 Okay, apologies for the late start. I'll try and speak a little bit faster to compensate. Okay, so today we're looking at a Putnam on meaning and reference, and this general question Putnam has about whether your psychological states fix the references of your psychological terms. And what I want to bring out today is something about the way in which causal theories of reference bear on our knowledge of our own psychological states. So I want to begin with some remarks about what for most of us is probably the classical, the best known picture of your knowledge of your own mental states, Descartes, and then say something about how a causal picture of reference really blows up that kind of view of knowledge of your own mental states. So here Descartes, in the throes of his doubt, what shall I now say that I am? I mean, you can hear he's a bit excited at this point. What shall I now say that I am when I am supposing that there is some supremely powerful and, if it is permissible to say, malicious deceiver who is deliberately trying to trick me in every way he can? So the picture there is, you don't have any knowledge of the physical world at all. You don't have any knowledge of the world around you at all. It might all be a dream. It might all be a hallucination. You might have gone mad. There might be this deceiver getting at you. So what can you say about yourself? What kind of knowledge do you have of yourself in that situation? Do you have any knowledge of yourself in that situation? Well, I said can I now assert that I possess even the most insignificant of attributes which I have just said belong to the nature of a body. So you don't, I mean, and obviously you can't because if it's all a dream, if it's all a hallucination then your body is just as much part of that hallucination as anything else. But still he says in such a situation you still know that you exist and you still know therefore of some of your own characteristics. So which of your own characteristics do you have knowledge of in that situation? And here in this famous passage he says at last I have discovered it. Thought. Thought alone isn't separable from me. It might all be a dream. I might not know anything about what's going on out there but still I know about my own thoughts. I have some kind of special authority in my knowledge of my own mind. So if you think what's going on here you, it's being supposed that if you consider someone plunged in thought then they might not have certain knowledge of what is going on around them. But still when you look, when you survey your own mind you first of all know whether you're thinking and secondly you know what you're thinking. And that's a very intuitive, appealing idea. I might not know much about what's going on out there but still surely I can survey and know about what's going on in here. Now knowing whether you're thinking and knowing what you're thinking knowing whether you're thinking well if you don't know about what's going on out there then you don't know whether your thoughts refer, right? That's all right if I don't know whether Sally exists then I don't know whether my thoughts about Sally refer. So if I know whether I'm thinking in this situation the meaning doesn't depend on reference because my thought has significance whether or not there's any reference for it, right? That's all right? Because the reference is something out there, something physical the meaning, the thought is something you know about whether you're not, the physical is there. And if you know what you're thinking then presumably you know if you have a thought here now and you have a thought then then you know whether it's the same thought if you know which thoughts you're having then you must know whether it's the same thought you're having here's there, now is then. So knowing what, I mean that's all, it must come to at least that you know whether it's the same thought again but if you have a causal theory of reference if you have a causal theory as to what is giving content to the thoughts that you're having then that challenges that picture because on a causal theory of reference there's only the physical stuff out there that is giving significance to your thoughts so if that stuff is not there if you can't have meaning without reference and the causal theory seems to suggest that you can't have meaning without reference if there's no reference then there's no causal chain and nothing to give meaning to your thoughts then you don't actually have authoritative knowledge of whether you're even thinking there might not be anything out there to be giving your thought causal significance if you can't have meaning without reference as the causal theory suggests and if, as I've suggested a few times on a causal theory of reference you can't really tell infallibly whether it's the same thought you're having again or not because the sameness of thought requires the sameness of the object out there generating the thought and you can't know about that just by surveying some internal domain any more than you can know just by surveying the pixels in two photographs whether or not they are shots of one and the same thing so the causal theory of reference really seems to blow up that picture of the mind as an internal domain that you can survey without having any knowledge of the physical world around you and have authoritative knowledge of independently of your knowledge of the physical world okay? I'll elaborate that point I mean that's putting it very abstractly and schematic I'll try and give some examples in a moment but that's just a state schematically the general connection between the causal theory of reference and what picture you have of your knowledge of your own mind it really seems to blow up the Descartes classical picture I do think that's true okay? straightforward enough can you more so if this is Descartes yeah just doing that which is what Descartes is doing as good as I shot as you can see he's getting knowledge of more than his mind I see you might say that and in fact you'd have to say that if you're going to hold on to Descartes' line you couldn't really hold on to Descartes' line exactly because Descartes' line was I give up my knowledge of the physical world but I still have knowledge of what's going on in here you're saying I can get my knowledge of the physical world from my knowledge of what's going