they proved that a certain color will exist in a certain light if a normal eye is placed at a certain point relatively to the table They did not prove that the color is in the mind of the recipient Barkley's view that obviously the color must be in the mind seems to depend for its plausibility upon confusing the thing apprehended with the act of apprehension Either of these might be called an idea probably either would have been called an idea by Barkley The act is undoubtedly in the mind hence when we are thinking of the act we readily assent to the view that ideas must be in the mind Then forgetting that this was only true when ideas were taken as acts of apprehension we transfer the proposition that ideas are in the mind to ideas in the other sense i.e. to the things apprehended by our acts of apprehension Thus by an unconscious equivocation we arrive at the conclusion that whatever we can apprehend must be in our minds This seems to be the true analysis of Barkley's argument and the ultimate fallacy upon which it rests This question of the distinction between act and object in our apprehending of things is vitally important since our whole power of acquiring knowledge is bound up with it The faculty of being acquainted with things other than itself is the main characteristic of a mind acquaintance with objects essentially consists in a relation between the mind and something other than the mind It is this that constitutes the mind's power of knowing things If we say that the things known must be in the mind we are either unduly limiting the mind's power of knowing or we are uttering a mere tautology We are uttering a mere tautology if we mean by in the mind the same as by before the mind i.e. if we mean merely being apprehended by the mind But if we mean this we shall have to admit that what in this sense is in the mind may nevertheless be not mental Thus when we realize the nature of knowledge Barkley's argument is seen to be wrong in substance as well as in form and his grounds for supposing that ideas i.e. the objects apprehended must be mental are found to have no validity whatever Hence his grounds in favor of idealism may be dismissed It remains to see whether there are any other grounds It is often said, as though it were a self-evident truism that we cannot know that anything exists which we do not know It is inferred that whatever can in any way be relevant to our experience must be at least capable of being known by us Once it follows that, if matter were essentially something with which we could not become acquainted matter would be something which we could not know to exist and which could have for us no importance whatever It is generally also implied for reasons which remain obscure that what can have no importance for us cannot be real and that therefore matter if it is not composed of minds or of mental ideas is impossible and a mere chimera To go into this argument fully at our present stage would be impossible since it raises points requiring a considerable preliminary discussion But certain reasons for rejecting the argument may be noticed at once To begin at the end there is no reason why what cannot have any practical importance for us should not be real It is true that if theoretical importance is included everything real is of some importance to us since as persons desirous of knowing the truth about the universe we have some interest in everything that the universe contains But if this sort of interest is included it is not the case that matter has no importance for us provided it exists even if we cannot know that it exists We can obviously suspect that it may exist and wonder whether it does Hence it is connected with our desire for knowledge and has the importance of either satisfying or thwarting this desire Again, it is by no means a truism and is in fact false that we cannot know that anything exists which we do not know The word know is here used in two different senses One in its first use it is applicable to the sort of knowledge which is opposed to error the sense in which what we know is true the sense which applies to our beliefs and convictions i.e. to what are called judgments In this sense of the word we know that something is the case this sort of knowledge may be described as knowledge of truths Two, in the second use of the word know above the word applies to our knowledge of things which we may call acquaintance This is the sense in which we know sense data the distinction involved is roughly that between Sabois and Conatra in French or between Wiesen and Kennen in German Thus the statement which seemed like a truism becomes when restated the following We can never truly judge that something with which we are not acquainted exists This is by no means a truism but on the contrary a palpable falsehood I have not the honor to be acquainted with the emperor of China but I truly judge that he exists It may be said of course that I judge this because of other people's acquaintance with him This however would be an irrelevant retort since if the principle were true I could not know that anyone else is acquainted with him But further there is no reason why I should not know of the existence of something with which nobody is acquainted This point is important and demands elucidation If I am acquainted with the thing which exists my acquaintance gives me the knowledge that it exists But it is not true that conversely whenever I can know that a thing of a certain sort exists I or someone else must be acquainted with the thing What happens in cases where I have true judgment without acquaintance is that the thing is known to me by description and that in virtue of some general principle the existence of a thing answering to this description can be inferred from the existence of something with which I am acquainted In order to understand this point fully it will be well first to deal with the difference between knowledge by acquaintance and knowledge by description and then to consider what knowledge of general principles if any has the same kind of certainty as our knowledge of the existence of our own experiences These subjects will be dealt with in the following chapters End of chapter four Chapter five of the Problems of Philosophy This is a LibriVox recording All LibriVox recordings are in the public domain For more information or to volunteer please visit LibriVox.org The Problems of Philosophy By Bertrand Russell Chapter five Knowledge by acquaintance and knowledge by description In the preceding chapter we saw that there are two sorts of knowledge knowledge of things and knowledge of truths In this chapter we shall be concerned exclusively with knowledge of things of which in turn we shall have to distinguish two kinds Knowledge of things when it is of the kind we call knowledge by acquaintance is essentially simpler than any knowledge of truths and logically independent of knowledge of truths though it would be rash to assume that human beings ever in fact have acquaintance with things without at the same time knowing some truth about them Knowledge of things by description on the contrary always involves as we shall find in the course of the present chapter some knowledge of truths as its source and ground but first of all we must make clear what we mean by acquaintance and what we mean by description we shall say that we have acquaintance with anything of which we are directly aware without the intermediary of any process of inference or any knowledge of truths thus in the presence of my table I am acquainted with a sense data that make up the appearance of my table its color shape hardness smoothness etc all these are things of which I am immediately conscious when I am seeing and touching my table the particular shade of color that I am seeing may have many things said about it I may say that it is brown that it is rather dark and so on but such statements though they make me know truths about the color do not make me know the color itself any better than I did before so far as concerns knowledge of the color itself as opposed to knowledge of truths about it I know the color perfectly and completely when I see it and no further knowledge of it itself is even theoretically possible thus the sense data which make up the appearance of my table are things with which I have acquaintance things immediately known to me just as they are my knowledge of the table as a physical object on the contrary is not direct knowledge such as it is it is obtained through acquaintance with the sense data that make up the appearance of the table we have seen that it is possible without absurdity to doubt whether there is a table at all whereas it is not possible to doubt the sense data my knowledge of the table is of the kind which we shall call knowledge by description the table is the physical object which causes such and such sense data this describes the table by means of the sense data in order to know anything at all about the table we must know truths connecting it with things with which we have acquaintances we must know that such and such sense data are caused by a physical object there is no state of mind in which we are directly aware of the table all our knowledge of the table is really knowledge of truths and the actual thing which is the table is not strictly speaking known to us at all we know a description and we know that there is just one object to which this description applies though the object itself is not directly known to us in such a case we say that our knowledge of the object is knowledge by description all our knowledge both knowledge of things and knowledge of truths rests upon acquaintance as its foundation it is therefore important to consider what kinds of things there are with which we have acquaintance sense data as we have already seen are among the things with which we are acquainted in fact they supply the most obvious and striking example of knowledge by acquaintance but if they were the sole example our knowledge would be very much more restricted than it is we should only know what it is now present to our senses we could not know anything about the past not even that there was a past nor could we know any truths about our sense data for all knowledge of truths as we shall show demands acquaintance with things which are of and essentially different character from sense data the things which are sometimes called abstract ideas but which we shall call universals we have therefore to consider acquaintance with other things besides sense data if we are to obtain any tolerable adequate analysis of our knowledge the first extension beyond sense data to be considered is acquaintance by memory it is obvious that we often remember that we have seen or heard or had otherwise present to our senses and that in such cases we are still immediately aware of what we remember in spite of the fact that it appears as past and not as present this immediate knowledge by memory is the source of all our knowledge concerning the past without it there could be no knowledge of the past by inference since we should never know that there was anything passed to be inferred the next extension to be considered is acquaintance by introspection we are not only aware of things but we are often aware of being aware of them when i see the sun i am often aware of my seeing the sun thus my seeing the sun is an object with which i have acquaintance when i desire food i may be aware of my desire for food thus my desiring food is an object with which i am acquainted similarly we may be aware of our feeling pleasure or pain and generally of the events which happen in our minds this kind of acquaintance which may be called self-consciousness is the source of all our knowledge of mental things it is obvious that it is only what goes on in our own minds that can be thus known immediately what goes on in the minds of others is known to us through our perception of their bodies that is through the sense data in us which are associated with their bodies but for our acquaintance with the contents of our own minds we should be unable to imagine the minds of others and therefore we could never arrive at the knowledge that they have minds it seems natural to suppose that self-consciousness is one of the things that distinguish men from animals animals we may suppose though they have acquaintance with sense data never become aware of this acquaintance i do not mean that they doubt whether they exist but that they have never become conscious of the fact that they have sensations and feelings nor therefore of the fact that they the subject of their sensations and feelings exist we have spoken of acquaintance with the contents of our minds as self-consciousness but it is not of course consciousness of our self it is consciousness of particular thoughts and feelings the question whether we are also acquainted with our bare selves as opposed to particular thoughts and feelings is a very difficult one upon which it would be rash to speak positively when we try to look into ourselves we always seem to come upon some particular thought or feeling and not upon the i which has the thought or feeling nevertheless there are some reasons for thinking that we are acquainted with the i though the acquaintance is hard to disentangle from other things to make clear what sort of reason there is let us consider for a moment what our acquaintance with particular thoughts really involves when i am acquainted with my seeing the sun it seems plain that i am acquainted with two different things in relation to each other on the one hand there is the sense datum which represents the sun to me on the other hand there is that which sees this sense datum all acquaintance such as my acquaintance with a sense datum which represents the sun seems obviously a relation between the person acquainted and the object with which the person is acquainted when a case of acquaintance is one with which i can be acquainted as i am acquainted with my acquaintance with a sense datum representing the sun it is plain that the person acquainted is myself thus when i am acquainted with my seeing the sun, the whole fact with which I am acquainted is, self acquainted with sense datum. Further, we know the truth, I am acquainted with this sense datum. It is hard to see how we could know this truth or even understand what is meant by it, unless we are acquainted with something which we call, I. It does not seem necessary to suppose that we are acquainted with a more or less permanent person, the same today as yesterday, but it does seem as though we must be acquainted with that thing, whatever its nature, which sees the sun and has acquaintance with a sense data. Thus, in some sense, it would seem we must be acquainted with ourselves as opposed to our particular experiences. But the question is difficult, and complicated arguments can be adduced on either side. Hence, although acquaintance with ourselves seems probably to occur, it is not wise to assert that it undoubtedly does occur. We may therefore sum up as follows what has been said concerning acquaintance with things that exist. We have acquaintance in sensation with the data of the outer senses, and in introspection with the data of what may be called the inner sense, thoughts, feelings, desires, etc. We have acquaintance in memory with things which have been data either of the outer senses or of the inner sense. Whether it is probable, though not certain, that we have acquaintance with self as that which is aware of things or has desires towards things. In addition to our acquaintance with particular existing things, we also have acquaintance with what we shall call universals, that is to say, general ideas such as whiteness, diversity, brotherhood, and so on. Every complete sentence must contain at least one word which stands for a universal, since all verbs have a meaning which is universal. We shall return to universals later on in Chapter 9. For the present it is only necessary to guard against the supposition that whatever we can be acquainted with must be something particular and existent. Awareness of universals is called conceiving, and a universal of which we are aware is called a concept. It will not be seen that among the objects with which we are acquainted are not included physical objects as opposed to sense data nor other people's minds. These things are known to us by what I call knowledge by description which we must now consider. By a description I mean any phrase of the form a so-and-so or the so-and-so. A phrase of the form a so-and-so I shall call an ambiguous description. A phrase of the form the so-and-so in the singular I shall call a definite description. Thus a man is an ambiguous description and the man with the iron mask is a definite description. There are various problems connected with ambiguous descriptions, but I pass them by since they do not directly concern the matter we are discussing, which is the nature of our knowledge concerning objects in cases where we know that there is an object answering to a definite description, though we are not acquainted with any such object. This is a matter which is concerned exclusively with definite descriptions. I shall therefore in the sequel speak simply of descriptions when I mean definite descriptions. Thus a description will mean any phrase of the form the so-and-so in the singular. We shall say that an object is known by description when we know that it is the so-and-so, i.e. when we know that there is one object and no more having a certain property, and it will generally be implied that we do not have knowledge of the same object by acquaintance. We know that the man with the iron mask existed and many propositions are known about him, but we do not know who he was. We know that the candidate who gets the most votes will be elected, and in this case we are very likely also acquainted, in the only sense in which one can be acquainted with someone else, with the man who is in fact the candidate who will get most votes, but we do not know which of the candidates he is, i.e. we do not know any proposition of the form A is the candidate who will get most votes, where A is one of the candidates by name. We shall say that we have merely descriptive knowledge of the so-and-so, when, although we know that the so-and-so exists, and although we may possibly be acquainted with the object which is, in fact, the so-and-so, yet we do not know any proposition A is a so-and-so, where A is something with which we are acquainted. When we say the so-and-so exists, we mean that there is just one object which is the so-and-so. The proposition A is the so-and-so, means that A has the property so-and-so and nothing else has. Mr. A is the Unionist candidate for this constituency, means Mr. A is a Unionist candidate for this constituency and no one else is. The Unionist candidate for this constituency exists, means someone is a Unionist candidate for this constituency and no one else is. Thus, when we are acquainted with an object which is the so-and-so, we know that the so-and-so exists, but we may know that the so-and-so exists when we are not acquainted with any object which we know to be the so-and-so, and even when we are not acquainted with any object which, in fact, is the so-and-so. Common words, even proper names, are usually, really, descriptions. That is to say, the thought in the mind of a person using a proper name correctly can generally only be expressed explicitly if we replace the proper name by a description. Moreover, the description required to express the thought will vary for different people or for the same person at different times. The only thing constant, so long as the name is rightly used, is the object to which the name applies. But so long as this remains constant, the particular description involved usually makes no difference to the truth or falsehood of the proposition in which the name appears. Let us take some illustrations. Suppose some statement made about Bismarck. Assuming that there is such a thing as direct acquaintance with oneself, Bismarck himself might have used his name directly to designate the particular person with whom he was acquainted. In this case, if he made a judgment about himself, he himself might be a constituent of the judgment. Here the proper name has the direct use which it always wishes to have as simply standing for a certain object and not for a description of the object. But if a person who knew Bismarck made a judgment about him, the case is different. What this person was acquainted with were certain sense data which he connected, rightly we will suppose, with Bismarck's body. His body as a physical object and still more his mind were only known as the body and the mind connected with these sense data. That is, they were known by description. It is, of course, very much a matter of chance which characteristics of a man's appearance will come into a friend's mind when he thinks of him. Thus, the description actually in the friend's mind is accidental. The essential point is that he knows that the various descriptions all apply to the same entity in spite of not being acquainted with the entity in question. When we, who did not know Bismarck, make a judgment about him, the description in our minds will probably be some more or less vague mass of historical knowledge, far more in most cases than is required to identify him. But, for the sake of illustration, let us assume that we think of him as the first Chancellor of the German Empire. Here, all the words are abstract except German. The word German will, again, have different meanings for different people. To some, it will recall travels in Germany, to some the look of Germany on the map, and so on. But if we are to obtain a description which we know to be applicable, we shall be compelled at some point to bring in a reference to a particular with which we are acquainted. Such reference is involved in any mention of past, present, and future, as opposed to definite dates, or of here and there, or of what others have told us. Thus, it would seem that, in some way or other, a description known to be applicable to a particular must involve some reference to a particular with which we are acquainted if our knowledge about the thing described is not to be merely what follows logically from the description. For example, the most long lived of men is a description involving only universals, which must apply to some men, but we can make no judgments concerning this men which involve knowledge about him beyond what the description gives. If, however, we say, the first Chancellor of the German Empire was an astute diplomatist, we can only be assured of the truth of our judgment in virtue of something with which we are acquainted, usually a testimony heard or read. Apart from the information we convey to others, apart from the fact about the actual Bismarck which gives importance to our judgment, the thought we really have contains the one or more particulars involved, and otherwise consists wholly of concepts. All names of places, London, England, Europe, the Earth, the Solar System, similarly involve, when used, descriptions which start from someone or more particulars with which we are acquainted. I suspect that even the universe as considered by metaphysics involves such a connection