 So today, we're doing Churchland's Eliminative Materialism of the Propositional Attitudes. And on Thursday, we'll be doing Dennett's True Believers, The Intentional Strategy, and Why It Works. Dennett's paper is a very brilliant paper. Dennett is a very variable performer, it seems to me. But this paper is him absolutely at the top of his game. This is a marvelous paper. Churchland's theory about the mind is very simple and very radical. The theory is there is no such thing. The problems we've been discussing all term are, in general, fake problems. Because the mind simply does not exist. Now, I think when you first encounter that idea, it seems that, well, this has got to be wrong, right? Nobody says, well, that's what I've always thought. The mind doesn't exist. I'm not conscious. I don't think. When Descartes said that the first and most immediate certainty is that I think, then I guess all of us in the class take it for granted. That kind of makes sense. That's a good starting point. The physical world might not exist. That is kind of uncertain. But whether I exist, whether there is thinking going on, that is certain. But Churchland's move is to turn that right around the other way. So the first thing to do is to see how Churchland's idea is even intelligible. How could that possibly be right? So I want to spend a little time talking about the idea that our ordinary thinking about the mind is a theory. Talking about the mind is a theory in the way that talking about the physics of the objects around you or the behavior of electrical circuits, that involves theory. This is really the decisive move in what Churchland is saying. If folk psychology is a theory about the causes of behavior, if when you're talking about what you think, and what you feel, and what you believe, you are working with a hypothesis about the causes of your behavior, then that's something that, in principle, could be completely wrong. So if Churchland can be persuasive about this, then he's really halfway there. This is really the decisive move to stop it seeming just unintelligible that the mind might not exist, to having it seem like a reasonable hypothesis where it might go one way and it might go the other. So look, here's a puzzle. Here's a puzzle. Here is Maxi. Here we have Maxi on the left. Maxi? OK. Now, as you can see, Maxi has a ball. Yes? OK. Now, what's going to happen is Maxi puts his ball in the red box. Follow me like a leopard, OK? You're completely with me so far, OK? Now Maxi leaves the scene having put his ball in the red box. And now Maxi's dad, who, as you can see, is a somewhat furtive and suspicious-looking figure, comes onto the scene. And Maxi's dad moves the ball from the red box to the blue box. So Maxi doesn't see his dad move the ball. Maxi doesn't know that the ball is in the blue box now. OK, following me like a leopard. So here is the crux. The big moment is when Maxi returns. Maxi wants his ball. Where will Maxi look first? OK, put your hand up if you think the answer is the red box. Very good. Put your hand up if you think the answer is the blue box. Wow, OK. Very good. The right answer is the red box. Now, so congratulations. But the thing is, for each of you in this class, there was a time when you could not do that, when that problem would have been impossible for you. This kind of scenario has been shown to children between two and five years old, thousands and thousands of times since the early 90s. And actually, some of the basic work on it having been done right here in Berkeley, in Ellison Gopnik's lab. And the basic finding was children at three years old will say the blue box. Maxi will look in the blue box. They don't have the idea that Maxi's going to look in the red box. It's a very robust, it's kind of a surprising finding. And it's a very robust one. Children at three years old will say the blue box, and you can't get it out of their head that it's going to be the blue box. By the time they're four to five years old, children have got it. So you'll be pleased to hear that you did at least as well as the four to five year olds. But that is a big hurdle. So what is going on there? Why is it that children can't get it? It seems like the most obvious thing in the world. So what could be going on for children when they're at a level where they understand this perfectly well, but they don't have the concept that Maxi might have a false belief about where the ball is. They just don't have the idea of false belief. It's been tested from many, many different directions this finding. For example, also about children's knowledge of their own beliefs, one classic test. You show a children a candy box, and you say, what's inside the box? And the child says, candy. Then you open the box, and you show the child it's full of pencils. And the children will be really surprised by this. You picture it right? And someone said to me, their jaws literally drop when they see the pencils. That was the last thing they expected. And then you ask them a couple of minutes later, what did you think was in the box when I first showed you it? And they say, pencils. They don't have the idea that they themselves could ever have had a false belief. So what seems to be