 This is the lecture on International Monetary Systems. Oh, sorry, that was the other session. Well, this is actually, the topic is a philosophical one. You know, thinking about philosophy, sometimes I like the story about my friend, Father James Sadowski, gives his introductory classes. He says, the word philosophy comes from the Greek word philosophy, which means philosophy. I've always liked that one. You know, Father Sadowski is very good at somewhat unusual remarks. For example, there's his argument for free will, which is we wouldn't have the concept of free will unless we had it. And then I once gave that comment to Bob Nozick and Nozick said to me, maybe we wouldn't have the concept of bad arguments unless we had them. But what I wanna discuss today is some issues about method in economics. Some of this will be going over material you've heard in other lectures, but I think it's rather difficult stuff and it's always good to get the material from a slightly different angle. Now, Mises made, I think it's a very important claim, he thought that economics has a distinct contribution to make to epistemology. Epistemology is a study of how we know what is the nature of knowledge. And one of the topics in epistemology, and this was one that very much concerned the logical positivists who actually, they prefer to be called logical empiricists, was they were very interested in what's the nature of scientific knowledge in epistemology. We can cover much broader topics in scientific knowledge. We could say what is involved in any kind of knowledge at all. But the positivists were especially concerned with the nature of scientific knowledge. And Mises was, at least to this extent, like them, although certainly the positivists weren't the only epistemologists who were concerned with the nature of scientific knowledge. He was also very concerned with nature of scientific knowledge. And he thought that by neglecting economics, the positivists had made a big mistake. They'd failed to take full account of what was involved in scientific knowledge. They'd left out a branch of science that was very important that if they'd taken that into account, they wouldn't have come to the conclusions that they did. So in particular, he thought that in science, any kind of science aims at coming up with general laws. Say we have physics, of course, we have all sorts of general laws. Some sciences emphasize general laws as much such as biology. But in general, in science, the scientists try to come up with general laws, universal laws. But economics has a distinct way of reaching those laws that's different from the physical sciences. So he thought that the positivists had failed because they didn't take account of this special way that economists arrived at general laws. Now, the question comes up. Well, if economics has this special method of coming up with general laws, why is it that the positivists and other people interested in trying to come up with nature scientific knowledge? Why is it that they failed to come up with this? Certainly they're aware that they're such a discipline of economics. So when they're investigating the nature of science, why don't they ask what are the economists doing? And I should say, when I'm talking about economics here, when Mises was talking about economics, he didn't just mean Austrian economics. He meant it generally accepted price theory. At the time he was writing, he thought there'd been kind of general consensus among economists on price theory. Certainly this wouldn't apply to macroeconomics where you have all sorts of competing schools, but he thought at least the time he was writing, there was a large measure of agreement among economists on the nature of economics. So he said, well, why then did the positivists neglect that? And he thought that there was this kind of a psychological explanation or sociology of knowledge explanation for why economists, why people neglected what economists had to say. He thought that the conclusions of economics are counter to the ideologies of a lot of people, especially of the positivists. Because one of the things we learn from economics is if there are economic laws, these can limit what the economic policy can achieve. Supposing, say, if you, Mises has established that economic calculation under socialism is impossible in a large scale economy. So then if you like socialism, if you wanna put in socialist measure, then you're going to have a problem if economics has shown that this is impossible, or if you favor certain kinds of state intervention in the economy, and economics shows that these measure of intervention won't achieve the goals that you want, then, again, it's going to be very difficult for you to advocate these measures if you take economics seriously. So what Mises thought is that rather than accept the conclusions of economics and say, well, all right, we wanted to be socialist, but we can't now because economics has shown that socialism won't work. He thought that the socialist were suddenly, some socialists were so committed to their views that they would say we're just going to deny the status of economics as a science or ignore it. So he thought that that was one reason that the positivists who were a largely socialistic group were inclined to reject economics or not considering it when they were talking about the nature of science. And the main villain Mises had in writing, there was, sometimes we would have heroes and villains. One of his main villains was Otto Neurot. Well, I'll get to, I'll put him in, now I actually put him in the slides later, but I'll just mention him now. Neurot was a leading positivist. He had been a minister in the Bavarian socialist government in which was established for a short time in 1923, I think, then in 24 and then it was overthrown. So he was a very committed socialist. So Mises thought that a lot of