with particulars. In logic, on the contrary, where we are concerned not merely with what does exist but with whatever might or could exist or be, no reference to actual particulars is involved. It would seem that when we make a statement about something only known by description we often intend to make our statement, not in the form involving the description, but about the usual thing described. That is to say, when we say anything about Bismarck we should like, if we could, to make the judgment which Bismarck alone can make, namely the judgment of which he himself is a constituent. In this we are necessarily defeated since the actual Bismarck is unknown to us, but we know that there is an object, B, called Bismarck, and that B was an astute diplomatist. We can thus describe the proposition we should like to affirm, namely, B was an astute diplomatist, where B is the object which was Bismarck. If we are describing Bismarck as the first Chancellor of the German Empire, the proposition we should like to affirm may be described as the proposition asserting concerning the actual object which was the first Chancellor of the German Empire, that this object was an astute diplomatist. What enables us to communicate in spite of the varying descriptions we employ is that we know there is a true proposition concerning the actual Bismarck, and that however we may vary the description, so long as the description is correct, the proposition described is still the same. This proposition which is described and is known to be true is what interests us, but we are not acquainted with the proposition itself, and do not know it, though we know it is true. It will be seen that there are various stages in the removal from acquaintance with particulars. There is Bismarck to people who knew him, Bismarck to those who only know of him through history, the man with the iron mask, the longest lived of men. These are progressively further removed from acquaintance with particulars. The first comes as near to acquaintance as is possible in regard to another person. In the second, we shall still be said to know who Bismarck was. In the third, we do not know who was the man with the iron mask, though we can know many propositions about him which are not logically deducible from the fact that he wore an iron mask. In the fourth, finally, we know nothing beyond what is logically deducible from the definition of the man. There is a similar hierarchy in the region of universals. Many universals, like many particulars, are only known to us by description. But here, as in the case of particulars, knowledge concerning what is known by description is ultimately reducible to knowledge concerning what is known by acquaintance. The fundamental principle in the analysis of propositions containing descriptions is this. Every proposition which we can understand must be composed wholly of constituents with which we are acquainted. We shall not, at this stage, attempt to answer all the objections which may be urged against this fundamental principle. For the present, we shall merely point out that, in some way or other, it must be possible to meet these objections, for it is scarcely conceivable that we can make a judgment or entertain a supposition without knowing what it is that we are judging or supposing about. We must attach some meaning to the words we use if we are to speak significantly and not utter mere noise, and the meaning we attach to our words must be something with which we are acquainted. Thus, when, for example, we make a statement about Julius Caesar, it is plain that Julius Caesar himself is not before our minds since we are not acquainted with him. We have, in mind, some description of Julius Caesar, the man who was assassinated on the Ides of March, the founder of the Roman Empire, or perhaps merely the man whose name was Julius Caesar. In this last description, Julius Caesar is a noise or shape with which we are acquainted. Thus our statement does not mean quite what it seems to mean, but means something involving instead of Julius Caesar, some description of him which is composed wholly of particulars and universals with which we are acquainted. The chief importance of knowledge by description is that it enables us to pass beyond the limits of our private experience. In spite of the fact that we can only know truths which are wholly composed of terms, which we have experienced in acquaintance, we can yet have knowledge by description of things which we have never experienced. In view of the very narrow range of our immediate experience, this result is vital, and until it is understood, much of our knowledge must remain mysterious, and therefore doubtful. End of chapter 5 Knowledge by acquaintance and knowledge by description. Chapter 6 of the Problems of Philosophy. This is a LibriVox recording. All LibriVox recordings are in the public domain. For more information or to volunteer, please visit librivox.org. Recording by Jim Eastman. The Problems of Philosophy by Bertrand Russell Chapter 6 on Induction. In almost all our previous discussions, we have been concerned in the attempt to get clear as to our data in the way of knowledge of existence. What things are there in the universe whose existence is known to us owing to our being acquainted with them. So far our answer has been that we are acquainted with our sense data and probably with ourselves. These we know to exist. And past sense data, which I remembered, are known to have existed in the past. This knowledge supplies our data. But if we are to be able to draw inferences from these data, if we are to know of the existence of matter of other people, of the past before our individual memory begins, or of the future, we must know general principles of some kind by means of which inferences can be drawn. It must be known to us that the existence of some one sort of thing A is a sign of the existence of some other sort of thing B. Either at the same time as A, or at some earlier or later time, as for example, thunder is a sign of the earlier existence of lightning. If this were not known to us, we could never extend our knowledge beyond the sphere of our private experience. And this sphere, as we have seen, is exceedingly limited. The question we have now to consider is whether such an extension is possible, and if so, how it is affected. Let us take as an illustration a matter about which none of us, in fact, feel the slightest doubt. We are all convinced that the sun will rise tomorrow. Why? Is this belief a mere blind outcome of past experience, or can it be justified as a reasonable belief? It is not easy to find a test by which to judge whether a belief of this kind is reasonable or not, but we can at least ascertain what sort of general beliefs would suffice, if true, to justify the judgment that the sun will rise tomorrow, and the many other similar judgments upon which our actions are based. It is obvious that if we are asked why we believe that the sun will rise tomorrow, we shall naturally answer because it always has risen every day. We have a firm belief that will rise in the future because it has risen in the past. If we are challenged as to why we believe that it will continue to rise as here to fore, we may appeal to the laws of motion. The earth, we shall say, is a freely rotating body, and such bodies do not cease to rotate unless something interferes from outside. And there is nothing outside to interfere with the earth between now and tomorrow. Of course it might be doubted whether we are quite certain that there is nothing outside to interfere, but this is not the interesting doubt. The interesting doubt is as to whether the laws of motion will remain in operation until tomorrow. If this doubt is raised, we find ourselves in the same position as when the doubt about the sun rise was first raised. The only reason for believing the laws of motion will remain in operation is that they have operated hitherto, so far as our knowledge of the past enables us to judge. It is true that we have a greater body of evidence from the past in favor of the laws of motion than we have in favor of the sun rise, because the sunrise is merely a particular case of fulfillment of the laws of motion, and there are countless other particular cases. But the real question is, do any number of cases of a law being fulfilled in the past afford evidence that it will be fulfilled in the future? If not, it becomes plain that we have no ground whatever for expecting the sun to rise tomorrow, or for expecting the bread we shall eat at our next meal not to poison us, or for any of the other scarcely conscious expectations that control our daily lives. It is to be observed that all such expectations are only probable. Thus, we have not to seek for a proof that they must be fulfilled, but only for some reason in favor of the view that they are likely to be fulfilled. Now, in dealing with this question we must, to begin with, make an important distinction without which we should soon become involved in hopeless confusions. Experience has shown us that hitherto, the frequent repetition of some uniform succession or coexistence has been a cause of our expecting the same succession or coexistence on the next occasion. Food that has a certain appearance generally has a certain taste and it is a severe shock to our expectations when the familiar appearance is found to be associated with an unusual taste. Things which we see become associated by habit with certain tactile sensations which we expect if we touch them. One of the horrors of a ghost in many ghost stories is that it fails to give us any sensations of touch. Uneducated people who go abroad for the first time are so surprised as to be incredulous when they find their native language is not understood and this kind of association is not confined to men. In animals also it is very strong. A horse which has been often driven along a certain road resists the attempt to drive him in a different direction. Domestic animals expect food when they see the person who usually feeds them. We know that all these rather crude expectations of uniformity are liable to be misleading. The man who has fed the chicken every day throughout its life at last rings its neck instead showing that more refined views as to the uniformity of nature would have been useful to the chicken. But in spite of the misleadingness of such expectations they nevertheless exist. The mere fact that something has happened a certain number of times causes animals and men to expect that it will happen again. Thus our instincts certainly cause us to believe that the sun will rise tomorrow but we may be in no better opposition than the chicken which unexpectedly has its neck rung. We have therefore to distinguish the fact that past uniformities cause expectations as to the future. From the question whether there is any reasonable ground for giving weight to such expectations after the question of the validity has been raised. The problem we have to discuss is whether there is any reason for believing in what is called the uniformity of nature. The belief in the uniformity of nature is the belief that everything that has happened or will happen is an instance of some general law to which there are no exceptions. The crude expectations which we have been considering are all subject to exceptions and therefore liable to disappoint those who entertain them. But science habitually assumes at least as a working hypothesis that general rules which have exceptions can be replaced by general rules which have no exceptions. Unsupported bodies in air fall is a general rule to which balloons and aeroplanes are exceptions. But the laws of motion and the law of gravitation which account for the fact that most bodies fall also account for the fact that balloons and aeroplanes can rise. Thus the laws of motion and the law of gravitation are not subject to these exceptions. The belief that the sun will rise tomorrow might be falsified if the earth came suddenly into contact with a large body which destroyed its rotation. But the laws of motion and the law of gravitation would not be infringed by such an event. The business of science is to find uniformities such as the laws of motion and the law of gravitation to which so far as our experience extends there are no exceptions. In this search science has been remarkably successful and it may be conceded that such uniformities have held hitherto. This brings us back to the question have we any reason assuming that they have always held in the past to suppose that they will hold in the future. It has been argued that we have reason to know that the future will resemble the past because what was the future has constantly become the past and has always been found to resemble the past so that we really have experience of the future namely of the times which were formerly future which we may call past futures. But such an argument really begs the very question at issue. We have experience of past futures but not of future futures and the question is will future futures resemble past futures? This question is not to be answered by an argument which starts from past futures alone. We have therefore still to see for some principle which shall enable us to know that the future will follow the same laws as the past. The reference to the future in this question is not essential. The same question arises when we apply the laws that work in our experience to past things in which we have no experience as for example in geology or in theories as to the origin of the solar system. The question we really have to ask is when two things have been found to be often associated and no instance is known of the one occurring without the other does the occurrence of one of the two in a fresh instance give any good ground for expecting the other? On our answer to this question must depend the validity of the whole of our expectations as to the future the whole of the results obtained by induction and in fact practically all the beliefs upon which our daily life is based. It must be conceded to begin with that the fact that two things have been found often together and never apart does not by itself suffice to prove demonstratively that they will be found together in the next case we examine. The most we can hope is that the oftener things are found together the more probable it becomes that they will be found together another time and that if they have been found together often enough the probability will amount almost to certainty. It can never quite reach certainty because we know that in spite of frequent repetitions there sometimes is a failure at the last as in the case of the chicken whose neck is wrong. Thus probability is all we ought to seek. It might be urged as against the view we are advocating that we know all natural phenomena to be subject to the reign of law and that sometimes on the basis of observation we can see that only one law can possibly fit the facts of the case. Now to this view there are two answers. The first is that even if some law which has no exceptions applies to our case we can never in practice be sure that we have discovered that law and not one to which there are exceptions. The second is that the reign of law would seem to be itself only probable and that our belief that it will hold in the future or in unexamined cases in the past is itself based upon the very principle we are examining. The principle we are examining may be called the principle of induction and its two parts may be stated as follows. A. When a thing of a certain sort A has been found to be associated with a thing of a certain other sort B and has never been found dissociated from a thing of the sort B the greater the number of cases in which A and B have been associated the greater is the probability that they will be associated in a fresh case in which one of them is known to be present. B. Under the same circumstances a sufficient number of cases of association will make the probability of a fresh association nearly a certainty and will make it approach certainty without limit. As just stated the principle applies only to the verification of our expectation in a single fresh instance but we want also to know that there is a probability in favor of the general law that things of the sort A are always associated with things of the sort B provided a sufficient number of cases of association are known and no cases of failure of association are known. The probability of the general law is obviously less than the probability of the particular case since if the general law is true the particular case must also be true whereas the particular case may be true without the general law being true. Nevertheless the probability of the general law is increased by repetitions just as the probability of the particular cases. We may therefore repeat the two parts of our principle as regards to the general law thus. A. The greater the number of cases in which a thing of the sort A has been found associated with a thing of the sort B the more probable it is if no cases of failure of association are known that A is always associated with B. B. Under the same circumstances a sufficient number of cases of the association of A with B will make it nearly certain that A is always associated with B and will make this general law approach certainty without limit. It should be noted that probability is always relative to certain data. In our case the data are merely the known cases of coexistence of A and B. There may be other data which might be taken into account which would gravely alter the probability. For example a man who had seen a great many white swans might argue by our principle that on the data it was probable that all swans were white and this might be a perfectly sound argument. The argument is not disproved by the fact that some swans are black because a thing may very well happen in spite of the fact that some data render it improbable. In the case of the swans a man might know the color is a very variable characteristic in many species of animals and that therefore an induction as to color is peculiarly liable to error but this knowledge would be a fresh datum by no means proving that the probability relatively to our previous data had been wrongly estimated. The fact therefore that things often fail to fulfill our expectations is no evidence that our expectations will not probably be fulfilled in a given case or a given class of cases thus our inductive principle is at any rate not capable of being disproved by an appeal to experience. The inductive principle however is equally incapable of being proved by an appeal to experience. Experience might conceivably confirm the inductive principle as regards the cases that have been already examined but as regards unexamined cases it is the inductive principle alone that can justify any inference from what has been examined to what has not been examined. All arguments which on the basis of experience argue as to the future or the unexperienced parts of the past or present assume the inductive principle hence we can never use experience to prove the inductive principle without begging the question. Thus we must either accept the inductive principle on the ground of its intrinsic evidence or forego all justification of our expectations about the future. If the principle is unsound we have no reason to expect the sun to rise tomorrow to expect bread to be more nourishing than a stone or to expect that if we throw ourselves off the roof we shall fall. When we see what looks like our best friend approaching us we shall have no reason to suppose that his body is not inhabited by the mind of our worst enemy or of some total stranger. All our conduct is based upon associations which have worked in the past and which we therefore regard as likely to work in the future and this likelihood is dependent for its validity upon the inductive principle. The general principles of science such as the belief in the reign of law and the belief that every event must have a cause are as completely dependent upon the inductive principle as are the beliefs of daily life. All such general principles are believed because mankind have found innumerable instances of their truth and no instances of their falsehood. But this affords no evidence for their truth in the future unless the inductive principle is assumed. Thus, all knowledge which on a basis of experience tells us something about what is not experienced is based upon a belief which experience can neither confirm nor confute yet which at least in its more concrete applications appears to be as firmly rooted in us as many of the facts of experience. The existence and justification of such beliefs for the inductive principle as we shall see is not the only example raises some of the most difficult and most debated problems of philosophy. We will in the next chapter consider briefly what may be said to account for such knowledge and what is its scope and its degree of certainty. End of chapter 6 Chapter 7 of The Problems of Philosophy This is a LibriVox recording. All LibriVox recordings are in the public domain. For more information or to volunteer go to LibriVox.org The Problems of Philosophy by Bertrand Russell Chapter 7 On Our Knowledge of General Principles We saw in the preceding chapter that the principle of induction while necessary to the validity of all arguments based on experience is itself not capable of being proved by experience and yet is unhesitatingly believed by everyone at least in all its concrete applications. In these characteristics the principle of induction does not stand alone. There are a number of other principles which cannot be proved or disproved by experience but are used in arguments which start from what is experienced. Some of these principles have even greater evidence than the principle of induction and the knowledge of them has the same degree of certainty as the knowledge of the existence of sense data. They constitute the means of drawing inferences from what is given in sensation and if what we infer is to be true it is just as necessary that our principles of inference should be true as it is that our data should be true. The principles of inference are apt to be overlooked because of their very obviousness. The assumption involved is assented to without our realizing that it is an assumption but it is very important to realize the use of principles in inference if a correct theory of knowledge is to be obtained for our knowledge of them raises interesting and difficult questions. In all our knowledge of general principles what actually happens is that first of all we realize some particular application of the principle and then we realize that the particularity is irrelevant and that there is a generality which may equally truly be affirmed. This is of course familiar in such matters as teaching arithmetic. Two and two or four is first learned in the case of some particular pair of couples and then in some other particular case and so on until at last it becomes possible to see that it is true of any pair of couples. The same thing happens with logical principles. Supposed to men are discussing what day of the month it is. One of them says at least you will admit that if yesterday was the 15th today must be the 16th. Yes