going on is that there's an early concept of belief that is not really capable of being false. Belief at this early stage is a relation between the person and a bit of the world. So if you're asking, what's the bit of the world that is going to guide Maxie in looking for the ball? The only ball involving bit of the world is the blue box. So the three-year-old is going to say, well, Maxie, if he's got any knowledge of any beliefs at all about where the ball is, they must be those that involve the place the ball actually is. Therefore, he's going to look there. Something like that, that isn't the notion of belief as something that's capable of being false. Belief is a relation between the person and a fact out there. So what's going on seems to be like, it seems to be some ways parallel to development of the concept of electron, that there's an early stage in which scientists are thinking about electrons, and they have hypotheses as to what kind of experimental findings they're going to get using this model of the electron. And then the findings come out wrong. They don't get the findings they predict. So they go back and they say, we need to think about electrons completely differently. Or we need to introduce the concept of another kind of particle as well. It's theory formation here that you're getting from one level of theory to another. So what happens later is that what happens in the transition from 3-year-old to 5-year-old is that at this early stage, the child has got all these predictions using this primitive concept of belief as a relation to an external fact. And you can see that what's going to go wrong here, the child's predictions are all going to come out wrong. Because does Maxie look in the blue box? No, Maxie looks in the red box. And the child, the 3-year-old, has absolutely no way of explaining why Maxie is looking in the red box. So the child is saying, well, I need some new concept here. I need some new construct to explain why Maxie is looking in the red box. They pick the blue box. They don't pick the red box. Well, because they're taking it that the only cognitive relation has, Maxie has a view as to where the ball is. They know the ball is in the blue box. So yeah, remember, you were told, as what I say, follow me like a leopard. That was you saw dad do that, unlike Maxie. So you knew the ball was in the blue box. I mean, if you're the child in the experiment, yeah. That's why you're making that prediction. He's going to look in there. But all the predictions are coming out wrong in what the child is doing at 3-years-old. So the child needs a new theoretical construct. The concept of a belief as an attitude to a proposition that might be true or false. So what the child develops is the idea that there's that proposition. The ball is in the red box. And the child can believe that. I mean, Maxie can be believing that whether or not it's true or false. Is that OK so far? Let me just, the developmental psychology through the 1990s basically consisted. Well, someone once said to me is the subject divides into those that are working on false belief and those that are not working on false belief, with those that are working on false belief being vastly outnumbering everyone else. So let me just go over that idea of an attitude to a proposition. Because Churchland talks such a lot about this. What's a proposition? Class, a proposition is something that can be capable of being true or false. So the bag is on the table. Is that a proposition? Help, is that a proposition? OK, very good. OK, so if you've got a proposition, something that's capable of being true or false, the kind of thing that's expressed by a sentence, you might say a thought, something like that. So for example, if you take here are two thoughts, here are two people thinking, Jim thinks that the University of California was founded in 1873. Sally thinks that the University of California was founded in 1868. So are there propositions that Jim and Sally have attitudes to? Yes, there they are. The University of California was founded in 1873. The University of California was founded in 1868. So these are two different propositions, but Jim has the same attitude to his proposition that Sally has to hers. Jim believes that, Sally believes that. These are attitudes to propositions. Yeah? So when you're thinking about the psychology of a person, a lot of what's going on is you have these attitudes to various propositions that the person has. You can think that practically anything. Yeah? What other attitudes are there to propositions than thinks there's hopes? You could hope that the University of California was founded in 1868. You could fear that the University of California was founded in 1868. Anything else? Other attitudes to propositions? Believes. Believes, yes? You can want. Want that, yes. You can want that, the University of California I mean, yeah. Is that it? Is that all a profit? Hey, come on. There are plenty more propositional attitudes. Yeah, I'm angry that the University of California was founded in 1868. Sure. Or if you take it a bit more, let's take something a bit more effectively possible. Like, he is here. I am angry that he is here. I wish that he were here. Would