on in here that seems a little bit weird doesn't it if you're just sitting by the fire I mean Descartes could have thought I'm just sitting by the fire thinking about Sally but I couldn't be thinking about Sally on the causal theory of reference unless Sally existed so Sally must exist right? you were wondering if Sally was merely imaginary if she was just one of your constellation of imaginary friends and then you thought no I couldn't even have this thought on the causal theory of reference unless Sally existed so Sally must exist did you say metaphysical causation aha causation in itself yeah that's right the causation itself is what's required for knowledge but the causal theory of reference seems like a kind of a priori theory yeah I mean Descartes could just have read Kripke if you remain and said boy that's right the causal theory therefore given that I know that I'm thinking about water there must be such a stuff as water it can't all be a dream I'm just stating it I actually think that's an important view and I actually mean to discuss that line next time absolutely I think it's an important line of reasoning to pursue so I want to cut to another part of the forest for a second and look at what Putnam says about natural kinds and then look at how a Putnamian or Kripkean theory of names of natural kinds bears on these points about self-knowledge I also want to when I come to this section for you I want to suggest a slightly different way of reading Putnam to the way I had last time I think both these strands of thought are in Putnam's article so I will already set out one but I'll set out the other now okay what's a natural kind the idea of a natural kind is the idea of a distinction that's out there in the world independently of what anyone thinks so some classifications are projected onto the world by us out there in the real world there's just a whole bunch of atoms buzzing around and lots of the distinctions that we make between different kinds of collections of atoms are just projected by our own interests our own interests I mean the distinction between something that's interesting and something that's not interesting is presumably entirely relative to what your interests are it's a projection of your own interests onto the world out there yes that's okay but then you think well there are classifications of the world out there that don't depend on any of us in that way and really isn't what science is doing is trying to discover what distinctions that are in the world out there independent of any of us independent of you or me so the idea of a natural kind is the idea of a classification that's out there in the world independently of us and we're just trying to get on onto it I mean when scientists make major distinction things that have electrical charge and things that don't have electrical charge they weren't saying well we find this we project this onto the world they were saying that's out there and we are trying to find out about this distinction so for a distinction like that how you find out about it is one thing and what it is intrinsically is another it's not your interests that determine what the distinction is rather the distinction is out there and you're trying to get on to it so the general picture I suggested for natural kinds last time was you have a set of symptoms as with the disease you have a set of symptoms of being this kind of thing underlying structure something out there in the world independent of you that is producing those symptoms so I gave that example of gold in Archimedes where Archimedes takes it for granted that what it is for something to be gold is not a matter particularly of how it strikes anyone, how it looks it's a matter of having the structure that typically underlies that kind of behaviour you have a gold things exhibit solubility solubility in Aquaregia ductility malleability and so on all the stuff that gold does there's something out there that explains that we don't know what it is but we assume that there's some structure out there in the world and similarly for all the chemical substances and presumably for lots of names of substances and lots of names of animals so you usually think of the essence of a substance as a characteristic that explains the symptoms by which we usually detect the presence of the kind so there's that rough common sense folk notion of gold or of what it is to be a tiger but we don't take that as definitive we assume that something could have all those characteristics but not really be gold or not really be a tiger and even if we don't actually know what the essence is you can improve your use of the symptoms by which you test for its presence I mean Archimedes found a better test for the presence of gold if you're a physician looking for cases of Legionnaires disease you might not know what the virus is that produces Legionnaires disease but I think well maybe there's a presence of a particular hormone in the body that actually really indicates that you have Legionnaires disease you might think you can find better and subtler symptoms of having Legionnaires disease even though you don't know yet what the particular virus is so the poster child the paradigmatic example is chemistry in the periodic table so the periodic table is important because of the periodic law and the periodic law says the chemical properties of an element are a periodic function of its atomic number so what that's telling you what that seems to be telling you is if you want to know what the outward properties are of an element the way the thing behaves the way the thing behaves seems to be dictated by its atomic number so if it's exhibiting all these particular S1 to S4 then you say the atomic number is what drives that behavior that the element behaves the way it does so that seems to give you a very clear case of this kind of thing at work you can say with gold it looks like for all the properties that we're interested in of gold if you ask why does it have those characteristics why is it soluble in aquaregia then ultimately the answer is going to have something to do with it having the particular atomic number it does so that seems to give you a very clear case where here are all the substances and there are all the essences cleanly laid out in a structured table you can push it a little bit further and say that works for compounds too on earth what's