says the other I admit that. And you know the first continues that yesterday was the 15th because you dined with Jones and your diary will tell you that was on the 15th. Yes says the second therefore today is the 16th. Now such an argument is not hard to follow and if it is granted that its premises are true in fact no one will deny that the conclusion must also be true. But it depends for its truth upon an instance of a general logical principle. The logical principle is as follows. Suppose it known that if this is true then that is true. When it is the case that if this is true that is true we shall say that this implies that and that that follows from this. Thus our principle states that if this implies that and this is true then that is true. In other words anything implied by a true proposition is true or whatever follows from a true proposition is true. This principle is really involved at least concrete instances of it are involved in all demonstrations. Whenever one thing which we believe is used to prove something else which we consequently believe this principle is relevant. If anyone asks why should I accept the results of valid arguments based on true premises we can only answer by appealing to our principle. In fact the truth of the principle is impossible to doubt and its obviousness is so great that at first sight it seems almost trivial. Such principles however are not trivial to the philosopher for they show that we may have indubitable knowledge which is in no way derived from objects of sense. The above principle is merely one of a certain number of self-evident logical principles. Some at least of these principles must be granted before any argument of proof becomes possible. When some of them have been granted others can be proved though these others so long as they are simple are just as obvious as the principles taking for granted. For no very good reason three of these principles have been singled out by tradition under the name of laws of thought. They are as follows. One, the law of identity. Whatever is is. Two, the law of contradiction. Nothing can both be and not be. Three, the law of excluded middle. Everything must either be or not be. These three laws are samples of self-evident logical principles but are not really more fundamental or more self-evident than various other similar principles. For instance, the one we consider just now which states that what follows from a true premise is true. The name laws of thought is also misleading for what is important is not the fact that we think in accordance with these laws but the fact that things behave in accordance with them. In other words, the fact that when we think in accordance with them we think truly. But this is a large question to which we must return at a later stage. In addition to the logical principles which enable us to prove from a given premise that something is certainly true, there are other logical principles which enable us to prove from a given premise that there is a greater or less probability that something is true. An example of such principles, perhaps the most important example is the inductive principle which we considered in the preceding chapter. One of the great historic controversies in philosophy is the controversy between the two schools called respectively empiricists and rationalists. The empiricists who are best represented by the British philosophers Locke, Berkeley and Hume maintained that all our knowledge is derived from experience. The rationalists who are represented by the continental philosophers of the 17th century especially Descartes and Leithnitz maintained that in addition to what we know by experience there are certain innate ideas and innate principles which we know independently of experience. It has now become possible to decide with some confidence as to the truth or falsehood of these opposing schools. It must be admitted for the reasons already stated that logical principles are known to us and cannot be themselves proved by experience since all proof presupposes them. In this therefore which was the most important point of the controversy the rationalists were in the right. On the other hand even that part of our knowledge which is logically independent of experience in the sense that experience cannot prove it is yet elicited and caused by experience. It is on occasion of particular experiences that we become aware of the general laws which their connections exemplify. It would certainly be absurd to suppose that there are innate principles in the sense that babies are born with the knowledge of everything which men know and which cannot be deduced from what is experienced. For this reason the word innate would not now be employed to describe our knowledge of logical principles. The phrase a priori is less objectionable and is more usual in modern writers. Thus while admitting that all knowledge is elicited and caused by experience we shall nevertheless hold that some knowledge is a priori in the sense that the experience which makes us think of it does not suffice to prove it but merely so directs our attention that we see its truth without requiring any proof from experience. There is another point of great importance in which the empiricists were in the right as against the rationalists. Nothing can be known to exist except by the help of experience. That is to say if we wish to prove that something of which we have no direct experience exists we must have among our premises the existence of one or more things of which we have direct experience. Our belief that the emperor of China exists for example rest upon testimony and testimony consists in the last analysis of sense data seen or heard in reading or being spoken to. Rationalists believe that from general consideration as to what must be they could deduce the existence of this or that in the actual world. In this belief they seem to have been mistaken. All the knowledge that we can acquire a priori concerning existence seems to be hypothetical. It tells us that if one thing exists another must exist or more generally that if one proposition is true another must be true. This is exemplified by the principles we have already dealt with such as if this is true and this implies that then that is true or if this and that have been repeatedly found connected they will probably be connected in the next instance in which one of them is found. Thus the scope and power of a priori principles is strictly limited. All knowledge that something exists alone. When anything is proved to exist without being known immediately both experience and a priori principles must be required in the proof. Knowledge is called empirical when it rests wholly or partly upon experience. Thus all knowledge which asserts existence is empirical and the only a priori knowledge concerning existence is hypothetical giving connections among things that exist or may exist but not giving actual existence. A priori knowledge is not all of the logical kind we have been hitherto considering. Perhaps the most important example of non-logical a priori knowledge is knowledge as to ethical value. I am not speaking of judgments as to what is useful or as to what is virtuous for such judgments do require empirical premises. I am speaking of judgments as to the intrinsic desirability of things. If something is useful it must be useful because it secures some hint. The end must if we have gone far enough be valuable on its own account and not merely because it is useful for some further end. Thus all judgments as to what is useful depend upon judgments as to what has value on its own account. We judge for example that happiness is more desirable than misery, knowledge, than ignorance, goodwill, than hatred, and so on. Such judgments must in part at least be immediate and a priori. Like our previous a priori judgments they may be elicited by experience and indeed they must be for it seems not possible to judge whether anything is intrinsically valuable unless we have experienced something of the same kind. But it is fairly obvious that they cannot be proved by experience for the fact that a thing exists or does not exist cannot prove either that it is good that it should exist or that it is bad. The pursuit of this subject belongs to ethics where the impossibility of deducing what ought to be from what is has to be established. In the present connection it is only important to realize that knowledge as to what is intrinsically of value is a priori in the same sense in which logic is a priori namely in the sense that the truth of such knowledge can be neither proved nor disproved by experience. All pure mathematics is a priori like logic. This was strenuously denied by the empirical philosophers who maintained that experience was as much the source of our knowledge of arithmetic as of our knowledge of geography. They maintained that by the repeated experience of seeing two things and two other things and finding that all together they made four things we were led by induction to the conclusion that two things and two other things would always make four things all together. If however this were the source of our knowledge that two and two are four we should proceed differently in persuading ourselves of its truth from the way in which we do actually proceed. In fact a certain number of instances are needed to make us think of too abstractly rather than of two coins or two books or two people or two of any other specified kind. But as soon as we are able to divest our thoughts of irrelevant particularity we become able to see the general principle that two and two are four. Any one instance is seen to be typical and the examination of other instances becomes unnecessary. The same thing is exemplified in geometry. If we want to prove some property of all triangles we draw some one triangle and reason about it but we can avoid making use of any property which it does not share with all other triangles and thus from our particular case we obtain a general result. We do not in fact feel our certainty that two and two are four increased by fresh instances because as soon as we have seen the truth of this proposition our certainty becomes so great as to be incapable of growing greater. Moreover we feel some quality of necessity about the proposition two and two are four which is absent from even the best attested empirical generalizations. Such generalizations always remain mere facts. We feel that there might be a world in which they were false though in the actual world they happen to be true. In any possible world on the contrary we feel that two and two would be four. This is not a mere fact but a necessity to which everything actual and possible must conform. The case may be made clearer by considering a genuinely empirical generalization such as all men are mortal. It is plain that we believe this proposition in the first place because there is no known instance of men living beyond a certain age and in the second place because there seem to be physiological grounds for thinking that an organism such as a man's body must soon or later wear out. Neglecting the second ground and considering merely our experience of men's mortality it is plain that we should not be content with one quite clearly understood instance of a man dying. Whereas in the case of two and two or four one instance does suffice when carefully considered to persuade us that the same must happen in any other instance. Also we can be forced to admit on reflection that there may be some doubt however slight as to whether all men are mortal. This may be made plain by the attempt to imagine two different worlds in one of which there are men who are not mortal while in the other two and two make five. When Swift invites us to consider the race of strode bugs who never die we are able to acquiesce an imagination but a world where two and two make five seems quite on a different level we feel that such a world if there were one would upset the whole fabric of our knowledge and reduce us to utter doubt. The fact is that in simple mathematical judgments such as two and two or four and also in many judgments of logic we can know the general proposition without inferring it from instances although some instances usually necessary to make clear to us what the general proposition means. This is why there is real utility in the process of deduction which goes from the general to the general or from the general to the particular as well as in the process of induction which goes from the particular to the particular or from the particular to the general. It is an old debate among philosophers whether deduction ever gives new knowledge. We can now see that in certain cases at least it does do so. If we already know that two and two always make four and we know that brown and Jones are two and so are Robinson and Smith we can deduce that brown and Jones and Robinson and Smith are four. This is new knowledge not contained in our premises because the general proposition two and two or four never told us there were such people as brown and Jones and Robinson and Smith and the particular premises do not tell us that there were four of them whereas the particular proposition deduced does tell us both these things. But the newness of knowledge is much less certain if we take the stock instance of deduction that is always given in books on logic namely all men are mortal Socrates is a man therefore Socrates is mortal. In this case what we really know beyond reasonable doubt is that certain men ABC were mortal since in fact they have died. If Socrates is one of these men it is foolish to go the round about way through all men are mortal to arrive at the conclusion that probably Socrates is mortal. If Socrates is not one of the men on whom our induction is based we shall still do better to argue straight from our ABC to Socrates than to go around by the general proposition all men are mortal. For the probability that Socrates is mortal is greater on our data than the probability that all men are mortal. This is obvious because if all men are mortal so is Socrates but if Socrates is mortal it does not follow that all men are mortal. Hence we shall reach the conclusion that Socrates is mortal with a greater approach to certainty if we make our argument purely inductive then if we go by way of all men are mortal and then use deduction. This illustrates the difference between general propositions known a priori such as two and two are four and empirical generalizations such as all men are mortal. In regard to the former deduction is the right mode of argument whereas in regard to the latter induction is always theoretically preferable and warrants a greater confidence in the truth of our conclusion because all empirical generalizations are more uncertain than the instances of them. We have now seen that there are propositions known a priori and that among them are the propositions of logic and pure mathematics as well as the fundamental propositions of ethics the question which must next occupy us is this how is it possible that there should be such knowledge and more particularly how can there be knowledge of general propositions in cases where we have not examined all the instances and indeed never can examine them all because their number is infinite these questions which were first brought prominently forward by the German philosopher Kant 1724 to 1804 are very difficult and historically very important. End of chapter 7 Chapter 8 of The Problems of Philosophy This is a LibriVox recording. All LibriVox recordings are in the public domain. For more information or to volunteer please visit LibriVox.org Recording by ML Cohen www.mojomu411.com Cleveland, Ohio August 2007 The Problems of Philosophy by Bertrand Russell Chapter 8 How a Priory Knowledge is Possible Immanuel Kant is generally regarded as the greatest of the modern philosophers Though he lived through the Seven Years War and the French Revolution he never interrupted his teaching of philosophy at Königsberg in East Prussia. His most distinctive contribution was the invention of what he called the critical philosophy which assuming as a datum that there is knowledge of various kinds inquired how such knowledge comes to be possible and deduced from the answer to this inquiry many metaphysical results as to the nature of the world. Whether these results were valid may well be doubted but Kant undubitably deserves credit for two things. First for having perceived that we have a Priory Knowledge which is not purely analytic that is such that the opposite would be self-contradictory and secondly for having made evident the philosophical importance of the theory of knowledge. Before the time of Kant it was generally held that whatever knowledge was a Priory must be analytic but this word means will be best illustrated by examples. If I say a bald man is a man a plain figure is a figure a bad poet is a poet I make a purely analytical judgment the subject spoken about is given as having at least two properties of which one is singled out to be asserted of it. Such propositions as the above are trivial and would never be enunciated in real life except by an order preparing the way for a piece of sophistry. They are called analytic because the predicate is obtained by merely analyzing the subject. Before the time of Kant it was thought that all judgments of which we could be certain a Priory were of this kind that in all of them there was a predicate which was only part of the subject of which it was asserted. If this were so we should be involved in a definite contradiction if we attempted to deny anything that could be known a Priory. A bald man is not bald would assert and deny baldness of the same man and would therefore contradict itself. Thus according to the philosophers before Kant the law of contradiction which asserts that nothing can at the same time have and not have a certain property suffice to establish the truth of all a Priory knowledge. Hume 1711 to 1776 who preceded Kant accepting the usual view as to what make knowledge a Priory discovered that in many cases which had previously been supposed analytic and notably in the case of cause and effect the connection was really synthetic. Before Hume rationales at least had supposed that the effect could be logically deduced from the cause if only we have sufficient knowledge. Hume argued correctly as we now be generally admitted that this could not be done hence he inferred the far more doubtful proposition that nothing could be known a Priory about the connection of cause and effect. Kant who had been educated in a rationalist tradition was much perturbed by Hume's skepticism and endeavored to find an answer to it. He perceived that not only the connection of cause and effect but all the propositions of arithmetic and geometry are synthetic that is not analytic and all these propositions no analysis of the subject will reveal the predicate. His stock instance was the proposition 7 plus 5 equals 12. He pointed out quite truly that 7 and 5 have to be put together to give 12. The idea of 12 was not contained in them nor even in the idea of adding them together. Thus he would lead to the conclusion that all pure mathematics though a Priory is synthetic and this conclusion raised a new problem of which he endeavored to find the solution. The question which Kant put at the beginning of his philosophy namely how is pure mathematics possible is an interesting and difficult one to which every philosophy which is not purely skeptical must find some answer. The answer of the pure empiricist that our mathematical knowledge is derived by induction from particular instances we have already seen to be inadequate for two reasons. First, that the validity of the inductive principle itself cannot be proved by induction. Secondly, that the general propositions of mathematics such as 2 and 2 always makes 4 can obviously be known with certainty by consideration of a single instance and gain nothing by enumeration of other cases in which they have been found to be true. Thus our knowledge of the general propositions of mathematics and the same applies to logic must be accounted for otherwise than our merely probable knowledge of empirical generalization such as all men are mortal. The problem arises through the fact that such knowledge is general whereas all experience is particular. It seems strange that we should apparently be able to know some truths in advance about particular things of which we have as yet no experience. But it cannot easily be doubted that logic and arithmetic will apply to such things. We do not know who will be the inhabitants of London a hundred years hence but we know that any two of them and any other two of them will make four of them. This apparent power of anticipating facts about things of which we have no experience is certainly surprising. Consolution of the problem though not valid in my opinion is interesting. It is however very difficult and is differently understood by different philosophers. We can therefore only give the nearest outline of it and even that will be thought misleading by many exponents of cons system. What Kant maintained was that in all our experience there are two elements to be distinguished the one due to the object that is to what we have called the physical object the other due to our own nature. We saw in discussing matter and sense data that the physical object is different from the associated sense data and that the sense data are to be regarded as resulting from an interaction between the physical object and ourselves. So far we are in agreement with Kant. But what is distinctive of Kant is the way in which he apportions the shares of ourselves and the physical objects respectively. He considers that the crude material given in sensation the color, hardness, etc is due to the object and that what we supply is the arrangement in space and time and all the relations between sense data which result from comparison or from considering one as the cause of the other or in any other way. His chief reason in favor of this view is that we seem to have a priori knowledge as to space and time and causality and comparison but not as to the actual crude material of sensation. We can be sure, he says, that anything we shall ever experience must show the characteristics affirmed of it in our a priori knowledge because these characteristics are due to our own nature and therefore nothing can ever come into our experience without acquiring these characteristics. The physical object which he calls the quote thing in itself and quote he regards as essentially unknowable. What can be known is the object as we have it in experience which he calls quote phenomenon. Kant's thing in itself is identical in definition with the physical object namely, it is the cause of sensations. In the properties deduced from the definition it is not identical since Kant held in spite of some inconsistencies regards cause that we can know that none of the categories are applicable to the quote thing in itself. The phenomenon being a joint product of us and the thing in itself is sure to have those characteristics which are due to us and is therefore sure to conform to our a priori knowledge. Hence this knowledge though true of all actual impossible experience must not be