that he were here? I long that he be here, yeah? I dread that he be here, yes? Very good, yeah, I remember that he was here, yeah. I predict that he'll be here. I expect that he'll be here. You can do this. Very good, I see that he is here, yeah, perfect. I love that he is here, yes, of course, yeah, yeah. OK, well those are two particularly good ones they'll have to do, I guess. We'll settle for quality over quantity. OK, the general idea of a propositional attitude is fairly clear, yes? So far in the class when we were talking about consciousness, a lot of the time we've been talking about qualia, things like the sensation of redness or what it feels like when you have an Indian burn or the thrill of being in a fight, the ecstasy of a drunken brawl at midnight. And these are different to propositional attitudes, right? They don't have that same kind of structure, just having an itch or a pang doesn't have the same kind of structure. Now the intriguing thing about propositional attitudes is that when you look at those propositions, there are logical relations between propositions. And the attitudes cause one another in a way that mirrors the way that the propositions logically imply one another. OK, OK, this is a little bit subtle. Come with me down this track. Suppose that someone believes that either P or Q, right? Either he's here or he's in the cafe. Suppose he believes that he's not here. That proposition, either he's here or he's in the cafe and he's not here, do those propositions logically imply anything? Yes, what do they imply? He's in the cafe. Yes, OK. Yeah, X has that belief. I mean, how X came by that belief is another part of the story, right? God told X. OK? It's my story, right? So he believes that he's either here or in the cafe. He believes that he's not here. So these logically imply that he's in the cafe, right? So if X has these two beliefs, what will they cause X to believe? That he's in the cafe. Yeah? So there are the, if you just look at the propositions, there are logical connections between them. And then when you pan back and look at the propositional attitudes, there are causal connections between them. And the causal connections between the attitudes mirror the logical connections among the propositions. Yeah? If the subjects are all rational. If you believe two things that logically imply a third thing, then if you're rational and if you care, you'll believe that third thing. That will cause you to believe the third thing. If P is something that will cause anyone to be afraid of it, that doesn't quite make sense. P is a proposition, remember. That the tiger is on the prowl, for example. If P is a thing that anyone would be afraid of, but remember, P is a proposition. Yeah? You can be frightened that the tiger is on the prowl because you're frightened of the tiger. But the tiger is a thing out there with foreign claws. Yeah? Do propositions have foreign claws? No. So what you're frightened of has foreign claws. Therefore, it's not a proposition. This is a little bit subtle, right? You're frightened that the tiger is on the prowl. But what you're frightened of is not the proposition. What you're frightened of is the thing, the tiger. Yeah? So you write that there is causation here. That the object might cause you to be afraid. But that's different to this kind of pure structure here, which is that the attitudes are causing one another. You believe, say I'm afraid that the tiger is on the prowl and I believe that the tiger is on the prowl. I am afraid whenever the tiger is on the prowl and I believe that the tiger is on the prowl. Those two attitudes might cause me to have a third attitude, namely fear that the tiger is on the prowl. Yeah? Yes? That's right. OK, good, yeah. So that's to say, I mean what I said was when you're moving from believing that Maxie's got to be looking in the blue box to having the idea that Maxie's got beliefs that might be false, all you're doing is you're working your way into this theory where the way that the causal structure of a person goes mirrors the way the logical relations among the propositions go. So you're going to stack up propositions that imply a conclusion. Then anyone who's rational and cares, who believes all those propositions, will believe the conclusion. Yeah? That's all right? So this is a theory. This is a theory, the notion of an electron is part of a theory. You can think of the way the propositions are working here or as analogous to the way that numbers work in physics. And suppose you've got a gas, suppose you've got a right in front of you gas in a container, then you've got here a physical object, the gas in this container. And it's got various aspects, right? It's got pressure, temperature, volume, mass. So the way you describe the object, the way you describe the pressure, temperature, and mass and all that, is by giving numbers to them. Yes? Every individual step here should be perfectly obvious, but we are heading inexorably to the conclusion that the mind does not exist. So bear that in mind, right? So what's going on with a gas is that you know the law is governing the gas. So then when you give numbers to all these different aspects of the gas, you know how the gas is