playing that role is the H2O molecule that's what explains why water dissolved stuff has the boiling point and melting point that it does and so on on twin earth is XYZ that explains why the substance has those characteristics that's why we say it's a different substance on earth it's a little bit more complex when you start talking about biological kinds the names of animals if you take tiger and say suppose you have all the characteristics of being a tiger which are not really an expert but I assume that they include these ones right and you say well why is it that this thing exhibits these characteristics I guess the DNA structure has something to do with it but with biological species it's not nearly as clean cut as it is with chemistry there's no biological analog of the periodic table you don't get all the species nicely laid out in some great hierarchy like that and in fact DNA structure alone can't possibly be what does it because the notion of a species has a kind of historical component so that it has to do with members of the species all being sprung from the same stock all having the same kind of history having been generated tigers on Mars that exhibited this kind of structure had that very DNA they still wouldn't be tigers the best would be marching tigers they're not real tigers they have more species than earth tigers they have nothing to do with them evolutionarily so even in biology the case is a little bit more complex than it is in chemistry it's harder to know just how you'd pin down and say what the essence of a biological kind is it's not good enough just to, I mean DNA structure might vary between members of the same species and after all a species can split into two so a straightforward historical picture of what's going on with biological species doesn't sound very plausible either but on the other hand when you talk about a species like tiger or elephant or whatever then you're not just talking about whatever has these outward characteristics you're not just saying if it looks like a duck and quacks like a duck and all that then it is a duck that's really not true that's the point about that remark it's just false you could have something that looked for all the world like a duck but was just not a duck it didn't spring from the right stock it didn't have the right kind of biological material in it if it looks like a duck and quacks like a duck but it's actually made of metal and built in Taiwan then it is not a duck it's just a notion of a duck like that and similarly you could have a tiger that was not a tall ferocious or didn't have four feet didn't have claws wasn't straight we don't actually treat tiger or duck or these other notions as if they just have to do with the superficial characteristics that everybody knows about we talk as if tiger or duck are pointing you to some internal structure that we don't yet know about even though it's very difficult to say what it is and whatever you say exactly about the biological species they're very different to classifications like beautiful or well designed cool or gives me a strange ripply feeling if you take a classification like gives me a strange ripply feeling and ask well could there be a ringer for that could there be something that it strikes me just like something that gives me a strange ripply feeling I get all the ripply feelings alright but it doesn't really give me a strange ripply feeling that doesn't make any sense you see what I mean with classifications like that there isn't any hidden essence there isn't any underlying structure that's the thing you're really talking about you're not even trying to get at that you can't have something that really looks just like something beautiful is a dead ringer for something beautiful but it's not really beautiful how could that be it just doesn't make any sense so classifications like that aren't natural kinds, classifications like the names for biological species they don't have that nice tidy structure of the periodic table but in our ordinary thinking about biological species we're trying to get at something like that something out there independent of us psychiatric classifications are a really interesting difficult case here I take schizophrenia take the classification as someone schizophrenic or not schizophrenic is that a concept or it would be right to say if it looks like a duck and talks like a duck and so on and it isn't the symptoms of schizophrenia there's a usual list, things like delusions, hallucinations disorganized speech disorganized behaviour flattening of affect just not being very excited about anything, a kind of passivity well would it be right to say that that's what schizophrenia is that anything that exhibits those characteristics that's what we mean by a schizophrenic patient well actually nobody talks like that nobody thinks that you can define schizophrenia in terms of well nobody's a strong word most people don't think you can define schizophrenia just in terms of these explicit behavioural signs and say anything that exhibits them that's a schizophrenic and if you don't exhibit just those signs that you know are schizophrenic these are best guides to whether someone is a schizophrenic but on the other hand people have sometimes had the dream that when we know enough about the brain it will turn out that there's a set of brain structures like having brain disturbance 34 having brain disturbance 33 that will be a kind of periodic table of the psychiatric disorders where you can look at all these different brain disturbances and see them arrayed in a kind of periodic table of the things that can go wrong with your brain with these kinds of symptoms being seen as the consequences of that and that doesn't seem actually to be at all what is going to happen it's a very untidy picture of what is going on, what is different about the brain of someone with schizophrenia from a healthy patient, a healthy person and there just isn't going to be some nice structure there as you get with the periodic table that seems to be a fantasy so these are very difficult cases psychiatric disorders don't want to point to something beyond the outward symptoms and say but this is what it is really but in the other hand when you say well what is the underlying virus going to be what is the underlying structure going to be it doesn't seem right to say there's going to be any underlying