supposed to apply outside experience. Thus in spite of the existence of a priori knowledge we cannot know anything about the thing in itself or about what is not an actual or possible object of experience. In this way he tried to reconcile and harmonize the contentions of the rationalists with the arguments of the empiricists. Apart from the minor grounds on which Kant's philosophy may be criticized there is one main objection which seems fatal to any attempt to deal with the problem of a priori knowledge by his method. The thing to be accounted for is our certainty that the facts must always conform to logic and arithmetic. To say that logic and arithmetic are contributed by us does not account for this. How our nature is as much a fact of the existing world as anything and there can be no certainty that it will remain constant. It might happen if Kant is right that tomorrow our nature would so change as to make two and two become five. This possibility seems never to have occurred to him yet it is one which utterly destroys the certainty and universality which he is anxious to vindicate for arithmetical propositions. It is true that this possibility formally is inconsistent with the Kantian view that time itself is a form imposed by the subject upon phenomena so that our real self is not in time and has no tomorrow. But he will still have to suppose that the time order of phenomena is determined by characteristics of what is behind phenomena and this suffices for the substance of our argument. Reflection moreover seems to make it clear that if there is any truth in our arithmetical beliefs they must apply to things equally whether we think of them or not. Two physical objects and two other physical objects must make four physical objects even if physical objects cannot be experienced. To assert this is certainly within the scope of what we mean when we state that two and two are four. Its truth is just as indubitable as the truth of the assertion that two phenomena and two other phenomena make four phenomena. Thus, constitution unduly limits the scope of a priori propositions in addition to failing in the attempt at explaining their certainty. Apart from the special doctrines advocates by Kant it is very common among philosophers to regard what is a priori as in some sense mental as concerned rather with the way we must think than with any fact of the outer world. We noted in the preceding chapter the three principles commonly called quote laws of thought end quote. The view which led to their being so named is a natural one but there are strong reasons for thinking that is erroneous. Let us take as an illustration the law of contradiction. This is commonly stated in the form quote nothing can both be and not be end quote which is intended to express the fact that nothing can at once have and not have a given quality. Thus for example if a tree is a beach it cannot also be not a beach if my table is rectangular it cannot also be not rectangular and so on. Now what makes it natural to call this principle a law of thought is that it is by thought rather than by outward observation that we persuade ourselves of its necessary truth. When we have seen that a tree is a beach we do not need to look again in order to ascertain whether there is also not a beach thought alone makes us know that this is impossible but the conclusion that the law of contradiction is a law of thought is nevertheless erroneous. What we believe when we believe the law of contradiction is not that the mind is so made that it must believe the law of contradiction. This belief is a subsequent result of psychological reflection which presupposes the belief in the law of contradiction. The belief in the law of contradiction is a belief about things not only about thoughts it is not for example the belief that if we think a certain tree is a beach we cannot at the same time think that it is not a beach. It is the belief that if the tree is a beach it cannot at the same time be not a beach. Thus the law of contradiction is about things and not merely about thoughts and although belief in the law of contradiction is a thought the law of contradiction itself is not a thought but a fact concerning the things in the world. If this which we believe when we believe the law of contradiction we're not true of all the things in the world. The fact that we were compelled to think it's true would not save the law of contradiction from being false and this shows that the law is not a law of thought. A similar judgment applies to any other a priori judgment. When we judge that two and two are four, we are not making a judgment about our thoughts, but about all actual or possible couples. The fact that our minds are so constituted as to believe that two and two are four, though it is true, is emphatically not what we assert when we assert that two and two are four. And no fact about the constitution of our minds could make it true that two and two are four. Thus, our a priori knowledge, if it is not erroneous, is not merely knowledge about the constitution of our minds, but is applicable to whatever the world may contain, both what is mental and what is not mental. The fact seems to be that all our a priori knowledge is concerned with entities which do not, properly speaking, exist, either in the mental or in the physical world. These entities are such as can be named by parts of speech which are not substantive. They are such entities as qualities and relations. Suppose, for instance, that I am in my room. I exist, and my room exists. But does in exist? Yet obviously the word in has a meaning. It denotes a relation which holds between me and my room. This relation is something, although we cannot say that it exists in the same sense in which I and my room exist. The relation in is something which we can think about and understand, for if we could not understand it, we could not understand a sentence, I am in my room. Many philosophers following Kant have maintained that relations are the work of the mind, that things in themselves have no relations, but that the mind brings them together in one act of thought and thus produces the relations which it judges them to have. This view, however, seems open to objections similar to those which we urged before against Kant. It seems plain that it is not thought which produces the truth of the proposition, quote, I am in my room. It may be true that an earwig is my room, even if neither I nor the earwig nor anyone else is aware of this truth, for this truth concerns only the earwig and the room. Thus relations, as we shall see more fully in the next chapter, must be placed in a world which is neither mental nor physical. This world is of great importance to philosophy and particularly to the problems of a priori knowledge. In the next chapter, we shall proceed to develop its nature and its bearing upon the questions with which we have been dealing. CHAPTER IX. At the end of the preceding chapter, we saw that such entities as relations appear to have a being which is in some way different from that of physical objects and also different from that of minds and from that of sense data. In the present chapter, we have to consider what is the nature of this kind of being and also what objects there are that have this kind of being. We will begin with the latter question. The problem with which we are now concerned is a very old one since it was brought into philosophy by Plato. Plato's theory of ideas is an attempt to solve this very problem and in my opinion, it is one of the most successful attempts hitherto made. The theory to be advocated and what follows is largely Plato's with merely such modifications as time is shown to be necessary. The way the problem arose for Plato was more or less as follows. Let us consider, say, such a notion as justice. If we ask ourselves what justice is, it is natural to proceed by considering this, that, and the other just act, with a view to discovering what they have in common. They must all, in some sense, partake of a common nature, which will be found in whatever is just and in nothing else. This common nature, in virtue of which they are all just, will be justice itself, the pure essence, the admixture of which, with facts of ordinary life, produces the multiplicity of just acts. Similarly, with any other word which may be applicable to common facts, such as whiteness, for example. The word will be applicable to a number of particular things because they all participate in a common nature or essence. This pure essence is what Plato calls an idea or form. It must not be supposed that ideas, in his sense, exist in minds, though they may be apprehended by minds. The idea justice is not identical with anything that is just. It is something other than particular things, which particular things partake of. Not being particular, it cannot itself exist in the world of sense. Moreover, it is not fleeting or changeable like the things of sense. It is eternally itself, immutable and indestructible. Thus, Plato has led to a super-sensible world, more real than the common world of sense. The unchangeable world of ideas, which alone gives to the world of sense whatever pale reflection of reality may belong to it. The truly real world, for Plato, is the world of ideas. For, whatever we may attempt to say about things in the world of sense, we can only succeed in saying that they participate in such and such ideas, which, therefore, constitute all their character. Hence, it is easy to pass on into amisticism. We may hope, in a mystical illumination, to see the ideas as we see objects of sense, and we may imagine that the ideas exist in heaven. These mystical developments are very natural, but the basis of the theory is in logic, and it is as based in logic that we have to consider it. The word idea has acquired, in the course of time, many associations which are quite misleading when applied to Plato's ideas. We shall therefore use the word universal instead of the word idea to describe what Plato meant. The essence of the sort of entity that Plato meant is that it is opposed to the particular things that are given in sensation. We speak of whatever is given in sensation or is of the same nature as things given in sensation as a particular. By opposition to this, a universal will be anything which may be shared by many particulars and has those characteristics which, as we saw, distinguish justice and whiteness from just acts and white things. When we examine common words, we find that, broadly speaking, proper names stand for particulars, while other substantives, adjectives, prepositions and verbs stand for universals. Pronouns stand for particulars, but are ambiguous. It is only by the context or the circumstances that we know what particulars they stand for. The word now stands for a particular, namely, the present moment. But like pronouns, it stands for an ambiguous particular because the present is always changing. It will be seen that no sentence can be made up without at least one word which denotes a universal. The nearest approach would be some such statement as I like this, but even here the word like denotes a universal for I may like other things and other people may like things. Thus, all truths involve universals and all knowledge of truths involves acquaintance with universals. Seeing that nearly all the words to be found in the dictionary stand for universals, it is strange that hardly anybody except students of philosophy ever realizes that there are such entities as universals. We do not naturally dwell upon these words in a sentence which do not stand for particulars. And if we are forced to dwell upon a word which stands for a universal, we naturally think of it as standing for some one of the particulars that come under the universal. When, for example, we hear the sentence, Charles the First's head was cut off, we may naturally enough think of Charles the First, of Charles the First's head, and of the operation of cutting off his head, which are all particulars, but we do not naturally dwell upon what is meant by the word head or the word cut, which is a universal. We feel such words to be incomplete and insubstantial. They seem to demand a context before anything can be done with them. Hence, we succeed in avoiding all notice of universals as such until the study of philosophy forces them upon our attention. Even among philosophers, we may say, broadly, that only those universals which are named by adjectives or substandives have been much or often recognized, while those named by verbs and prepositions have been usually overlooked. This omission has had a very great effect upon philosophy. It is hardly too much to say that most metaphysics, since Spinoza, has been largely determined by it. The way this has occurred is, in outline, as follows. Speaking generally, adjectives and common nouns express qualities or properties of single things, whereas prepositions and verbs tend to express relations between two or more things. Thus the neglect of prepositions and verbs led to the belief that every preposition can be regarded as attributing a property to a single thing, rather than as expressing a relation between two or more things. Hence it was supposed that, ultimately, there can be no such entities as relations between things. Hence, either there can be only one thing in the universe, or, if there are many things, they cannot possibly interact in any way, since any interaction would be a relation and relations are impossible. The first of these views, advocated by Spinoza, and held in our own day by Bradley and many other philosophers, is called monism. The second, advocated by Liebniz, but not very common nowadays, is called monadism, because each of the isolated things is called a monad. Both these opposing philosophies, interesting as they are, result, in my opinion, from an undue attention to one sort of universals, namely the sort represented by adjectives and substantives, rather than by verbs and preposition. As a matter of fact, if anyone were anxious to deny altogether that there are such things as universals, we should find that we cannot strictly prove that there are such entities as qualities, i.e., the universals represented by adjectives and substantives, whereas we can prove that there must be relations, i.e., the sort of universals generally represented by verbs and prepositions. Let us take, in illustration, the universal whiteness. If we believe that there is such a universal, we shall find that things are white because they have the quality of whiteness. This view, however, was strenuously denied by Berkeley and Hume, who have been followed in this by later empiricists. The form which their denial took was to deny that there are such things as abstract ideas. When we want to think of whiteness, they said, we form an image of some particular white thing and reason concerning this particular, taking care not to deduce anything concerning it which we cannot see to be equally true of any other white thing. As an account of our actual mental processes, this is no doubt largely true. In geometry, for example, when we wish to prove something about all triangles, we draw a particular triangle and reason about it, taking care not to use any characteristic which it does not share with other triangles. The beginner, in order to avoid error, often finds it useful to draw several triangles, as unlike each other as possible in order to make sure that his reasoning is equally applicable to all of them. But a difficulty emerges as soon as we ask ourselves how we know that a thing is white or a triangle. If we wish to avoid the universal's whiteness and triangularity, we shall choose some particular patch of white or some particular triangle and say that anything is white or a triangle if it has the right sort of resemblance to our chosen particular. But then the resemblance required will have to be a universal. Since there are many white things, the resemblance must hold between many pairs of particular white things, and this is the characteristic of a universal. It will be useless to say that there is a different resemblance for each pair. For then we shall have to say that these resemblances resemble each other. And thus, at last we shall be forced to admit resemblance as a universal. The relation of resemblance, therefore, must be a true universal. And having been forced to admit this universal, we find that it is no longer worthwhile to invent difficult and unplausible theories to avoid the emission of such universal's as whiteness and triangularity. Berkeley and Hume failed to perceive this refutation of their rejection of abstract ideas because, like their adversaries, they only thought of qualities and altogether ignored relations as universals. We have therefore here another respect in which the rationalists appear to have been in the right as against the empiricists. Although, owing to the neglect or denial of relations, the deductions made by rationalists were, if anything, more apt to be mistaken than those made by empiricists. Having now seen that there must be such entities as universals, the next point to be proved is that their being is not merely mental. By this is meant that whatever being belongs to them is independent of their being thought of or in any way apprehended by minds. We have already touched on this subject at the end of the preceding chapter, but we must now consider more fully what sort of being it is that belongs to universals. Consider such a proposition as Edinburgh is north of London. Here we have a relation between two places, and it seems plain that the relation subsists independently of our knowledge of it. When we come to know that Edinburgh is north of London, we must know something which has to do only with Edinburgh in London. We do not cause the truth of the proposition by coming to know it. On the contrary, we merely apprehend a fact which was there before we knew it. The part of the earth's surface where Edinburgh stands would be north of the part where London stands, even if there were no human being to know about north and south, and even if there were no minds at all in the universe. This is, of course, denied by many philosophers, either for Berkeley's reasons or for Kant's. But we have already considered these reasons and decided that they are inadequate. We may therefore now assume it to be true that nothing mental is presupposed in the fact that Edinburgh is north of London, but this fact involves the relation north of, which is a universal, and it would be impossible for the whole fact to involve nothing mental if the relation north of, the constituent part of the fact, did involve anything mental. Hence, we must admit that the relation, like the terms it relates, is not dependent upon thought, but belongs to the independent world which thought apprehends, but does not create. This conclusion, however, is met by the difficulty that the relation north of does not seem to exist in the same sense in which Edinburgh and London exist. If we ask, where and when does this relation exist, the answer must be nowhere and no when. There is no place or time where we can find the relation north of. It does not exist in Edinburgh any more than in London, for it relates the two and is neutral as between them. Nor can we say that it exists at any particular time. Now, everything that can be apprehended by the senses or by introspection exists at some particular time. Hence, the relation north of is radically different from such things. It is neither in space nor in time, neither material nor mental, yet it is something. It is largely the very peculiar kind of being that belongs to universals which has led many people to suppose that they are really mental. We can think of a universal and our thinking then exists like any other mental act. Suppose, for example, that we are thinking of whiteness. Then in one sense it may be said that whiteness is in our mind. We have here the same ambiguity as we noted in discussing Berkeley in Chapter 4. In the strict sense it is not whiteness that is in our mind but the act of thinking of whiteness. The connected ambiguity and the word idea which we noted at the same time also causes confusion here. In one sense of this word namely the sense in which it denotes the object of an act of thought whiteness is an idea. Hence, if the ambiguity is not guarded against we may come to think that whiteness is an idea in the other sense i.e. an act of thought and thus we come to think that whiteness is mental. But in so thinking we rob it of its essential quality one man's act of thought is necessarily a different thing from another man's. One man's act of thought at one time is necessarily a different thing from the same man's act of thought at another time. Hence, if whiteness were the thought as opposed to its object no two different men could think of it and no one man could think of it twice. That which many different thoughts of whiteness have in common this object is different from all of them. Thus, universals are not thoughts, though when known they are the objects of thoughts. We shall find it convenient only to speak of things existing when they are in time. That is to say, when we can point to some time at which they exist not excluding the possibility of their existing at all times. Thus thoughts and feelings, minds and physical objects exist but universals do not exist in this sense. We shall say that they subsist or have being where being is opposed to existence as being timeless. The world of universals, therefore may also be described as the world of being. The world of being is unchangeable rigid, exact delightful to the mathematician the logician the builder of metaphysical systems with perfection more than life. The world of existence is fleeting vague, without sharp boundaries without any clear plan or arrangement but it contains all thoughts and feelings all the data of sense and all physical objects everything that can do either good or harm everything that makes any difference to the value of life and the world. According to our temperaments we shall prefer the contemplation of the one or of the other the one we do not prefer will probably seem to us a pale shadow of the one we prefer and hardly worthy to be regarded as in any sense real but the truth is that both have the same claim on our impartial attention both are real and both are important to the metaphysician. Indeed, no sooner have we distinguished the two worlds than it becomes necessary to consider their relations but first of all we must examine our knowledge of universals. This consideration will occupy us in the following chapter where we shall find that it solves the problem of a priori knowledge from which we were first led to consider universals. End of Chapter 9 The Problems of Philosophy This recording is in the public domain Chapter 10 of The Problems of Philosophy This is a LibriVox recording all LibriVox recordings are in the public domain for more information or to find out how to volunteer please contact LibriVox.org The Problems of Philosophy by Bertrand Russell Chapter 10 On Our Knowledge of Universals In regard to one man's knowledge at a given time universals, like particulars may be divided into those known by acquaintance those known only by description and those