going to behave. So there are laws governing physical objects stated in terms of the relations between these numbers. So I'm told that if you've got a fixed, massive gas, a fixed number of molecules of the gas, if the gas pressure is P and the volume is V and the temperature is T, then the temperature is a volume times the pressure, right? OK. Thank you. I hope that's right. OK. So that tells you, once you know the numbers for the temperature and volume of the gas, now you know how the gas is going to behave because you know these general laws. So the way it works with people, suppose that you have been sitting next to the same person all semester, but you don't know much about them. You want to find out about them the way you might try to find out about a gas in a container in front of you. If it was a gas in a container in front of you, you give numbers to all the relevant magnitudes. With people, I mean you can give numbers to various of their magnitudes, their size and weight and so on, but that doesn't tell you about their mind. What you want to know if you want to know about this person as a person is there are these different aspects of them just as with a gas, there is pressure and temperature and mass. With a person, there are these different attitudes, hopes, fears, beliefs, memories, and do you give numbers to them? No. What do you do? Suppose you say, what do you hope of the person next to you? What are you hopes? Well, the kind of thing you would get if you ask, what do you hope is a whole bunch of stuff like I hope I get a good grade, I hope my mother recovers, I hope I get a vacation in Rome, I get elected to Congress, I pay my debts, this cough isn't TB, there's world peace, right? That's how you calibrate a person. You don't give numbers here, you give propositions for the attitude, hope that. You see what I mean? You're a big long list of what they hope, you're a big long list of, let's say, what they believe, you're a big long list of propositions that they fear or true, or what they love or true. Once you've done that, then you know how they're going to behave, because you know the analogue of the gas law, which is that the way that people behave will mirror the logical relations among the propositions. You measure people psychologically using propositions in the same way you measure physical objects using numbers. That's what's going on when we're talking about the mind. You've got a kind of abacus here, a way of explaining and predicting the behaviour of people, just as in physics, you've got a way of explaining and predicting the behaviour of a gas using numbers. You've got a way of explaining and predicting the behaviour of people using propositions. That's what you did between three and five. You catapulted yourself into using this theory that now seems so simple, and you just take it for granted. You don't even think about it. I hope that when I'm articulating this, it seems like I'm laboring something perfectly obvious, because I'm suggesting it's something you've been taking for granted in your own thinking since you were five. When you were three, it was a big struggle to get to that. But now working with this theory is a simple, familiar fact of everyday life. So there are laws governing people, just as there are laws governing gases connecting pressure, temperature and volume. There are laws governing people that are stated in terms of the propositions towards which the people have attitudes. So just a simple example of a law like that. Suppose that you've got two propositions, P and Q, and X believes either P or Q, and that X believes that not P. Then what will that cause to happen? It'll believe a Q. It won't cause Q itself to be so. Just watch it, that's all. For any person and any propositions P and Q, suppose that you want to annoy the neighbors, and you believe that banging on the wall will annoy your neighbors. Just to take an example of a random. Then you'll want to bring it about and you bang the wall. Generally. If you want to annoy the neighbors. On the other hand, if you want to keep peace with the neighbors and you believe that turning down the volume will bring about peace with the neighbors, then you will want to turn down the volume. Take a more respectable example. Very good. This is a little bit simple. You would really need some clause here, like, and you don't have any other relevant beliefs or desires. Or some way of looking, panning back and looking at the big picture. There's not going to be trivial to properly articulate all this. That's just right and important, what you say. But that we work with generalization is like this the whole time. That's how ordinary life is possible. As we were talking right now, I have a whole bunch of assumptions about what you believe and want. You have assumptions about what I believe and want. That's how you predict what people are going to do. If you're driving, you just assume that, well, if you're signaling left, that means you want to turn left and that means you're going to do this. You're assuming that the other person is broadly rational the whole time. So what's going on here is that when you were five years old, you worked your way into this theory from then until