any organized underlying structure there so the classification, the distinction between natural kinds and things that are not natural kinds there are lots of very difficult cases there chemistry in the periodic table is the clear case, the model that you wish everything else was like but everything else doesn't live up to the model but in the other hand there is certainly something right about that picture of a set of symptoms for which we want to find something distinctive underlying them one way to think of it is that if you've got a natural kind notion then it should be possible to make predictions I mean suppose you take that example that came up last time of mud can you know a bit about mud and you say well oh a mud I've encountered so far has been in Berkeley then could it possibly be right to do an induction and say well if we're all mud is in Berkeley I mean it doesn't make sense I mean the characteristic how should I say there's nothing deep about that's not quite what I mean there's nothing deep about mud I mean because of course there sometimes is but what I mean is being mud is just a matter of having certain superficial characteristics and you're not going to get any generalization about what's true of all mud beyond the position of these characteristics on the other hand if schizophrenia well let me take water as a clear case if you get a generalization about water like all the samples of water you've encountered boil or whatever it is 212 degrees Fahrenheit if all the samples you've encountered so far boil at that temperature then you can generalize and say all water will boil at that temperature you can't do that with mud if all the mud you've encountered so far did happen to boil at a particular temperature that might just be an accident mud is really a kind of heterogeneous classification for all different kinds of stuff that behave in the same kind of way part of the point of trying to classify psychiatric disorders is that if you can get them organized as natural kinds which is what people are trying to do basically if you're trying to get them organized not just so that there are classifications not just of the way things strike us but of the distinctions between patients that are out there in the world then you should be able to do inductions and say this treatment worked on this patient this treatment worked on this collection of patients therefore very likely this treatment will work on them all you want to be able to generalize from what goes on with a small sample to what's going to go on with all or at any rate the good majority of patients and if you know something about how the how the disorder came about in a particular bunch of patients you should be able to generalize and say well very likely this is how it comes about for all the most patients so one way to think of the importance of the classification is in terms of whether inductions possible whether you can generalize from a small sample to the behavior of the whole so this is an important distinction it seems to me but there's a lot of un-clarity in how you apply it in particular cases that's kind of my picture of what is going on to talk about a natural kind when Putnam was writing of course the subject was relatively new in recent philosophy and I think it's fair to say he takes it that chemistry is actually the general case that you get nice tidy essences for everything comfortable with that? you don't have to agree but you see what the idea is so I just want finally to say something about another way of reading Putnam the way of reading I gave last time I mean the way I get reading I gave last time is there in the text but there is another way of reading him and there is also in the text I think so we've got these natural kinds there are classifications out there in the world independently of us the substances, the species all those things are out there whatever we think of them so you could think on this way on the way of reading Putnam that I'm going to suggest now which is much more like Cookie's view you might say all names for substances are logically proper names a logically proper name was a name that didn't have any bits and pieces in it I mean unlike a description is not complex a name is simple you give meaning to a name just by saying I shall call this Bill I shall call this person Sally you give meaning to the name just by dubbing an object with that name so similarly you could think a name for a substance is simple by gold when you talk about gold you're just dubbing a substance you're just dubbing a kind when you talk about water you're just dubbing a kind so what's going on is that these names for chemical substances biological species any physical phenomena like electricity mass and what's going on is out there in the world there are these phenomena mass, electricity, tigers water I'll dub this one water I'll dub this one electricity I'll dub this one mass that thing out there is what you're causally responding to when you use the term so the terms the terms for natural kinds here are working just the same way Kripke thinks proper names work Kripke thinks when you get a proper name you've just got someone who's making you use that name you've got someone who's generating information about themselves radiating it out into the community and other people pick up on that and use that name to transmit the information that is being radiated out so similarly you could think that a kind is radiating information about itself out to you and what you do is you respond to that radiation of information by using a name to pick up the information and transmit it to other people so just as proper names represent in virtue of a causal relation to the subject words for natural kinds represent in virtue of a causal relation to the subject this is different to the account I was ascribing to Putnam last time the account I was giving to Putnam last time was a name like water is actually a description meaning the stuff that bears same L to the liquid around here that falls from the skies, fills the rivers and lakes and so on so that last week I was giving a reading of Putnam on which it's really water is really a description short for a description the liquid bears same L to the stuff which falls from the rivers and lakes and so on so that's a descriptive way of specifying the reference this is much simpler this is just saying you