not known either by acquaintance or by description. Let us consider first the knowledge of universals by acquaintance it is obvious to begin with that we are acquainted with such universals as white, red, black sweet, sour, loud, hard, etc. i.e. with qualities which are exemplified and sense data. When we see a white patch we are acquainted in the first instance with a particular patch but by seeing many white patches we easily learn to abstract the whiteness which they all have in common and in learning to do this we are learning to be acquainted with whiteness a similar process will make us acquainted with any other universal of the same sort. Universals of this sort may be called sensible qualities they can be apprehended with less effort of abstraction than any others and they seem less removed from particulars than other universals are The easiest relations to apprehend are those which hold between the different parts of a single complex sense data for example the whole of the page on which I am writing thus the whole page is included in one sense data but I perceive that some parts of the page are to the left of other parts and some parts are above other parts the process of abstraction in this case seems to proceed somewhat as follows I see successively a number of sense data in which one part is to the left of another I perceive in the case of different white patches that all these sense data have something in common and by abstraction I find that what they have in common is a certain relation between their parts namely the relation which I call being to the left of in this way I become acquainted with the universal relation in like manner I become aware of the relation of before and after in time suppose I hear a chime of bells when the last bell of the chime sounds I can retain the whole chime before my mind and I can perceive that the earlier bells came before the later ones also in memory I perceive that what I am remembering came before the present time from either of these sources I can abstract the universal relation of before and after just as I abstracted the universal relation being to the left of thus time relations like space relations are among those with which we are acquainted another relation with which we become acquainted in much the same way is resemblance if I see simultaneously two shades of green I can see that they resemble each other if I also see a shade of red at the same time I can see that the two shades of green have more resemblances to each other than either has to the red in this way I become acquainted with the universal resemblance or similarity with the universals as between particulars there are relations of which we may be immediately aware we have just seen that we can perceive that the resemblance between two shades of green is greater than the resemblance between a shade of red and a shade of green here we are dealing with a relation namely greater than between two relations our knowledge of such relations though it requires more power of abstraction than is required for perceiving qualities of sense data appears to be equally immediate and at least in some cases equally indubitable thus there is immediate knowledge concerning universals as well as concerning sense data returning now to the problem of a priori knowledge which we left unsolved when we began the consideration of universals we find ourselves in a position to deal with it in a much more satisfactory manner than was possible before let us revert to the proposition two and two are four it is fairly obvious and view of what has been said that this proposition states a relation between the universal two and the universal four this suggests a proposition with which we shall now endeavor to establish namely all a priori knowledge deals exclusively with the relations of universals this proposition is of great importance and goes a long way towards solving our previous difficulties concerning a priori knowledge the only case in which it might seem at first sight as if our proposition were untrue is the case in which an a priori proposition states that all of one class of particulars belong to some other class or what comes to the same thing that all particulars having some one property also have some other in this case it might seem as though we were dealing with the particulars that have the property rather than with the property the proposition two and two are four is really a case in point for this may be stated in the form any two and any other two are four or any collection formed of two twos is a collection of four if we can show that such statements as this really deal only with universals our proposition may be regarded as proved one way of discovering what a proposition deals with is to ask ourselves what words we must understand in other words what objects we must be acquainted with in order to see what the proposition means as soon as we see what the proposition means even if we do not yet know whether it is true or false it is evident that we must have acquaintance with whatever is really dealt with by the proposition by applying this test it appears that many propositions which might seem to be concerned with particulars are concerned only with universals in the special case of two and two or four even when we interpret it as meaning any collection formed of two twos is a collection of four it is plain that we can understand the proposition i.e. we can see what it is that it asserts as soon as we know what is meant by a collection and two and four it is quite unnecessary to know all the couples in the world it is quite necessary obviously we could never understand the proposition since the couples are infinitely numerous and therefore cannot all be known to us thus although our general statement implies statements about particular couples as soon as we know that there are such particular couples yet it does not itself assert or imply that there are such particular couples and thus fails to make any statement whatever about any actual particular couple the statement made is about couple the universal and not about this or that couple thus the statement two and two or four deals exclusively with universals and therefore may be known by anybody who is acquainted with the universals concerned and can perceive the relation between them which the statement asserts it must be taken as a fact discovered by reflecting upon our knowledge that we have the power of sometimes perceiving such relations between universals and therefore of sometimes knowing general a priori propositions such as those of arithmetic and logic the thing that seemed mysterious when we formally considered such knowledge was that it seemed to anticipate and control experience this however we can now see to have been an error no fact concerning anything capable of being experienced can be known independently of experience we know a priori that two things and two other things together make four things but we do not know a priori that if brown and jones are two and robinson and smith are two then brown and jones and robinson and smith are four the reason is that this proposition cannot be understood at all unless we know that there are such people as brown and jones and robinson and smith and this we can only know by experience hence although our general proposition is a priori all its applications to actual particulars involve experience and therefore contain an empirical element in this way what seemed mysterious in our a priori knowledge is seen to have been based upon an error it will serve to make the point clearer if we contrast our genuine a priori judgment with an empirical generalization such as all men are mortals here is before we can understand what the proposition means as soon as we understand the universals involved namely man and mortal it is obviously unnecessary to have an individual acquaintance with the whole human race in order to understand what our proposition means thus the difference between an a priori general proposition and an empirical generalization does not come in the meaning of the proposition it comes in the nature of the evidence for it in the empirical case the evidence consists in the particular instances we believe that all men are mortal because we know that there are innumerable instances of men dying and no instances of their living beyond a certain age we do not believe it because we see a connection between the universal man and the universal mortal it is true that a physiology can prove assuming the general laws that govern living bodies that no living organism can last forever that gives a connection between man and mortality which would enable us to assert our proposition without appealing to the special evidence of men dying but that only means that our generalization has been subsumed under a wider generalization for which the evidence is still of the same kind though more extensive the progress of science is constantly producing such subsumptions and therefore giving a constantly wider inductive basis for scientific generalizations but although this gives a greater degree of certainty it does not give a different kind the ultimate ground remains inductive i.e. derived from instances and not from a priori connection of universals such as we have in a logic and arithmetic two opposite points are to be observed concerning a priori general propositions the first is that if many particular instances are known our general proposition may be arrived at in the first instance by induction and the connection of universals may be only subsequently perceived for example it is known that if we draw perpendicular to the sides of a triangle from the opposite angles all three perpendiculars meet in a point this experience might lead us to look for the general proof and find it such cases are common in the experience of every mathematician the other point is more interesting and of more philosophical importance it is that we may sometimes know a general proposition in cases where we do not know a single instance of it take such a case as the following we know that any two numbers can be multiplied together and will give a third called their product we know that all pairs of integers the product of which is less than a hundred have been actually multiplied together and the value of the product recorded in the multiplication table but we also know that the number of integers is infinite and that only a finite number of the pairs of integers have ever been or ever will be thought of by human beings hence it follows that there are pairs of integers which never have been and never will be thought of by human beings and that all of them deal with integers the product of which is over a hundred hence we arrive at the proposition all products of two integers which never have been and never will be thought of by any human being are over a hundred here is a general proposition of which the truth is undeniable and yet from the very nature of the case we can never give an instance because any two numbers we may think of are excluded by the terms of the proposition this possibility of knowledge of general propositions of which no instance can be given is often denied because it is not perceived that the knowledge of such propositions only requires a knowledge of the relations of universals and does not require any knowledge of instances of the universals in question yet the knowledge of such general propositions is quite vital to a great deal of what is generally admitted to be known for example we saw in our early chapters that knowledge of physical objects and sense data is only obtained by inference and that they are not things with which we are acquainted hence we can never know any proposition of the form this is a physical object where this is something immediately known it follows that all our knowledge concerning physical objects is such that no actual instance can be given we can give instances of the associated sense data but we cannot give instances of such objects hence our knowledge as to physical objects depends throughout upon this possibility of general knowledge where no instance can be given and the same applies to our knowledge of other people's minds or of any other class of things of which no instance is known to us by acquaintance we may now take a survey of the sources of our knowledge as they have appeared in the course of our analysis we have first to distinguish acquaintance and knowledge of truths in each there are two kinds one immediate and one derivative our immediate knowledge of things which we called acquaintance consists of two sorts according as the things are known are particulars or universals among particulars we have acquaintance with sense data and probably with ourselves among universals there must be no principle by which we can decide which can be known by acquaintance but it is clear that among those that can be so known are sensible qualities relations of space and time similarity and certain abstract logical universals our derivative knowledge of things which we call knowledge by description always involves both acquaintance with something and knowledge of truths our immediate knowledge of truths may be called intuitive knowledge and the truths so known may be called self-evident truths among such truths are included those which merely state what is given in sense and also certain abstract logical and arithmetical principles and though with less certainty some ethical propositions our derivative knowledge of truths consists of everything that we can deduce from self-evident truths and self-evident principles of deduction if the above account is correct all our knowledge of truths depends upon our intuitive knowledge it therefore becomes important to consider the nature and scope of intuitive knowledge in much the same way as at an earlier stage we consider the nature and scope of knowledge by acquaintance but knowledge of truths raises a further problem which does not arise in regard to knowledge of things namely the problem of error some of our beliefs turn out to be erroneous and therefore it becomes necessary to consider how if at all we can distinguish knowledge from error this problem does not arise with regard to knowledge by acquaintance for whatever may be the object of acquaintance even in dreams and hallucinations there is no error involved so long as we do not go beyond the immediate object error can only arise when we regard the immediate object i.e. the sense datum as the mark of some physical object thus the problems connected with knowledge of truths are more difficult than those connected with knowledge of things as the first of the problems connected with knowledge of truths let us examine the nature and scope of our intuitive judgments end of chapter 10 on our knowledge of universals this recording is in the public domain chapter 11 of the problems of philosophy this is a LibriVox recording all LibriVox recordings are in the public domain for more information or to volunteer please visit LibriVox.org the problems of philosophy by Bertrand Russell chapter 11 chapter 11 on intuitive knowledge there is a common impression that everything that we believe ought to be capable of proof or at least of being shown to be highly probable it is felt by many that a belief for which no reason can be given is an unreasonable belief in the main this view is just all our common beliefs are either inferred or capable of being inferred from other beliefs which may be regarded as giving the reason for them as a rule the reason has been forgotten or has even never been consciously present to our minds few of us ever ask ourselves for example what reason there is do you suppose the food we are just going to eat will not turn out to be poison yet we feel when challenged that a perfectly good reason could be found even if we are not ready with it at the moment and in this belief we are usually justified but let us imagine some insistent Socrates who whatever reason we give him continues to demand a reason for the reason we must sooner or later and probably before very long be driven to a point where we cannot find any further reason and where it becomes almost certain that no further reason is even theoretically discoverable starting with the common beliefs of daily life we can be driven back to a point to point until we come to some general principle or some instance of general principle which seems luminously evident and is not itself capable of being deduced from anything more evident in most questions of daily life such as whether our food is likely to be nourishing and not poisonous back to the inductive principle which we discussed in chapter 6 but beyond that there seems to be no further regress the principle itself is constantly used in our reasoning sometimes consciously sometimes unconsciously but there is no reasoning which starting from some simpler self evident principle leads us to the principle of induction as its conclusion and the same holds for other logical principles their truth is evident to us and we employ them in constructing demonstrations but they themselves or at least some of them are incapable of demonstration self-evidence however is not confined to those among general principles which are incapable of proof when a certain number of logical principles have been admitted the rest can be deduced from them but the propositions deduced are often just as self evident as those that were assumed without proof while arithmetic more over can be deduced from the general principles of logic yet the simple propositions of arithmetic such as 2 and 2 are 4 are just as self evident as the principles of logic it would seem also though this is more disputable that there are some self evident ethical principles such as quote we ought to pursue what is good end quote it should be observed that all cases of general principles particular instances dealing with familiar things are more evident than the general principle for example the law of contradiction states that nothing can both have a certain property and not have it this is evident as soon as it is understood but it is not so evident as that a particular which we see cannot be both red and not red it is of course possible that parts of the rose may be red and parts not red or that the rose may be of a shade of pink which we hardly know whether to call red or not but in the former case it is plain that the rose as a whole is not red while in the latter case the answer is theoretically definet as soon as we have decided on a precise definition of quote red it is usually through particular instances that we can be able to see the general principle only those who are practiced in dealing with abstractions can readily grasp a general principle without the help of instances in addition to general principles the other kind of self-evident truths are those immediately derivable from sensation we will call such truths quote truths of perception and the judgments expressing them we will call quote judgments of perception but here a certain amount of care is required in getting at the precise nature of the truths that are self-evident the actual sense data are neither true nor false a particular patch of color which I see for example simply exists it is not the sort of thing that is true or false it is true that there is such a patch true that it has a certain shape and degree of brightness true that it is surrounded by certain other colors but the patch itself like everything else in the world of sense is of a radically different kind from the things that are true or false and therefore cannot properly said to be true thus whatever self-evident truths may be obtained from our senses must be different from the sense data from which they are obtained it would seem that there are two kinds of self-evident truths of perception though perhaps in the last analysis the two kinds may coalesce first there is the kind which simply asserts the existence of the sense datum without in any way analyzing it we see a patch of red and we judge quote there is such and such a patch of red end quote or more strictly quote there is that this is one kind of intuitive judgment of perception the other kind arises when the object of sense is complex and we subject it to some degree of analysis if for instance we see a round patch of red we may judge quote that patch of red is round end quote this is again a judgment of perception but it differs from our previous kind in our present kind we have a single sense datum which has both color and shape the color is red and the shape is round our judgment analyzes the datum into color and shape and then recombines them by stating that the red color is round in shape another example of this kind of judgment is quote this is to the right of that where quote this and quote that are seen simultaneously in this kind of judgment the sense datum contains constituents which have some relation to each other and the judgment asserts that these constituents have this relation another class of intuitive judgments analogous to those of sense and yet quite distinct from them are judgments of memory there is some danger of confusion as to the nature of memory owing to the fact that memory of an object is apt to be accompanied by an image of the object and yet the image cannot be what constitutes memory this is easily seen by merely noticing that the image is in the present whereas what is remembered is known to be in the past moreover we are certainly able to some extent to compare our image with the object remembered so that we often know within somewhat wide limits where our image is accurate but this would be impossible unless the object as opposed to the image were in some way before the mind thus the essence of memory is not constituted by the image but by having immediately before the mind an object which is recognized as past but for the fact of memory in this sense we should not know that there ever was a past at all or should we be able to understand the word quote past any more than a man born blind can understand the word quote light thus there must be intuitive judgments of memory and it is upon them ultimately that all our knowledge of the past depends in the case of memory however raises a difficulty for it is notoriously felitious and thus throws doubt on the trustworthiness of intuitive judgments in general the difficulty is no light one but let us first narrow its scope as far as possible broadly speaking memory is trustworthy in proportion to the vividness of the experience and to its nearness in time if the house next door was struck by lightning half a minute ago my memory of what I saw and heard will be so reliable that it would be preposterous to doubt whether there had been a flash at all and the same applies to less vivid experiences so long as they are recent I am absolutely certain that half a minute ago I was sitting in the same chair in which I am sitting now going backward over the day I find things of which I am quite certain other things of which I am almost certain other things of which I can become certain by thought and by calling upon attendant circumstances and some things of which I am by no means certain I am quite certain that I ate my breakfast this morning but if I were as indifferent to my breakfast as a philosopher should be