the positivists were motivated by hatred of economics and its conclusions. That was why they ignored economics. Now, I've said that Mises thought that philosophies of science, epistemologists, should take account of the particular nature of economics. He thought that economics had a special way of coming up with laws. Now we can see what that is, say, if we can make a contrast between the physical sciences and economics. Now in the physical sciences, what is generally done is we say there's kind of a relationship between things, between events or things that applies universally. For example, just to take a simple example, we have Boyle's law of gases, which says other things being equal, the pressure and the volume of gas are a constant. If you multiply the pressure and the volume, you'll get a constant. So if that's true, then if the pressure increases on the gas, the volume will decrease. And if the pressure decreases, the volume will increase. Now, the way in which this operates, it's something just purely physical motions. It isn't that either the pressure or volume has some kind of mind and say, imagine the pressure is increased. So it isn't that the volume will be saying to itself, well, the pressure's increased. So I've got to contract to preserve Boyle's law. The volume doesn't have some kind of mind that it's putting Boyle's law into effect. It just, this law is just stating a certain physical relationship. But economic laws are different from this. In economics, people are not only physical bodies who are moving according to laws of physics, but they also act. They have conscious purposes and they act in accord with these purposes. They use means to achieve ends. And this is very different from the physical sciences where we can just observe physical, motions of physical bodies, we can just observe them externally. But as far as we know, they don't have minds, they're not acting. So in economics, we have a different way of coming up with laws from the physical sciences. I should say there are philosophers, there are people who've thought that physical bodies besides human beings or higher animals do have mental aspects. So there's some philosophies that you'll find in which the notion of physical bodies having some kind of mental aspect would make sense, but Mises rejected that idea. Now another thing I should mention where there is a view that Aristotle held and some of his followers, that the notion of purpose or teleology isn't confined to acting beings who can consciously pursue purposes. Aristotle thought there's a purpose in nature even though there's no conscious mind that's carrying out this purpose, but that's a view that you find. Many biologists are very attracted to that view although some aren't, but that's not a view Mises accepted. But whether he's right or wrong about that, he does seem clearly right that there is this special way of understanding human action, namely by talking about ends and purposes and means to achieve them, the category of action that's different from that used in the physical sciences. Now, when we're talking about action, there's nothing mysterious about this. We see action all the time. People are using means to achieve ends. We're all doing things. Say to use example, I want to drink a water so I have a means of getting that. I just take the bottle and drink it. I hope it's water in there. I can't handle anything stronger than if there's anything stronger in there, there's really going to be trouble. So let's hope for the best. So as I say, there's nothing mysterious about this. We do this all the time. We're always acting, we're aware of this. But in order to understand what's going on in an action, we have to use certain concepts, say in order to understand action, we have to have the concept of an end or a means. So these concepts, they're required in order to understand action. So if we're to understand action, we have to have these concepts. And in that sense, we can say, these are a priori concepts, meaning we have to have them before we can understand action if we don't have these concepts then action won't make sense to us. Imagine we didn't have the concept of an end or a means, then we wouldn't be able to understand what people are doing when they're acting. So a lot of people object to the notion of a priori concepts. But as I say, it isn't an unusual view, it's just saying that in order to understand something, we have to have certain concepts. If we don't have these concepts, we won't be able to understand it. Now, it's important, and I gave the example, say we could give an example, if you're learning a foreign language, you have to have certain concepts, you have to have learned certain concepts in order to speak the language. You won't say if you listen to people speaking the foreign language that you don't know, you won't be able to understand anything because you don't have these concepts. So when you talk about concepts being a priori, it's nothing more unusual than just saying you have to have these concepts in order to understand this particular kind of experience. Now, one confusion that a lot of people make when they think about a priori concepts, they'll say, well, then this means these concepts are innate, that people have to be born with them. You remember, you probably learned from history, philosophy, Descartes believed in innate ideas and we find this notion in the 21st century, Noam Chomsky, the famous linguist believes in innate ideas. Jerry Fodor is a proponent of innate ideas, but this is different from a priori concept. A priori just means to understand a particular type of experience, you have to have certain concepts. It isn't saying that the concepts have to be inborn in some way. I suppose maybe if you were talking about concepts without which you couldn't have any experience at all, maybe they would have to be innate, but in