encounter the stuff you get into some rain you say I'll call that water and there isn't that explicit breakdown of it into anything complex so you could say I encounter the superficial symptoms of the underlying structure my encountering those superficial symptoms like it gets you wet, it quenches thirst and so on that is me being causally affected by the underlying structure so I exploit that when I use the name water someone on twin earth is exploiting the same symptoms but they're being caused to use the term by a different underlying structure that's why their term refers to something different so this really fits right in with the kind of progression from frege to cookie when you start out thinking well a sign you got a sense and a reference and the senses are going to be expressed by a description then you move with Russell to say well there's got to be a class of names that are more primitive than descriptions and then you move with Kripke to say well maybe ordinary names are primitive names, they're rigid and the reference is fixed by a causal chain so you could think that terms like water, tiger schizophrenia maybe they're like that too they're more primitive than any description and they're rigid and their references are all fixed by causal chains so names for natural kinds are going to be logically proper names on this picture and the striking thing here is that once you have this conception of what's going on with these names for natural kinds you're going to have problems with informativeness and signs that are meaning but don't refer because if what you've got is you've got to have the same causal chain in order to have the same sign well how can you know about that except by knowing an empirical fact about the world that you have to learn how can you know that the a priori that the same causal chain lies behind your two uses of a term and these points imply difficulties about your knowledge of your own mental states and the kind of difficulties that I began with for um... what was his name? D.C.A.R.T. D.C.A.R.T. D.C.A.R.T. D.C.A.R.T. D.C.A.R.T. D.C.A.R.T. I mean it's actually anticipating you remember we had the affecting story of spot D.C.A.R.T. in that situation if you're thinking here I am thinking about spot again dear old spot I was thinking about spot only yesterday well in that case which thing you're thinking about may have shifted though you didn't realise it yeah I mean that was the model of the story now which thing you're thinking about when you're thinking about spot has shifted though you didn't realise it then you can't know the same thought again just by doing the Rodin thing just by thinking but just by reflection surveying what's going on in your own mind because what's going on whether you're having the same thought again is not completely a matter of what's going on in your own mind it depends on what's out there in the physical world Isaac Bacheves Singer had a story I'm actually relying on memory for this but it's something like this about a man who sets out on a long journey from his village and it's going to take him weeks to get to his destination and every night outside his tent he leaves his clogs pointing in the direction in which he's going and after he's been on the road for some considerable time one night someone turns his clogs around and so he continues walking and after many more weeks he comes to a village and realises that the world is even stranger than he thought it was he says good god this looks just like my own village these horses look just like the horses from my own village this woman looks just like my wife it's unbelievable so there now suppose you ask him are these really horses he's perfectly with it his rights to say well they might be and they might not be he's thinking things in the very same way but he doesn't realise that he is for all he knows they might be different he can't tell just by reflecting on the contents of his own mind that he is thinking about the very same objects in the very same way when he's asked is that woman the same woman that you've thought about so often and he can't tell that it is just by reflecting on the contents of his own mind in his context he's actually perfectly reasonable for him to raise the question isn't that a different person I'm not thinking about someone different here so he's being presented with the very same people and things and substances in the very same ways he's thinking the very same thoughts but he doesn't realise that he is he doesn't have authoritative knowledge over the contents of his own mind so in these earth and twin earth cases okay this was Putnam's description and I said well if you were being swapped back and forth between earth and twin earth then you wouldn't even realise what was happening because it's so similar to this one but then you'd think you were having the same thoughts but you wouldn't be yeah and in the other hand it could happen to you that some year we may do this as a class exercise we take some individual and we say there really is a twin earth and we're actually going to fire you off there to see if what Putnam says is true kindly step into this box and carefully enough with enough stage setting yeah we might put you into the box and then three minutes later out you come into the same old classroom and say my god it's true it's just exactly like the classroom I just left everything looks just the same but of course you say they're not the same people it's not the same substance water here so I'm not thinking the same thoughts but you are thinking the same thoughts yeah so you might look at this scene and that scene you look at this scene before you step into the box you look out at the very same scene after you step out of the box and you say god you look almost exactly identical but I'm not having the same thoughts because this after all is H2O and this is XYZ Z you're wrong about that because they're both H2O but it's not a priori that you're wrong you can't tell that you're wrong just by doing the Rodin thing just by doing the Descartes thing so if you fall asleep by the fire and then you think well maybe it's all a dream but I can still know which thoughts I'm having it's not true and if there's no water out there for you to be causing you to think those thoughts then you're not actually having any thoughts at all ok, more of this on Wednesday, thank you see you then