now, you've just got better and better at working with this theory. That's what folk psychology is. It's a theory about the causes of behavior. And since it's a theory about the causes of behavior, it could be completely wrong. If we've reached this point, if that seems plain enough so far, then you are already in a position where it makes perfect sense to suggest you might not be thinking, you might not be conscious, that might not be the right way to think. Okay? Yes? Folk psychology is working with... At this point, I can just talk about propositional attitudes and you know what I mean? Believing, desiring, hoping, feeling. Folk psychology, for present purposes, is working with all this talk about propositional attitudes in a way that explains and predicts the behavior of other people. Yeah? I mean, it's pretty good. We use it the whole time and it does us some good. We do a lot better. The five-year-olds are doing a lot better in explaining and predicting than the three-year-olds are. But what we'll come to in a moment is that there are big limitations in this. Yeah? Oh, no, it's okay. Okay, it's gone away. Okay, plenty enough. Okay, well, here's an analog for the way Churchland is thinking about our ordinary talk about the mind. I mean, after all, in our ordinary talk about physical objects, when you're born, you have a kind of physics of the world around you and you take it for granted that the chairs will support your weight, that heavier things will... I don't know, when you throw things, it's a very intuitive notion. If you throw... I mean, tempting though it is, I wouldn't actually do it. Well, if you just throw something around a little bit, yeah? Why does the thing move? Why does the thing move, continue moving, after it's left your hand? You might say, well, I can see well enough why it moves, while I'm holding it with my hand and I move my hand, but why should it keep moving? Well, a very natural theory there is that you communicate some impetus to the object. And the impetus is what keeps the thing moving, but impetus naturally decays after a while and then the thing stops moving. Yeah? We talk like that the whole time anyway. We often use it as a metaphor. The whole civil rights movement was given impetus by this speech. It was given some of this thing that kept it moving forward for a little bit, but then it naturally decayed. That was, in medieval times, the main theory, the main official... Did you hear that? Thank you. Okay. Okay. In medieval times, the explicit physics that scholars had was a theory stated in terms of impetus. So, why you have someone like this guy in his underwear here whittling something around, then why does the thing keep moving the way it does when you let's go of it? Well, it's because you gave some impetus to it and it was thought that impetus was maybe circular, typically circular, so that if you're doing that you'd give a circular impetus to the thing so it would keep kind of looping around. Is that theory correct or not? Yeah, it's not correct, but there are plenty of tests actually with college students where people are given puzzles like this and say, how will the thing move? If you had a gun with a spiral barrel that fired bullets through the spiral barrel, how would the bullets move when they came out? Straight ahead. Straight ahead is the right answer, but you will find a surprisingly large number of college students who think, no, it kind of goes right. It keeps whittling around. And that's a very intuitive answer. It's not like you say, well, it's just some kind of madness. You're born with that kind of physics. Nature gives you some kind of and it seems to have these notions like impetus in it. But in bitters theory just has a lot of limitations. There are lots of basic phenomena that can't explain. Like, why do the planets keep going? I mean, Newton seems to have had some picture like when the planets were first formed God kind of gave them up to get them going. But in impetus theory the impetus that the planets had to start with should keep running out so they should need to keep getting some more nudging to keep them moving, right? But they clearly don't need any kind of pushes like that. Or the tides. Part of what is so poignant about the tides is the way they just keep rolling in and out relentlessly in and out. The way they did it before you were born the way they'll be doing it after you're dead. And they don't need any push to do that, right? There is not impetus that is keeping the water moving. Or what Galileo basically did through decades of his life measuring the movement of balls rolling down inclined planes. Impetus theory couldn't explain the details of the varying speeds at which balls get down inclined planes. So what happened was that the notion of impetus got thrown out. Impetus theory got replaced in Newton's time by a more general theory that could explain everything that impetus theory could explain and also could explain all the phenomena that impetus theory just couldn't address at all like the tides and so on. So what happened was that the talk about impetus just got thrown out and no physicist nowadays talks about impetus. That's just not part of physics. There is no such thing as