general, if you say just for a particular kind of experience, you have to have certain concepts before you can understand that type of experience, that doesn't involve any claim about innate ideas. Now, very important here also to realize, if you say that you can't understand a particular kind of experience without certain concepts, you say, well, you can't understand actions without having the concepts of ends and mean. This is a claim about the logic of action. It's saying that it's not possible to understand action without having these concepts. If you make a claim about some idea being innate, that's just a biological claim. That's just a claim about people's psychology, and it wouldn't be a logical claim. If we say, well, say we know certain things are priori, then if it was just say we had certain ideas or propositions just built into us biologically, we couldn't think otherwise in those, then we really wouldn't have good reason to believe those things. It would just be we'd been built to think that way. So that wouldn't give you good grounds for accepting those views at all. What we want in talking about the a priori is to come up with certain things that are logical conditions or a certain type of experience. So see, that's very different from, say, there's some kind of biological innate ideas. Now, when we apply this notion of a priori ideas to economics, this is the whole discipline that Mises calls praxeology. Now one thing's just a point of terminology should be where praxeology is the science of human action, this kind of discipline that Mises is talking about where we start with the action axiom and then try to elaborate what's involved in action, what deductively follows from it. But sometimes people use the term praxeology to mean the deductive method that is used in this study, but that's not really the way Mises uses the term. So praxeology is the science of action, not the method that you use in carrying out that science. Now, when you're doing this, it's important to avoid, again, another confusion. This is one that a lot of people, I'm gonna spend some time on this because a lot of people make this mistake. When we talk about a priori concepts, that's to say ones that you have to have in order to understand a certain realm of experience, people think, well, a priori concept, so this must mean these have to be mental. So somehow they're talking, if you talk about a priori, what's a priori science, an a priori science, it has to be talking about things that are in somebody's mind. You're really talking about something mental, but this is not the case, you're just saying you have to have certain concepts in order to understand a particular kind of experience, but praxeology isn't about what goes on in people's minds, it's about actions out there in the world, there are real actions going on. It isn't a discipline about how people think, it's about how people act. Now we could, here's where, example of where this confusion comes up. You remember, I'm sure those of you taking history philosophy, remember Descartes raised a famous problem, he said he was asking of all the various beliefs he has, which, if any of those, could he know to be certain that we're immune to doubt and he started doubting all his beliefs, he said, well perceptual beliefs are subject to doubt, he tried to say, is there any belief he had that wasn't subject to doubt, and of course he comes up with a famous one, but he can't doubt his own existence, and from that he tries then to build up other beliefs, he says, well then he proves the existence of God, and from that he gets the sense perception is reliable. So what Descartes is trying to do is to solve a skeptical problem, he's saying, can I, having shown that there's some certain belief and establish other beliefs about the world that are also things that we know, but this isn't Mises project at all, Mises is not doing epistemology in this sense, he's not trying to deal with a problem of skepticism, he's just as all scientists do, not just economists, scientists take for granted, I think rightly so, that the world exists, that other people exist, so Mises in starting with the action axiom is not talking about just something that's going on in his own mind and trying to deduce the existence of the world, this is just not his project, he's not trying to do that. So as I say, he's taking for granted that other people act that he acts, and he's trying to figure out what follows from that, what can we know about the nature of action, given the fact that everyone acts. Now sometimes I've had people ask me, well, how does Mises know that his conclusions apply to anything other than his own actions? Say he's reasoning, he's gotten various conclusions about action, say we know someone always chooses his highest value preference, well how does Mises know that this applies to anything other than his own action? And the answer to that is quite simple, we've already in essence given it, is that Mises is not talking about his own action, he's just talking about action, he's not describing his processes of thought, he's just asking what is involved in the concept of action, in the way we know it applies to others, it isn't referring to him in particular, and we can, the fact that these concepts enable us to make sense of other people acting is how we know it applies to them, it's not, he's not a solipsist, someone who just believes that only he exists, that only the categories of action apply only to him. There was a story about solipsism, that's the belief that only you exist, I remember that Alvin Plante tells, he said once he met someone who's a professor at I think a medical school who was a solipsist and he was talking to some students of this professor and they said, oh yes we're very careful about this professor because when he goes, everybody goes. Now, I now, having given some of the