I should be doubtful as to the conversation at breakfast I can recall some of it easily some with an effort some only with a large element of doubt and some not at all thus there is a continual gradation in the degree of self-evidence of what I remember and a corresponding gradation of the trustworthiness of my memory thus the first answer to the difficulty of the fallacious memory is to say that the memory has degrees of self-evidence and that these correspond to the degrees of its trustworthiness reaching a limit of perfect self-evident and perfect trustworthiness in our memory of events which are recent and vivid it would seem however that there are cases of very firm belief in a memory which is wholly false it is probable that in these cases what is really remembered in the sense of being immediately before the mind is something other than what is falsely believed in though something generally associated with it George IV is said to have at last believed that he was at the battle of Waterloo because he had so often said that he was in this case what was immediately remembered was his repeated assertion belief in what he was asserting if it existed would be produced by association with the remembered assertion and would therefore not be a genuine case of memory it would seem that cases of fallacious memory can probably all be dealt with in this way i.e. they can be shown to be not cases of memory in a strict sense at all one important point about self-evidence is made clear by the case of memory and that is that self-evidence has degrees it is not a quality which is simply present or absent but a quality which may be more or less present in gradations ranging from absolute certainty to most imperceptible faintness truths of perception and some of the principles of logic have the very highest degree of self-evidence truths of immediate memory have an almost equally high degree the inductive principle has less self-evidence than some of the other principles of logic such as quote what follows from a premise must be true and quote memories have a diminishing self-evidence as they become remotor and fainter the truths of logic and mathematics have broadly speaking less self-evidence as they become more complicated judgments of intrinsic ethical or aesthetic value are apt to have some self-evidence but not much degrees of self-evidence are important to the theory of knowledge since if propositions may as seems likely have some degree of self-evidence without being true it will be necessary to abandon all connection between self-evidence and truth but merely to say that where there is a conflict the more self-evident proposition is to be retained and the less self-evident rejected it seems however highly probable that two different notions are combined in quote self-evidence as above explained that one of them which corresponds to the highest degree of self-evidence is really an infallible guarantee of truth while the other which corresponds to all the other degrees does not give an infallible guarantee but only a greater or less presumption this however is only a suggestion which we cannot as yet develop further after we have dealt with the nature of truth we shall return to the subject of self-evidence in connection with the distinction between knowledge and error End of Chapter 11 Recording by Robert Scott mojo-move411.com mojo-move411.com mojo-move411.com mojo-move411.com August the 21st 2007 Chapter 12 of The Problems of Philosophy This is a LibriVox Recording here in the public domain. For more information or to volunteer please visit LibriVox.org The Problems of Philosophy by Bertrand Russell Chapter 12 Truth and Falsehood Our knowledge of truths, unlike our knowledge of things, has an opposite, namely error. So far as things are concerned we may know them or not know them, but there is no positive state of mind which can be described as erroneous knowledge of things so long at any rate as we can find ourselves to knowledge by acquaintance. Whatever we are acquainted with must be something. We may draw wrong inferences from our acquaintance, but the acquaintance itself cannot be deceptive. Thus there is no dualism as regards acquaintance. But as regards knowledge of truths there is a dualism. We may believe what is false as well as what is true. We know that on very many subjects different people hold different and incompatible opinions, hence some beliefs must be erroneous. Since erroneous beliefs are often held just as strongly as true beliefs it becomes a difficult question how they are to be distinguished from true beliefs. How are we to know in a given case that our belief is not erroneous? This is a question of the very greatest difficulty to which no completely satisfactory answer is possible. There is however a preliminary question which is rather less difficult and that is what do we mean by truth and falsehood? It is this preliminary question which is to be considered in this chapter. In this chapter we are not asking how we can know whether belief is true or false. We are asking what is meant by the question whether belief is true or false. It is to be hoped that a clear answer to this question may help us to obtain an answer to the question what beliefs are true, but for the present we ask only what is truth and what is falsehood, not what beliefs are true and what beliefs are false. It is very important to keep these different questions entirely separate since any confusion between them is sure to produce an answer which is not really applicable to either. There are three points to observe in the attempt to discover the nature of truth, three requisites which any theory must fulfill. One, our theory of truth must be such as to admit of its opposite falsehood. A good many philosophers have failed adequately to satisfy this condition. They have constructed theories according to which all our thinking ought to have been true and have then had the greatest difficulty in finding a place for falsehood. In this respect our theory of belief must differ from our theory of acquaintance since in the case of acquaintance it was not necessary to take account of any opposite. Two, it seems fairly evident that if there were no beliefs there could be no falsehood and no truth either in the sense in which truth is falsehood. If we imagine a world of mere matter there would be no room for falsehood in such a world and although it would contain what may be called facts it would not contain any truths in the sense in which truths are things of the same kind as falsehoods. In fact truth and falsehood are properties of beliefs and statements hence a world of mere matter since it would contain no beliefs or statements would also contain no truth or falsehood. Three, but as against what we have just said it is to be observed that the truth or falsehood of a belief always depends outside the belief itself. If I believe that Charles I died on the scaffold I believe truly not because of any intrinsic quality of my belief which could be discovered by merely examining the belief but because of an historical event which happened two and a half centuries ago. If I believe that Charles I died in his bed I believe falsely. No degree of vividness in my belief or of care and arriving at it prevents it from being false again because of what happened long ago and not because of any intrinsic property of my belief. Hence although truth and falsehood are properties of beliefs they are properties dependent upon the relations of the beliefs to other things not upon any internal quality of the beliefs. The third of the above requisites leads us to adopt the view which has on the whole been commonest among philosophers that truth consists in some form of correspondence between belief and fact. It is however by no means an easy matter to discover a form of correspondence to which there are no irrefutable objections. By this partly and partly by the feeling that if truth consists in a correspondence of thought with outside thought, thought can never know when truth has been attained, many philosophers have been led to try to find some definition of truth which shall not consist in relation to something wholly outside belief. The most important attempt at a definition of this sort is the theory that truth consists in coherence. It is said that the mark of falsehood is failure to cohere in the body of our beliefs and that it is the essence of a truth to form part of the completely rounded system which is the truth. There is however a great difficulty in this view or rather two great difficulties. The first is that there is no reason to suppose that only one coherent body of beliefs is possible. It may be that with sufficient imagination a novelist might invent a past for the world that would perfectly fit onto what we know and yet be quite different from the real past. In more scientific matters it is certain that there are often two or more hypotheses which account for all the known facts on some subject and although in such cases men of science endeavor to find facts which will rule out all the hypotheses except one, there is no reason why they should always succeed. In philosophy again it seems not uncommon for two rival hypotheses to be both able to account for all the facts. Thus for example it is possible that life is one long dream and that the outer world has only that degree of reality that the objects of dreams have. But although such a view does not seem inconsistent with known facts, there is no reason to prefer it to the common sense view according to which other people and things do really exist. Thus coherence as the definition of truth fails because there is no proof that there can be only one coherent system. The other objection to this definition of truth is that it assumes the meaning of coherence known whereas in fact coherence presupposes the truth of the laws of logic. Two propositions are coherent when both may be true and are incoherent when one at least must be false. Now in order to know whether two propositions can both be true we must know such truths as the law of contradiction. For example the two propositions this tree is a beach and this tree is not a beach are not coherent because of the law of contradiction. But if the law of contradiction itself were subjected to the test of coherence we should find that if we choose to oppose it false nothing will any longer be incoherent with anything else. Thus the laws of logic supply the skeleton or framework within which the test of coherence applies and they themselves cannot be established by this test. For the above two reasons coherence cannot be accepted as giving the meaning of truth though it is often the most important test of truth after a certain amount of truth has become known. Hence we are given back to correspondence with fact as constituting the nature of truth. It remains to define precisely what we mean by fact and what is the nature of the correspondence which must subsist between belief and fact in order that belief may be true. In accordance with our three requisites we have to seek a theory of truth which one allows truth to have an opposite namely falsehood. Two makes truth a property of beliefs but three makes it a property wholly dependent upon the relation of the beliefs to outside things. The necessity of allowing for falsehood makes it impossible to regard belief as a relation of the mind to a single object which could be said to be what is believed. If belief were so regarded we should find that like acquaintance it would not admit of the opposition of truth and falsehood but would have to be always true. This may be made clear by examples. Othello believes falsely that Desdemona loves Cassio. We cannot say that this belief consists in a relation to a single object Desdemona's love for Cassio for if there were such an object the belief would be true. There is in fact no subject and therefore Othello cannot have any relation to such an object hence his belief cannot possibly consist in a relation to this object. It might be said that his belief is a relation to a different object namely that Desdemona loves Cassio. But it is almost as difficult to suppose that there is such an object as this when Desdemona does not love Cassio as it was to suppose that there is Desdemona's love for Cassio. Hence it will be better to seek for a theory of belief which does not make it consist in a relation of the mind to a single object. It is common to think of relations as though they are always held between two terms but in fact this is not always the case. Some relations demand three terms, some four, and so on. Take for instance the relation between. So long as only two terms come in the relation between is impossible. Three terms are the smallest number that render it possible. York is between London and Edinburgh. But if London and Edinburgh were the only places in the world there could be nothing which was between one place and another. Similarly, jealousy requires three people. There can be no such relation that does not involve three at least. Such a proposition as A wishes B to promote C's marriage with D involves a relation of four terms. That is to say A and B and C and D all come in and the relation involved cannot be expressed otherwise than in a form involving all four. Incidences might be multiplied indefinitely, but enough has been said to show that there are relations which require more than two terms before they can occur. The relation involved in judging or believing must, if falsehood is to be duly allowed for, be taken to be a relation between several terms not between two. When Othello believes that Desdemona loves Cassio, he must not have before his mind a single object, Desdemona's love for Cassio, or that Desdemona loves Cassio, for that would require that there should be objective falsehoods which subsist independently of any minds. And this, though not logically refutable, is a theory to be avoided if possible. Thus it is easier to account for falsehood if we take judgment to be a relation in which the mind and the various objects concerned all occur severally. That is to say, Desdemona and loving and Cassio must all be terms in the relation which subsists when Othello believes that Desdemona loves Cassio. This relation, therefore, is a relation of four terms, since Othello also is one of the terms of the relation. When we say that it is a relation of four terms, we do not mean that Othello has a certain relation to Desdemona and has the same relation to loving and also to Cassio. This may be true of some other relation than believing, but believing plainly is not a relation which Othello has to each of the three terms concerned, but to all of them together. There is only one example of the relation of believing but this one example knits together four terms. Thus the actual occurrence at the moment when Othello is entertaining his belief is that the relation called believing is knitting together into one complex whole the four terms Othello, Desdemona, loving and Cassio. What is called belief or judgment is nothing but this relation of believing or judging which relates a mind to several things other than itself. An act of belief or of judgment is the occurrence between certain terms at some particular time of the relation of believing or judging. We are now in a position to understand what it is that distinguishes a true judgment from a false one. For this purpose we will adopt certain definitions. In every act of judgment there is a mind which judges and there are terms concerning which it judges. We will call the mind the subject in the judgment and the remaining terms the objects. Thus when Othello judges that Desdemona loves Cassio, Othello is the subject while the objects are Desdemona and loving and Cassio. The subject and the objects together are called the constituents of the judgment. It will be observed that the relation of judging has what is called a sense or direction. We may say metaphorically that it puts its objects in a certain order which we may indicate by means of the order of the words in the sentence. In an inflected language the same thing will be indicated by inflections, e.g. by the difference between the mominative and accusative. Othello's judgment that Cassio loves Desdemona differs from his judgment that Desdemona loves Cassio in spite of the fact that it consists of the same constituents in a different order in the two cases. Similarly if Cassio judges that Desdemona loves Othello the constituents of the judgment are still the same but their order is different. This property of having a sense or direction is one which the relation of judging shares with all other relations. The sense of relations is the ultimate source of order in series and a host of mathematical concepts but we need not concern ourselves further with this aspect. We spoke of the relation called judging or believing as knitting together into one complex whole, the subject and the objects. In this respect judging is exactly like every other relation. Whenever a relation holds between two or more terms it unites the terms into a complex whole. If Othello loves Desdemona there is such a complex whole as Othello's love for Desdemona. The terms united by the relation may be themselves complex or may be simple but the whole which results from there being united must be complex. Wherever there is a relation which relates certain terms there is a complex object formed of the union of those terms. Wherever there is a complex object there is a relation which relates its constituents. When an act of believing occurs there is a complex in which believing is the uniting relation and subject and objects are arranged in a certain order by the sense of the relation of believing. Among the objects as we saw in considering Othello believes that Desdemona loves Casio one must be in a relation in this instance the relation loving. But this relation as it occurs in the act of believing is not the relation which creates the unity of the complex whole consisting of the object and the objects. The relation loving as it occurs in the act of believing is one of the objects. It is a brick in the structure not the cement. The cement is the relation believing. When the belief is true there is another complex unity in which the relation which was one of the objects of the belief relates the other objects. Thus e.g. if Othello believes truly that Desdemona loves Casio then there is a complex unity Desdemona's love for Casio which is composed exclusively of the objects of the belief in the same order as they had in the belief with the relation which was one of the objects occurring now as the cement that binds together the other objects of the belief. On the other hand when a belief is false there is no such complex unity composed only of the objects of the belief. If Othello believes falsely that Desdemona loves Casio then there is no such complex unity as Desdemona's love for Casio. Thus a belief is true when it corresponds to a certain associated complex and false when it does not. Assuming for the sake of definiteness that the objects of the belief are two terms and a relation the terms being put in a certain order by the sense of believing then if the two terms in that order are united by the relation into a complex the belief is true if not it is false. This constitutes the definition of truth and falsehood that we were in search of judging or believing as a certain complex unity of which a mind is a constituent. If the remaining constituents taken in the order which they have in a belief form a complex unity then a belief is true. If not it is false. Thus although truth and falsehood are properties of beliefs yet they are in a sense extrinsic properties for the condition of the truth of a belief is something not involving beliefs or in general any mind at all but only the objects of the belief. A mind which believes believes truly when there is a corresponding complex not involving the mind but only its objects. This correspondence ensures truth and its absence entails falsehood. Hence we account simultaneously for facts that believes A. depend on their minds for their existence. B. do not depend on minds for their truth. We may restate our theory as follows. If we take such a belief as Othello believes that Desdemona loves Casio we will call Desdemona and Casio the object terms and loving the object relation. If there is a complex unity Desdemona is allowed for Casio consisting of the object terms related by the object relation in the same order as they have in the belief then this complex unity is called the fact corresponding to the belief. Thus a belief is true when there is a corresponding fact and is false when there is no corresponding fact. It will be seen that minds do not create truth or falsehood. They create beliefs but when once the beliefs are created the mind cannot make them true or false except in the special case where they concern future things which are within the power of the person believing such as catching trains. What makes a belief true is a fact and this fact does not accept in exceptional cases in any way involve the mind of the person who has the belief. Having now decided what we mean by truth and falsehood we have next to consider what ways there are of knowing whether this or that belief is true or false. This consideration will occupy the next chapter. End of Chapter 12 Chapter 13 of The Problems of Philosophy This is a LibriVox recording. All LibriVox recordings are in the public domain for more information or to find out how to volunteer please contact LibriVox.org The Problems of Philosophy by Bertrand Russell Chapter 13 Knowledge, Error and Probable Opinion The question as to what we mean by truth and falsehood which we considered in the preceding chapter is of much less interest than the question as to how we can know what is true and what is false. This question will occupy us in the present chapter. There can be no doubt that some of our beliefs are erroneous. Thus we are led to inquire what certainty we can ever have that such and such a belief is not erroneous. In other words, can we ever know anything at all? Or do we merely sometimes by good luck believe what is true? Before we can attack this question we must however first decide what we mean by knowing and this question is not so easy as might be supposed. At first sight we might imagine that knowledge could be defined as true belief. When what we believe is true it might be supposed that we had achieved a knowledge of what we believe but this would not accord with the way in which the word is commonly used. To take a very trivial instance if a man believes that the late prime minister's last name began with a B he believes what is true since the late prime minister was Sir Henry Campbell Bannerman but if he believes that Mr. Balfour was the late prime minister he will still believe that the late prime minister's last name began with a B yet this belief, though true would not be thought to constitute knowledge. If a newspaper by an intelligent anticipation announces the result of a battle before any telegram giving the result has been received it may by good fortune announce what afterwards turns out to be the right result and it may produce belief in some of its less experienced readers but in spite of the