background of what means is meant by our priori concepts and practicality, I now wanna talk about the group that he considered his main methodological enemies in at least in the 1930s. There was also the German historical school, but they were larger from an earlier period that he considered enemies. Now, the positives were a group, here I'm going over some material that Hans Hoppe dealt with in his lectures, but as I say, I think it's always good to hear some of the things again, at least from a slightly different perspective. So the positives were a group centered around Moritz Schlick, who was a professor of philosophy at the University of Vienna, and I think they started around 1928 and they lasted throughout the 30s. They were disrupted when the Nazis invaded Austria in March 1938 and a lot of the members of the group then took positions in other countries. A lot of them came to the United States and as I say, Schlick was the head of the group, but there were other famous people in it, such as Otto Neurad, whom I mentioned earlier. Friedrich Weismann was in it, the Rudolph Karnapp. So this was the group that Mises was largely opposed to. Now, what the Postavists were very much concerned to oppose what they called metaphysics. Now, if you studied history of philosophy, you know there are some philosophers, especially past philosophers, who had the view that just by thinking about things, you could build up a picture of the world that showed the world to be very different from what it appears to be. Say, for example, Leibniz thought that the world consists of certain immaterial atoms, kind of mental atoms that he called monads, and each monad had been programmed with a completely determined way by God who was a supreme monad. So he thought all of this very unusual philosophy could just be established just by thinking about things. We could come up to this conclusion about the nature of the world just by thinking about things. It's very contrary to what you would expect just from studying the physical sciences from common sense observation. He wasn't the only philosopher who thought that. Say, we have Bishop Barkley thought he could show that matter doesn't exist. The world is composed entirely of ideas and acts of thinking. So the positivists were very much opposed to metaphysics. They thought these metaphysical statements weren't based on anything, and they, in their study of theorem knowledge, wanted to say that only knowledge that's based on either sense observation or certain rules of logic counts as real knowledge, is kind of speculative knowledge of metaphysics. Certain metaphysicists had proposed wasn't really acceptable. So what they said, one of their fundamental beliefs was that knowledge is really confined to what we can learn in science, and they'd also accept common sense observations about the world, but really science is the real model of knowledge. So Mises' response to that was, well, if you want to say that, he wasn't going to challenge that. He wasn't going to say, Mises didn't believe in metaphysics either, but he said, as I indicated before, well, you're not to the positivists, you're not taking account of the full nature of science because you're ignoring economics. Economics is a science, but economics precedes in this deductive fashion from these a priori concepts and the way the positivists pictured science was an empirical discipline dealt with generalizations about sensory observations. So economics wouldn't qualify. So what the positivist's response to Mises was that his style of economics doesn't, in fact, qualify as science because it fails the test of the verification principle Now, what was the verification principle? Well, this is a statement about, applies according to them about knowledge about the world and he claimed that we know something about the world. Suppose I say, for example, I know that I'm giving a lecture now, that would be a claim about something going on in the world, so it would have to meet the requirements of the verification principle. Now, there is two really forms of the verification principle, the stronger and the weaker one. The stronger form says that the meaning of an empirical statement is its method of verification. So not only is that saying that every empirical statement has to have some method by which you can verify it, it's saying that the meaning of a statement just is the way you verify it. But this strong form of verification principle doesn't seem very plausible at all. Suppose you say that, reading the historical statement, Caesar crossed the Rubicon River in 49 BC. Well, how would you verify that? Well, you could read various books that had made that claim that you accepted, various historical books, or you could look at various documents that were evidence for the claim that Caesar crossed the Rubicon River in that year. But it seems clear that that wouldn't be what the statement is saying. The statement Caesar crossed the Rubicon in 49 BC doesn't mean if you look in certain books you'll find the statement Caesar crossed the Rubicon in 49 BC. That just isn't what it means. As Bertrand Russell pointed out, in order to know what we would need to do to verify a claim, we have to know what the statement means first. How would you know that the way to verify Caesar crossed the Rubicon in 49 BC would be to look at certain documents unless you already understood what that statement means. So it seems like the strong form of the verification principle just wouldn't work. But then kind of a much, probably a better version would be the weaker form of verification, which would just say any empirical statement has to have certain sensory observations that can confirm it. If I say I'm giving a lecture in this room there have to be ways that could be confirmed. Say people could look and see or listen to me giving a lecture. So you'd be able to confirm that I'm giving a lecture. So at first sight at any rate this principle doesn't sound so bad. Just say if you're making a statement about the world there has to be some observation that can confirm it, that will be evidence for it otherwise it isn't passing this test. But if you say that then it seems that economics can meet the test of that principle because then suppose you say I always choose my highest value preference. Well, economics says that people always choose their highest value preference. Well, then you can just see whenever you choose something are you in fact choosing your highest value preference at the time you're choosing. Can't you verify the statement in that way? So it seems then that economics has passed the test even though it's working in this deductive way it's trying to come up with consequences of action but just deductively it isn't coming up with its conclusions experimentally as they do in the physical sciences but still seems that we can verify them that the positivists didn't accept that either. They said when Mises and the other praxeologists say an actor always chooses highest value preference then all that's being done is that the highest value preference is being defined as the one you actually choose. So according to them there's no empirical claim made it's just that Mises is proposing to define the highest value preference as the action that you choose but this doesn't seem right though does it? It isn't that Mises is defining the highest value preference as the one you choose on the contrary he's just making the claim that we know what a preference is he's saying at the time you're acting if you rank your preferences you're always going to choose the one you rank highest so it seems he's not making a definitional claim as the positivist thought. Now why what the positivists thought the reason they were reluctant completely reluctant to accept what Mises said is they held the view that you couldn't know anything about the world anything about the empirical world just by thinking about it they said you can't know anything just by reasoning a priori and I should at this point I didn't put it in the slides but I should just make a distinction we talked so far about a priori concept certain concepts that you have to have in order to understand a particular kind of experience but we can also this is a bit different we can also talk about a priori propositions a priori proposition is one that you can know to be true just by thinking about it suppose I say 2 plus 2 equals 4 well I can know that to be true just by thinking about it I don't have to keep counting pairs of objects and see if they add up to 4 I just know that to be true just by thinking about it but so what the positivists were saying was that a priori propositions don't give you any knowledge about what's actually going on in the world now just one thing I should say also about a priori propositions is that this is one where the positivists were wrong we shouldn't think that all a priori propositions or these kind of universally the propositions that are must always be true supposing I say let's take the one Descartes I suppose I say I know that I now exist now that's one that unfortunately for me won't always be true I'm not there is going to be a time when I don't exist so that's an a priori proposition it's one I know to be true just by thinking about it but it's not this kind of universal proposition must be true always so you have to be careful to distinguish a priori proposition from a necessary proposition one that always is true couldn't be otherwise so a priori just means you can know it's true just by thinking about it and just one further point while I'm on the subject there are some a priori propositions that if you deny them you'll be involved in what's called a performative contradiction for example suppose I said I don't exist I wouldn't be able to say that unless I did exist so my saying I don't exist presupposes that I do exist but it's important to realize that not all a priori propositions have this feature sometimes I've heard people say well it's a test of a criterion for an a priori proposition that if you're denying it presupposes that the proposition is true and that isn't right supposing I say 2 plus 2 equals 5 my saying that doesn't presuppose that 2 plus 2 equals 4 2 plus 2 equals 5 is a contradiction but my saying that does not presuppose the true a priori statement that 2 plus 2 equals 4 so why did the positivists think that these a priori statements couldn't give you any knowledge about the empirical world but they thought that all a priori truths were really tautologies which really the tautology is really something like a definition or part of a definition or a law of logic so they thought a priori statements are just tautologies they're not really telling you anything new about the world they're just really conventions that are explaining how you propose to use certain terms so I've gone over this already they said in response to Mises that if you say you always choose your most highly valued and all you're doing is saying this is how I'm going to define most highly valued and is the one you choose so if that's right and I don't think it is but if that's right you wouldn't be learning anything about the world in saying you always choose your most highly valued preference you would just be saying that's how you're defining the terms so the basic claim positivists are making is I say is that the a priori judgments are simply tautologies there's an exact famous example that Wittgenstein gives someone asks you what the weather is in a certain place and you say well it's either raining or it's not raining what you've said is perfectly true it's just a law of logic it's either raining or not raining but it doesn't tell you anything about the weather you're not learning anything about the world so what