truth of their belief they cannot be said to have knowledge thus it is clear that a true belief is not knowledge when it is deduced from a false belief. In like manner a true belief cannot be called knowledge when it is deduced by a fallacious process of reasoning even if the premises from which it is deduced are true if I know that all Greeks are men and that Socrates was a man and I infer that Socrates was a Greek I cannot be said to know that Socrates was a Greek because although my premises and my conclusion are true the conclusion does not follow from the premises but are we to say that nothing is knowledge except what is validly deduced from true premises? Obviously we cannot say this such a definition is at once too wide and too narrow in the first place it is too wide because it is not enough that our premises should be true they must also be known the man who believes that Mr. Balfour was the late prime minister may proceed to draw valid deductions from the true premise that the late prime minister's name began with a B but he cannot be said to know the conclusions reached by these deductions thus we shall have to amend our definition by saying that knowledge is what is validly deduced from known premises this however is a circular definition it assumes that we already know what is met by known premises it can therefore at best define one sort of knowledge the sort we call derivative as opposed to intuitive knowledge we may say derivative knowledge is what is validly deduced from premises known intuitively in this statement there is no formal defect but it leaves the definition of intuitive knowledge still to seek leaving on one side for the moment the question of intuitive knowledge let us consider the above suggested definition of derivative knowledge the chief objection to it is that it unduly limits knowledge it constantly happens that people entertain a true belief which has grown up in them because of some piece of intuitive knowledge from which it is capable of being validly inferred but from which it has not as a matter of fact been inferred by any logical process take for example the beliefs produced by reading if the newspapers announce the death of the king we are fairly well justified in believing that the king is dead since this sort of announcement which would not be made if it were false and we are quite amply justified in believing that the newspaper asserts that the king is dead but here the intuitive knowledge upon which our belief is based is knowledge of the existence of sense data derived from looking at the print which gives the news this knowledge scarcely rises into consciousness except in a person who cannot read easily a child may be aware of the shapes of the letters and pass gradually and painfully to a realization of their meaning but anybody accustomed to reading passes it once to what the letters mean and is not aware that he has derived this knowledge from the sense data called seeing the printed letters thus although a valid inference from the letters to their meaning is possible and could be performed by the reader it is not in fact performed since he does not in fact perform any operation which can be called logical inference yet it would be absurd to say that the reader does not know that the newspaper announces the king's death we must therefore admit his derivative knowledge whatever is the result of intuitive knowledge even if by mere association provided there is a valid logical connection and the person in question could become aware of this connection by reflection there are in fact many ways besides logical inference by which we pass from one belief to another the passage from the print to its meaning illustrates these ways these ways may be called psychological inference we shall then admit such psychological inference as a means of obtaining derivative knowledge provided there is a discoverable logical inference which runs parallel to the psychological inference this renders our definition of derivative knowledge less precise than we could wish since the word discoverable is vague it does not tell us how much reflection is needed in order to make the discovery but in fact knowledge is not a precise conception it merges into probable opinion as we shall see more fully in the course of the present chapter a very precise definition therefore should not be sought since any such definition must be more or less misleading the chief difficulty in regard to knowledge however does not arise over derivative knowledge but over intuitive knowledge so long as we are dealing with derivative knowledge we have the test of intuitive knowledge to fall back upon but in regard to intuitive beliefs it is by no means easy to discover any criterion by which to distinguish some is true and others is erroneous in this question it is scarcely possible to reach any very precise result all our knowledge of truths is infected with some degree of doubt and a theory which ignored this fact would be plainly wrong something may be done however to mitigate the difficulties of the question our theory of truth to begin with supplies the possibility of distinguishing certain truths as self-evident in a sense which ensures infallibility when a belief is true we said there is a corresponding fact in which the several objects of the belief form a single complex the belief is said to constitute knowledge of this fact provided it fulfills those further somewhat vague conditions which we have been considering in the present chapter but in regard to any fact besides the knowledge constituted by belief we may also have the kind of knowledge constituted by perception taking this word in its widest possible sense for example if you know the hour of the sunset you can at that hour know the fact that the sun is setting this is knowledge of the fact by way of knowledge of truths but you can also if the weather is fine look to the west and actually see the setting sun you then know the same fact by the way of knowledge of things thus in regard to any complex fact there are theoretically which it may be known 1. by means of a judgment in which its several parts are judged to be related as they are in fact related 2. by means of acquaintance with the complex fact itself which may in a large sense be called perception though it is by no means confined to objects of the senses now we'll be observed that the second way of knowing a complex fact the way of acquaintance is only possible when there really is such a fact while the first way, like all judgment is liable to error the second way gives us the complex whole and is therefore only possible when its parts do actually have that relation which makes them combine to form such a complex the first way on the contrary gives us the parts and the relation and demands only the reality of the parts and the relation the relation may not relate those parts in that way and yet the judgment may occur it will be remembered that at the end of chapter 11 we suggested that there might be two kinds of self-evidence one giving an absolute guarantee of truth the other only a partial guarantee these two kinds can now be distinguished we may say that a truth is self-evident in the first and most absolute sense when we have acquaintance with the fact which corresponds to the truth when Othello believes that Desdemona loves Casio the corresponding fact if his belief were true would be Desdemona's love for Casio this would be a fact with which no one could have acquaintance except Desdemona hence in the sense of self-evidence that we are considering the truth that Desdemona loves Casio if it were a truth could only be self-evident to Desdemona all mental facts and all facts concerning sense data have the same privacy if there is only one person to whom they can be self-evident in our present sense since there is only one person who can be acquainted with the mental things or the sense data concerned thus no fact about any particular existing thing can be self-evident to more than one person on the other hand facts about universals do not have this privacy many minds may be acquainted with the same universals hence a relation between universals may be known by acquaintance to many different people in all cases where we know by acquaintance a complex fact consisting of certain terms in a certain relation we say that the truth that these terms are so related has the first or absolute kind of self-evidence and in these cases the judgment that the terms are so related must be true thus this sort of self-evidence is an absolute guarantee of truth but although this sort of self-evidence is an absolute guarantee of truth it does not enable us to be absolutely certain in the case of any given judgment that the judgment in question is true suppose we first perceive the sun shining which is a complex fact and then proceed to make the judgment the sun is shining in passing from the perception to the judgment it is necessary to analyze the given complex fact we have to separate out the sun and shining as constituents of the fact in this process it is possible to commit an error hence even where a fact has the first or absolute kind of self-evidence a judgment believed to correspond to the fact is not absolutely infallible because it may not really correspond to the fact but if it does correspond in the sense explained in the preceding chapter then it must be true the second sort of self-evidence will be that which belongs to judgments in the first instance and is not derived from direct perception of a fact as a single complex whole this second kind of self-evidence will have degrees from the very highest degree down to a bare inclination in favor of the belief take for example the case of a horse trotting away from us along a hard road at first our certainty that we hear the hooves is complete gradually if we listen intently there comes a moment when we think perhaps it was imagination or the blind upstairs or our own heartbeats at last we become doubtful whether there was any noise at all then we think we no longer hear anything and at last we know we no longer hear anything in this process there is a continual gradation of self-evidence from three to the least not in the sense dated themselves but in the judgments based on them or again suppose we are comparing two shades of color one blue and one green we can be quite sure they are different shades of color but if the green color is gradually altered to be more and more like the blue becoming first a blue green then a greeny blue then blue but when we are doubtful whether we can see any difference and then a moment when we know that we cannot see any difference the same thing happens in tuning a musical instrument or in any other case where there is a continuous gradation thus self-evidence of this sort is a matter of degree and it seems plain that the higher degrees are more to be trusted than the lower degrees in derivative knowledge our ultimate premises must have some degree of self-evidence and so must their connection with the conclusions deduced from them take for example a piece of reasoning in geometry it is not enough that the axioms from which we start should be self-evident it is necessary also that at each step in the reasoning the connection of the premise and conclusion should be self-evident in difficult reasoning this connection has often only a small degree of self-evidence hence errors of reasoning are not improbable where the difficulty is great from what has been said it is evident that both as regards intuitive knowledge and as regards derivative knowledge if we assume that intuitive knowledge is trustworthy in proportion to the degree of self-evidence there will be a gradation in trustworthiness from the existence of noteworthy sense data and the simpler truths of logic and arithmetic which may be taken as quite certain down to judgments which seem only just more probable than their opposites what we firmly believe if it is true is called knowledge provided it is either intuitive or inferred logically or psychologically from intuitive knowledge from which it follows logically what we firmly believe if it is not true is called error what we firmly believe if it is neither knowledge nor error and also what we believe hesitatingly because it is or is derived from something which is not the highest degree of self-evidence may be called probable opinion thus the greater part of what would commonly pass as knowledge is more or less probable opinion in regard to probable opinion we derive great assistance from coherence which we rejected as the definition of truth but may often use as a criterion a body of individually probable opinions if they are mutually coherent become more probable than any one of them would be individually it is in this way that many scientific hypotheses acquire their probability they fit into a coherent system of probable opinions and thus become more probable than they would be in isolation the same thing applies to general philosophical hypotheses often in a single case such hypotheses may seem highly doubtful while yet when we consider the order and coherence which they introduce into a massive probable opinion they become pretty nearly certain this applies in particular to such matters as the distinction between dreams and waking life if our dreams night after night were as coherent one with another as our days we should hardly know whether to believe the dreams or the waking life as it is the test of coherence condemns the dreams and confirms the waking life but this test though it increases probability where it is successful never gives absolute certainty unless there is certainty already at some point in the coherent system thus the mere organization of probable opinion will never by itself transform it into indubitable knowledge end of chapter 13 this recording is in the public domain this is a LibriVox recording all LibriVox recordings are in the public domain for more information or to volunteer please visit LibriVox.org the problems of philosophy by Bertrand Russell chapter 14 the limits of philosophical knowledge read by Jacob Miller and all that we have said hitherto concerning philosophy was scarcely touched on many matters that occupy great space in the writings of most philosophers most philosophers, or at any rate very many, profess to be able to prove by a priori metaphysical reasoning such things as the fundamental dogmas of religion the essential rationality of the universe the illusoriness of matter the unreality of all evil and so on there can be no doubt that the hope of finding reason to believe such theses as these has been the chief inspiration of many lifelong students of philosophy this hope I believe is vain it would seem that knowledge concerning the universe as a whole is not to be obtained by metaphysics and that the proposed proves that in virtue of the laws of logic such and such things must exist and such and such others cannot are not capable of surviving a critical scrutiny in this chapter we shall briefly consider the kind of way in which such reasoning is attempted with a view to discovering whether we can hope that it may be valid the great representative in modern times of this kind of view which we wish to examine was Hegel 1770-1831 Hegel's philosophy is very difficult and commentators differ as to the true interpretation of it according to the interpretation I shall adopt which is that of many if not most of the commentators and has the merit of giving an interesting and important type of philosophy his main thesis is that everything short of the whole is obviously fragmentary and obviously incapable of existing without the compliment supplied by the rest of the world just as a comparative anatomist from a single bone sees what kind of animal the whole must have been so the metaphysician according to Hegel sees from any one piece of reality what the whole of reality must be at least in its large outlines every apparently separate piece of reality has as it were hooks which grapple it to the next piece the next piece in turn has fresh hooks and so on until the whole universe is reconstructed this essential incompleteness appears according to Hegel equally in the world of thought and in the world of things in the world of thought if we take any idea which is abstract or incomplete we find on examination that if we forget its incompleteness we become involved in contradictions these contradictions turn the idea in question into its opposite or antithesis and in order to escape we have to find new less incomplete idea which is the synthesis of our original idea and its antithesis this new idea though less incomplete than the idea we started with will be found nevertheless to be still not wholly complete but to pass into its antithesis with which it must be combined in a new synthesis in this way Hegel advances until he reaches the absolute idea which according to him has no incompleteness no opposite and no need for the development the absolute idea therefore is adequate to describe absolute reality but all lower ideas only describe absolute reality as it appears to a partial view not as it is to one who simultaneously surveys the whole thus Hegel reaches the conclusion that absolute reality forms one single harmonious system not in space or time not in any degree evil wholly rational and wholly spiritual any appearance to the contrary in the world we know can be proved logically so he believes to be entirely due to our fragmentary piecemeal view of the universe if we saw the universe whole as we may suppose God sees it space and time and matter and evil and all striving and struggling would disappear and we would see instead an eternal perfect unchanging spiritual unity in this conception there is undeniably something sublime something to which we could wish to yield ascent nevertheless when the arguments and support of it are carefully examined there is confusion and many unwarrantable assumptions the fundamental tenet upon which the system is built up is that what is incomplete must be not self-subsistent but must need the support of other things before it can exist it is held that whatever has relations to things outside itself must contain some reference to those outside things in its own nature and could not therefore be what it is if those outside things did not exist a man's nature for example was created by his memories and the rest of his knowledge by his loves and hatred so on thus, but for the objects which he knows or loves or hates he could not be what he is he is essentially and obviously a fragment taken as the sum total of reality he would be self-contradictory this whole point of view however turns upon the notion of the nature of a thing which seems to mean all the truth about the thing it is of course the case that a truth which connects one thing with another thing could not subsist if the other thing did not subsist but a truth about a thing is not part of the thing itself although it must according to the above usage be part of the nature of the thing if we mean by a thing's nature all the truth about the thing then plainly we cannot know a thing's nature unless we know all the things relations to all other things in the universe but if the word nature is used in this sense we shall have to hold that the thing may be known when its nature is not known or at any rate is not known completely there is a confusion when this use of the word nature is employed between knowledge of things and knowledge of truths we may have knowledge of a thing by acquaintance even if we know very few propositions about it theoretically we need not know any propositions about it thus, acquaintance with a thing does not involve knowledge of its nature in the above sense and although acquaintance with a thing is involved in our knowing any one proposition about a thing knowledge of its nature in the above sense is not involved hence one acquaintance with a thing does not logically involve a knowledge of its relations and two a knowledge of some of its relations does not involve a knowledge of all of its relations nor a knowledge of its nature in the above sense I may be acquainted for example my toothache, and this knowledge may be as complete as knowledge by acquaintance ever can be, without knowing all that the dentist, who is not acquainted with it, can tell me about its cause, and without, therefore, knowing its nature in the above sense. Thus the fact that a thing has relations does not prove that its relations are logically necessary. That is to say, from the mere fact that it is the thing it is, we cannot deduce that it must have the various relations which in fact it has. This only seems to follow, because we know it already. It follows that we cannot prove that the universe as a whole forms a single, harmonious system, such as Hegel believes that it forms. And if we cannot prove this, we also cannot prove the unreality of space and time, and matter, and evil. For this is deduced by Hegel from the fragmentary and relational character of these things. Thus we are left to the piecemeal investigation of the world, and are unable to know the characters of those parts of the universe that are remote from our experience. This result, disappointing as it is to those whose hopes have been raised by the systems of philosophers, is in harmony with the inductive and scientific temper of our age, and is borne out by the whole examination of human knowledge which has occupied our previous chapters. Most of the great ambitious attempts of metaphysicians have preceded by the attempts to prove that such and such apparent features of the actual world were self-contradictory, and therefore could not be real. The whole tendency of modern thought, however, is more and more in the direction of showing that the supposed contradictions were illusory, and that very little can be proved a priori from considerations of what must be. A good illustration of this is afforded by space and time. Space and time appear to be infinite in extent, and infinitely divisible. If we travel along a straight line in either direction, it is difficult to believe that we shall finally reach a last point, beyond which there is nothing not even empty space. Similarly, if in imagination we travel backwards or forwards in time, it is difficult to believe that we shall reach a first or last time, with not even empty time beyond it. Thus space and time appear to be infinite in extent. Again, if we take any two points on a line, it seems evident that there must be other points between them, however small the distance between them may be. Every distance can be halved, and the halves can be halved again, and so on, at infinitum. In time, similarly, however little time may elapse between two moments, it seems evident that there will be other moments between them. Thus, space and time appear to be infinitely divisible. But as against these apparent facts, infinite extent and infinite divisibility, philosophers have advanced arguments tending to show that there could be no infinite collections of things, and that therefore the number of points in space, or of instants in time, must be finite. Thus a contradiction emerged between the apparent nature of space and time, and the supposed impossibility of infinite collections. Kant, who first emphasized this contradiction, deduced