the positivists thought were a priori statements were either tautologies of that kind or simply that would be an example of law of logic or the other kind of tautology would be a definition and it seems clear just by defining terms in a certain way you can't show that something exists if you just say well I'm just going to be using terms in a certain way that doesn't show that anything exists you can't just make something true just by definition so this was the basic way the positivists tried to argue against Mises' praxeology said it's a priori so it's just either it's tautologies it's not telling you anything about the world now what Mises responded to this he had several responses and he said well it seems like even if you accepted what the positivists were saying economics does tell you new information about the world say if you look at the conclusions of praxeology say law of marginal utility it's not at any rate obvious to people that this law is true it's something you have to reason out so aren't you learning something about the world even if it is a tautology in the positive sense you're certainly learning something new even if it doesn't qualify by the positivist standards there's knowledge about the world now it's interesting the positivists themselves admitted this they admitted that people could be surprised by mathematical theorems even though they thought that mathematics consists of tautologies so when they said you're not getting information by just reasoning with a priori statements they would have admitted people can get information in the sense that they learned things they didn't know before but what they deny was that what this information is giving you is knowledge about the world they said what you're just learning is just the implications of using certain terms but Mises had I think a good objection to that view that view said well maybe we're learning something new but it's not something new about the world he said well certainly doesn't mathematics how is it that mathematics is so useful how is it that mathematics applies to the world it's just a set of conventions and how is it doesn't mathematics really about what takes place in the world otherwise why would we be so successful in using mathematics it would seem odd just by defining terms in a certain way and coming up with their implications that this would enable us to do all sorts of things in the world it would seem like there is a big problem for the posthumous view at least as applied to mathematics now I want to raise in the time left a few further problems for the posthumous view one was and I covered this a little before when I was talking about a priori concept of the experience is Mises concept of the a priori is local in the sense that you say we have to have certain concepts that before we can understand action but that's quite compatible with thinking that these concepts are empirical in the sense that they're somehow derived from experience it's just that we have to have these concepts before we can understand this kind of experience so that really there isn't there need not be a conflict between a priori concepts in Mises sense and verification principle now another problem is kind of a famous one for the verification principle this is one that Hans Hoppe covered in his Sunday night lecture is that the principle appears to be self-refuting in that it says that all meaningful statements have to be either analytic analytic statement is just a tautology just a way of saying principle logic or a way of defining terms part of the definition so all meaningful statements are either analytic or empirical but that statement doesn't appear to be either one it doesn't appear to be analytic or it's not empirical either now there are various ways the logical empiricists tried to counter that probably examples were one they said was well if you investigate meaningful statements you'll find that they fall into one of these two categories so they could say that that is an empirical claim it's just you take meaningful statements and you'll find they're either tautologies or empirical claims but the problem with that is if they say that then they're excluding from consideration metaphysical statements how do we know metaphysics is meaningless well we can't say just because metaphysical statements violate the verification principle and then claim it's an empirical claim that the verification principle is true because we rather cook the data we haven't put in the metaphysical statements in the first place so it's rather begging the question then if this is another line the positivist said the statement, the verification principle is analytic because it's a proposal about how a meaningful statement is to be defined then why should people say who like metaphysics who think it's meaningful except that claim it would just seem to be something that would need to be argued for rather than just asserted as a criterion now another problem is that let's just take the principle the way the positivist wanted it so they wanted really that all scientific statements would come out meaningful and metaphysical statements would be excluded but they were never able to state the criterion in such a way that they could get just the statements they want in the ones they didn't want out as it happened any time they kept coming up with more and more elaborate version of the principle there was a great logician at Princeton who was later taught at UCLA I remember seeing him in his later years named Alonzo Church and whatever anyone would come up with a new version of the verification principle he would come up with some new counter example to it and destroy it he would come up with a version of the verification principle that really passed scrutiny Alonzo Church was a very interesting person when he would lecture he was extremely precise when he would write on the