the impossibility of space and time, which he declared to be merely subjective. But since his time, very many philosophers have believed that space and time are mere appearance, not characteristic of the world as it really is. Now, however, owing to the labors of the mathematicians, notably Georg Kantor, it has appeared that the impossibility of infinite collections was a mistake. They are not, in fact, self-contradictory, but only contradictory of certain rather obstinate mental prejudices. Hence the reason for regarding space and time as unreal have become inoperative, and one of the great sources of metaphysical constructions is dried up. The mathematicians, however, have not been content with showing that space, as it is commonly supposed to be, is possible. They have shown also that many other forms of space are equally possible, so far as logic can show. Some of Euclid's axioms, which appear to common sense to be necessary, and were formally supposed to be necessary by philosophers, are now known to derive their appearance of necessity from our mere familiarity with the actual space, and not from any a priori logical foundation. By imagining worlds in which these axioms are false, the mathematicians have used logic to loosen the prejudices of common sense, and to show the possibility of spaces differing, some more, some less, from that in which we live. And some of these spaces differ so little from Euclidean space, or distances such as we can measure are concerned, that it is impossible to discover by observation whether our actual space is strictly Euclidean, or one of these other kinds. Thus the position is completely reversed. Formally it appeared that experience left only one kind of space to logic, and logic showed this one kind to be impossible. Now logic presents many kinds of space as possible apart from experience, and experience only partially decides between them. Thus, while our knowledge of what is has become less than it was formally supposed to be, our knowledge of what may be is enormously increased. Instead of being shot in within narrow walls of which every nook and cranny could be explored, we find ourselves in an open world of free possibilities, where much remains unknown because there is so much to know. What has happened in the case of space and time has happened to some extent in other directions as well. The attempt to prescribe to the universe by means of a priori principles has broken down. Logic instead of being as formally, the bar to possibilities, has become the great liberator of the imagination, presenting innumerable alternatives which are closed to unreflective common sense, and leaving to experience the task of deciding where decision is possible between the many worlds which logic offers for our choice. Thus knowledge as to what exists becomes limited to what we can learn from experience, not to what we can actually experience. For as we have seen there is much knowledge by description concerning things of which we have no direct experience. But in all cases of knowledge by description we need some connection of universals enabling us from such and such a datum to infer an object of a certain sort as implied by our datum. Thus in regard to physical objects, for example, the principle that since data are signs of physical objects is itself a connection of universals, and it is only in virtue of this principle that experience enables us to acquire knowledge concerning physical objects. The same applies to the law of causality, or to descend to what is less general to such principles as the law of gravitation. Principles such as the law of gravitation are proved, or rather are rendered highly probable, by a combination of experience with some wholly a priori principle, such as the principle of induction. Thus our intuitive knowledge, which is the source of all our other knowledge of truth, is of two sorts. Pure empirical knowledge, which tells us of the existence of some of the properties of particular things with which we are acquainted, and pure a priori knowledge, which gives us connections between universals and enables us to draw inferences from the particular facts given in empirical knowledge. Our derivative knowledge always depends upon some pure a priori knowledge, and usually also depends upon some pure empirical knowledge. Philosophical knowledge, if what has been said above is true, does not differ essentially from scientific knowledge. There's no special source of wisdom, which is open to philosophy, but not to science, and the results obtained by philosophy are not radically different from those obtained from science. The essential characteristic of philosophy, which makes it a study distinct from science, is criticism. It examines critically the principles employed in science and in daily life, and searches out any inconsistencies there may be in these principles, and it only accepts them when, as a result of a critical inquiry, no reason for rejecting them has appeared. If, as many philosophers have believed the principles underlying the sciences were capable, when disengaged from irrelevant detail, of giving us knowledge concerning the universe as a whole, such knowledge would have the same claim on our belief as scientific knowledge has. But our inquiry has not revealed any such knowledge, and therefore, as regards the special doctrines of the bolder metaphysicians, has had a mainly negative result. But as regards what would be commonly accepted as knowledge, our result is in the main positive. We have seldom found reason to reject such knowledge as the result of our criticism, and we have seen no reason to suppose men incapable of the kind of knowledge which he is generally believed to possess. When, however, we speak of philosophy as a criticism of knowledge, it is necessary to impose a certain limitation. If we adopt the attitude of the complete skeptic, placing ourselves wholly outside all knowledge, and asking from this outside position to be compelled to return within the circle of knowledge, we are demanding what is impossible, and our skepticism can never be refuted. For all refutation must begin with some piece of knowledge which the disputants share. From blank doubt no argument can begin. Hence the criticism of knowledge, which philosophy employs, must not be of this destructive kind, if any result has to be achieved. Against this absolute skepticism no logical argument can be advanced. But it is not difficult to see that skepticism of this kind is unreasonable. Descartes' methodical doubt, with which modern philosophy began, is not of this kind, but is rather the kind of criticism which we are asserting to be the essence of philosophy. His methodical doubt consisted in end doubting whatever seemed doubtful, in pausing with each apparent piece of knowledge to ask himself whether, on reflection, he could feel certain that he really knew it. This is the kind of criticism which constitutes philosophy. Some knowledge, such as the knowledge of the existence of our sense data, appears quite indubitable, however calmly and thoroughly we reflect upon it. In regard to such knowledge, philosophical criticism does not require that we should abstain from belief. But there are beliefs, such for example, as the belief that physical objects exactly resemble our sense data, which are entertained until we begin to reflect, but are found to melt away when subjected to a close inquiry. Such beliefs philosophy will bid us reject, unless a new line of argument is found to support them. But to reject the beliefs which do not appear open to any objections, however closely we examine them, is not reasonable, and is not what philosophy advocates. The criticism aimed at, in a word, is not that which, without reason, determines to reject, but that which considers each piece of apparent knowledge on its merits and retains whatever still appears to be knowledge when this consideration is completed. That some risk of error remains must be admitted, since human beings are fallible. Philosophy may claim justly that it diminishes the risk of error, and that in some cases it renders the risk so small as to be practically negligible. To do more than this is not possible in a world where mistakes must occur. And more than this, no prudent advocate of philosophy would claim to have performed. End of Chapter 14 of The Problems of Philosophy by Bertrand Russell. Chapter 15 of The Problems of Philosophy. This is a LibriVox recording. All LibriVox recordings are in the public domain. For more information or to volunteer, please visit LibriVox.org. Recording by Leon Meyer. The Problems of Philosophy by Bertrand Russell. Chapter 15. The Value of Philosophy. Having now come to the end of our brief and very incomplete review of The Problems of Philosophy, it will be well to consider, in conclusion, what is the value of philosophy and why it ought to be studied. It is the more necessary to consider this question in view of the fact that many men, under the influence of science or of practical affairs, are inclined to doubt whether philosophy is anything better than innocent but useless trifling, hair splitting distinctions, and controversies on matters concerning which knowledge is impossible. This view of philosophy appears to result partly from a wrong conception of the ends of life, partly from a wrong conception of the kinds of goods which philosophy strives to achieve. Physical science, through the medium of inventions, is useful to innumerable people who are wholly ignorant of it. Thus, the study of physical science is to be recommended not only or primarily because of the effect on the student, but rather because of the effect on mankind in general. Thus, utility does not belong to philosophy. If the study of philosophy has any value at all for others, then students of philosophy, it must be only indirectly, through its effects upon the lives of those who study it. It is in these effects, therefore, if anywhere, that the value of philosophy must be primarily sought. But further, if we are not to fail in our endeavor to determine the value of philosophy, we must first free our minds from the prejudices of what are wrongly called practical men. The practical men, as this word is often used, is one who recognizes only material needs, who realizes that men must have food for the body but is oblivious of the necessity of providing food for the mind. If all men were well off, if poverty and disease had been reduced to the lowest possible point, there would still remain much to be done to produce a valuable society. And even in the existing world, the goods of the mind are at least as important as the goods of the body. It is exclusively among the goods of the mind that the value of philosophy is to be found. And only those who are not indifferent to these goods can be persuaded that the study of philosophy is not a waste of time. Philosophy, like all other studies, aims primarily at knowledge. The knowledge it aims at is the kind of knowledge which gives unity and system to the body of the sciences, and the kind which results from a critical examination of the grounds of our convictions, prejudices, and beliefs. But it cannot be maintained that philosophy has had any very great measure of success in its attempts to provide definite answers to its questions. If you ask a mathematician, a mineralogist, a historian, or any other man of learning, what definite body of truth has been ascertained by his science, his answer will last as long as you're willing to listen. But if you put the same question to a philosopher, he will, if he is candid, have to confess that his study has not achieved positive results such as have been achieved by other sciences. It is true that this is partly accounted for by the fact that, as soon as definite knowledge concerning any subject becomes possible, this subject ceases to be called philosophy, and becomes a separate science. The whole study of the heavens, which now belongs to astronomy, was once included in philosophy. Newton's great work was called the mathematical principles of natural philosophy. Similarly, the study of the human mind, which was a part of philosophy, has now become separated from philosophy and has become the science of psychology. Thus, to a great extent, the uncertainty of philosophy is more apparent than real. Those questions which are already capable of definite answers are placed in the sciences. While those only to which, at present, no definite answer can be given, remain to form the residue which is called philosophy. This is, however, only a part of the truth concerning the uncertainty of philosophy. There are many questions, and among them, those that are the profoundest interest to our spiritual life, which, so far as we can see, must remain insoluble to the human intellect unless its powers become of a quite different order from what they are now. Has the universe any unity of plan or purpose, or is it a fortuitous concourse of atoms? Is consciousness a permanent part of the universe, giving hope of indefinite growth and wisdom? Or is it a transitory accident on a small planet on which life must ultimately become impossible? Are good and evil of importance to the universe or only to man? Such questions are asked by philosophy and variously answered by various philosophers. But it would seem that, whether answers be otherwise discoverable or not, the answers suggested by philosophy are none of them demonstrably true. Yet, however slight may be the hope of discovering an answer, it is part of the business of philosophy to continue the consideration of such questions, to make us aware of their importance, to examine all the approaches to them, and to keep alive that speculative interest in the universe which is apt to be killed by confiding ourselves to definitely ascertainable knowledge. Many philosophers, it is true, have held that philosophy could establish the truth of certain answers to such fundamental questions. They have supposed that what is of most importance in religious beliefs could be proved by strict demonstration to be true. In order to judge of such attempts, it is necessary to take a survey of human knowledge and to form an opinion as to its methods and its limitations. On such a subject it would be unwise to pronounce dogmatically, but if the investigations of our previous chapters have not led us astray, we shall be compelled to renounce the hope of finding philosophical proofs of religious beliefs. We cannot, therefore, include as part of the value of philosophy any definite set of answers to such questions. Hence, once more, the value of philosophy must not depend upon any supposed body of definitely ascertainable knowledge to be acquired by those who study it. The value of philosophy is, in fact, to be sought largely in its very uncertainty. The man who has no tincture of philosophy goes through life imprisoned in the prejudices derived from common sins, from the habitual beliefs of his age or his nation, and from convictions which have grown up in his mind without the cooperation or consent of his deliberate reason. To such a man, the world tends to become definite, finite, obvious. Common objects rouse no questions, and unfamiliar possibilities are contemptuously rejected. As soon as we begin to philosophize, on the contrary, we find, as we saw in our opening chapters, that even the most everyday things lead to problems to which only very incomplete answers can be given. Philosophy, though unable to tell us with certainty what is the true answer to the doubts which it raises, is able to suggest many possibilities which enlarge in our thoughts and free them from the tyranny of custom. Thus, while diminishing our feeling of certainty as to what things are, it greatly increases our knowledge as to what they may be. It removes the somewhat arrogant dogmatism of those who have never traveled into the region of liberating doubt, and it keeps alive our sense of wonder by showing familiar things in an unfamiliar aspect. Apart from its utility in showing unsuspected possibilities, philosophy has a value, perhaps its chief value, through the greatness of the objects which it contemplates, and the freedom from narrow and personal aims resulting from this contemplation. The life of the instinctive man is shut up within the circle of his private interests. Family and friends may be included, but the outer world is not regarded, except as it may help or hinder what comes within the circle of instinctive wishes. In such a life there is something feverish and confined, in comparison with which the philosophic life is calm and free. The private world of instinctive interests is a small one, set in the midst of a great and powerful world which must, sooner or later, lay our private world in ruins. Unless we can so enlarge our interests, as to include the whole outer world, we remain like a garrison and a beleaguered fortress, knowing that the enemy prevents escape and that ultimate surrender is inevitable. In such a life there is no peace, but a constant strife between the insistence of desire and the powerlessness of will. In one way or another, if our life is to be great and free, we must escape this prison and this strife. One way of escape is by philosophic contemplation. Philosophic contemplation does not, in its widest survey, divide the universe into two hostile camps, friends and foes, helpful and hostile, good and bad. It views the whole impartially. Philosophic contemplation, when it is unalloyed, does not aim at proving that the rest of the universe is akin to man. All acquisition of knowledge is an enlargement of the self, but this enlargement is best attained when it is not directly sought. It is obtained when the desire for knowledge is a lone operative, by a study which does not wish in advance that its objects should have this or that character, but adapts the self to the characters which it finds in its objects. This enlargement of self is not obtained when, taking the self as it is, we try to show that the world is so similar to the self that knowledge of it is possible without any admission of what seems alien. The desire to prove this is a form of self-assertion and, like all self-assertion, it is an obstacle to the growth of self which it desires, and of which the self knows that it is capable. Views the world as a means to its own ends. Thus it makes the world of less account than self, and the self sets boundaries to the greatness of its goods. In contemplation, on the contrary, we start from the not-self, and through its greatness the boundaries of self are enlarged, through the infinity of the universe the mind which contemplates it achieves some share in infinity. For this reason, greatness of soul is not fostered by those philosophies which assimilate the universe to man. Knowledge is a form of union of self and not self. Like all union, it is impaired by dominion, and therefore by any attempt to force the universe into conformity with what we find in ourselves. There is a widespread philosophical tendency towards the view which tells us that man is the measure of all things, that truth is man-made, that space and time and the world of universals are properties of the mind, and that if there be anything not created by the mind it is unknowable and of no account for us. This view, if our previous discussions are correct, is untrue, but in addition to being untrue it has the effect of robbing philosophical contemplation of all that gives it value, since it fetters contemplation to self. What it calls knowledge is not a union with the not-self, but a set of prejudices, habits and desires, making an impenetrable veil between us and the world beyond. The man who finds pleasure in such a theory of knowledge is like the man who never leaves the domestic circle for fear his word might not be law. The true philosophical contemplation, on the contrary, finds its satisfaction in every enlargement of the not-self, in everything that magnifies the objects contemplated, and thereby in the subject contemplating. Everything and contemplation that is personal or private, everything that depends upon habit, self-interest or desire, distorts the object, and hence impairs the union which the intellect seeks. By thus making a barrier between subject and object, such personal and private things become a prison to the intellect. The free intellect will see as God might see, without a here and now, without hopes and fears, without the trammels of customary beliefs and traditional prejudices, commonly, dispassionately, and a soul and exclusive desire of knowledge, knowledge as impersonal, as purely contemplated, as it is possible for man to attain. Hence, also, the free intellect will value more the abstract and universal knowledge into which the accidents of private history do not enter, than the knowledge brought by the senses, and dependent, as such knowledge must be, upon an exclusive and personal point of view, and a body whose sense organs distort as much as they reveal. The mind which has become accustomed to the freedom and impartiality of philosophical contemplation will preserve something of the same freedom and impartiality in the world of action and emotion. It will view its purposes and desires as parts of the whole, with the absence of insistence that results from seeing them as infinitesimal fragments, and a world of which all the rest is unaffected by anyone man's deeds. The impartiality which, in contemplation, is the unalloyed desire for truth, is the very same quality of mind which, in action, is justice, and in emotion is that universal love which can be given to all, and not only to those who are judged useful or admirable. The contemplation enlarges not only the objects of our thoughts, but also the objects of our actions and our affections. It makes us citizens of the universe, not only of one walled city at war with all the rest. In this citizenship of the universe consists man's true freedom, and his liberation from the thralldom of narrow hopes and fears. Thus, to some upper discussion, the value of philosophy. Philosophy is to be studied, not for the sake of any definite answers to its questions, since no definite answers can as a rule be known to be true, but rather for the sake of the questions themselves, because these questions enlarge our conception of what is possible, enrich our intellectual imagination, and diminish the dogmatic assurance which closes the mind against speculation. But above all because, through the greatness of the universe which philosophy contemplates, the mind also is rendered great, and becomes capable of that union with the universe which constitutes its highest good. Bibliographical note. The student who wishes to acquire an elementary knowledge of philosophy will find it both easier and more profitable to read some of the works of the great philosophers than to attempt to derive an all-round view from handbooks. The following are specially recommended. Plato. The Republic, especially books 6 and 7. Descartes. Meditations. Spinoza. Ethics. Leitnitz. The monadology. Berkeley. Three dialogues between Hylis and Philanoas. Hume. Inquiry concerning human understanding. Kant. Hologamina to any future metaphysic. End of chapter 15. This concludes the reading of The Problems of Philosophy by Bertrand Russell.