blackboard when he would come into the class he would spend about ten minutes erasing the blackboard to make sure there was nothing no specs of chalk that might interfere with any formulas he wanted to put on the board so one way people could upset him was to also would be to say, I think you made a mistake in something you put in he would get very panicky and then look at the thing for quite a few minutes but anyway he was the one who really thought about the verification principle that doesn't show nobody would be able to come up with a version that did what they wanted but no one in fact has done that now another problem is it's not clear what is supposed to be the argument for the view that we can't know anything new about the empirical world just by thinking about it why should we think that all you can do just by thinking about things is just to come up with definitions or conventions why can't we know something about the world just by thinking about it I think at the heart of the positivist view this I'll get to a bit later the positivist view why they thought that is that they said well if you think about something then what you're going to come up with is some kind of necessary truth something that must be the case in any possible circumstance in say say in any possible world but all empirical knowledge is contingent that's to say both I say I'm giving a lecture now that's an empirical statement it could have been otherwise I might not have been giving this lecture I'm sure you all wish I hadn't been giving it but so they thought the positivist thought well any statement gives you knowledge about the world is one that could have been otherwise but they say a priori statements are ones that give you just necessary propositions give an example of statements that are a priori and contingent but I think here we can challenge the positivist why should it be why should we think that all propositions about the tell you knowledge give you knowledge about the world are contingent in this way why can't there be necessary truths about the world that we haven't given any reason to think that now the last thing I'll mention is one of the greatest 20th century philosophers W.B.O. Quine challenged the whole idea of the a priori also rejected distinction between analytic and synthetic propositions what he said was our beliefs confront the world as a whole we shouldn't think say you have a separate beliefs you say well this belief is a priori I get this belief just by thinking about he thought all our beliefs are interconnected in such a way that none of them are ones that could never under any circumstances be given up even laws of logic could conceivably be given up is just some say something say I have a belief set I believe I'm lecturing now but something and then I can come up with observations that will support that but there it isn't a straightforward matter having a belief and then having observations these observations are tied to other beliefs my belief I'm giving a lecture is tied to still other beliefs so what's happening as new sensory data comes in is that I'm adjusting the whole framework some way to cope with the new data so he thought that nothing is immune to this kind of revision even laws of logic but he had to modify that some of his later work he kind of retreated a bit on that and I think it's not really a plausible position to think that the laws of logic at any rate are subject to revision so I have a few minutes left so we can have any questions objections yet so when I when I get into arguments with people into a debate about Karl Hopper's being a circle I know Hopper made the concession that well there might be some role for a pre-are knowledge in formulating hypotheses and ordering our understanding I have an intuition that much surely means something for Meesey's claim that praxeology is a valid kind of science and I wonder oh yeah I just see you have a t-shirt that says I'm not dead yet that's very good well I suppose if you're able to put it on it's true so well you see I think that's right see what Popper didn't think just as you say that you could come up with a priori conjectures we see he had what I think is a kind of an odd view that he encounters more than a conjecture because he thought well supposing you what he would say is supposing I say something well I know that I'm acting so he says well how can you say that's a conjecture don't you seem like you really know that so he says well look there have been cases before where people were quite certain things but they turned out to be wrong about them for example I suppose you have the notion of a class membership it seems certainly to make sense to ask the question it certainly seems to make sense you could have a class of all classes that are not members is not a member of itself but also show that's contradictory so the claim would be any a priori claim you make could be refuted later because maybe you made some mistake about it and as I mentioned in one of my previous lectures I think this is a fallacious view it doesn't follow just from the fact that I've made mistakes that in I think that's really this notion of everything is conjectural is why he just wanted to confine the a priori to this kind of limited role of proposing hypothesis I should say he just came out a few years ago of his correspondence he had an extremely high opinion of Mises he refers to him as a great man he mentions he met with Mises a number of times he said in the 1930s and began he says Mises was very suspicious of him he thought he was in a rationalist and a dangerous person and as usual Mises was right well let me see I think we have time for about one more well I don't think that you could I mean that would just depend on what that would be an empirical claim about the person certainly Mises never claimed to be able to do that well all right thanks very much