impetus. There is no such thing as that thing that you communicate to the object when you throw it. All you there are are force, mass, acceleration, friction things like that. Well it's replaced by notions like inertia. Inertia is something that everything has anyway. Impetus was something that you gave to the object. These are analogies. These are okay analogies. So the question is nature gives you, evolution gives you your folk psychology. It's very important that you be wired up when you're born with some way of negotiating other people. The most basic thing a baby has to do is to connect with the adults around it. That's the first thing right children can't make it on their own. Evolution has just got to wire them to have some way of psychologically connecting to people around them. Otherwise the species would perish in a generation. That's got to happen. So there's a starter pack here just as we've got a starter pack from evolution for the physics of the objects around us. We've got a starter pack that uses notions like belief and desire. That's what we naturally use in interacting with other people. But that is something that maybe there's a lot of cultural learning in it. It takes different forms in different places. But that's going to lead just as folk physics leads on to scientific physics. So folk psychology should lead you on to scientific psychology. And the question is are there limitations of folk psychology? Now notice incidentally that when I'm talking about folk psychology here I'm not just talking about your knowledge of what's going on with other people's minds. This applies also to your knowledge of what's going on in your own mind and your knowledge of what you're thinking what you're believing and so on. So that's something that starter pack of folk psychology just as much as you are using it in connection with other people. Now are there limitations to folk psychology? I mean are there analogs to the movement of the tides or the movement of the planets things that folk psychology things that are ordinary talk about in the mind just can't explain? Anything? Examples? My body problem is a good one You're sorry? Irrational behaviour What kind of thing do you have in mind? It's not that there aren't any examples it's that there are millions of examples right? So certainly because everything I said so far about folk psychology is geared to explaining everything in terms of rationality. So you've got something that's truly irrational then folk psychology is helpless you just can't explain it Are you giving that as an example of irrationality? Wouldn't apply actually yeah okay fair enough if you have if you have something where it's not your beliefs and desires making you do it then folk psychology is not going to explain that You might find that folk psychology your folk psychology just doesn't get a grip with them someone from a completely alien culture that is possible lying? lying might be highly rational it depends on the lying well yeah that's not always lying you might be perfectly sincere there but lying is often it seems to me highly rational when politicians lie nobody says they're being irrational the trouble is they're being all too rational look here's a list I think a phenomenon of church from the things what just happened okay okay maybe that is an example of the limitations of folk psychology I have no idea creativity how did Darwin come up with the theory of evolution how did JK Rowling come up with the Harry Potter stories how did you just have that great idea for an essay how did how did Robert Frost come up with the poems that he did well in folk psychology there is no way of explaining these things we just casually regard them as mysteries we say well we'll never get to the bottom of that it really is a fundamental problem there but that's not I mean we're used to regard that as a mystery but that doesn't mean it's okay to regard that as a mystery it ought to be possible to explain these phenomena association yeah okay we can put that as a theory of creativity the trouble you will have is in giving any prediction giving you a substance to the idea of which associations are going to be the ones that really matter here you could predict that but you would be wrong okay why are some people smarter than others I mean is that no one has the slightest idea why are some people smarter than others is it because of the way they were brought up is it because they went to Berkeley is it because they didn't do philosophy I mean there isn't a sensible theory here what goes on when people are dreaming why do we sleep I mean people have been working this very intensively why do we sleep and in particular was dreaming for and nobody has anything very good to say about it one theory is that when you sleep it kind of keeps you out of trouble when it's dark you can't see too good so if you sleep that kind of keeps you out of trouble that's not far from the state of the art yeah oh why do we get tired how come sleep helps with being tired yeah and once dreaming for what is all that about anyway why do we dream you might try anyone could try off the top of their head something about well emotional processing maybe something about cognitive reinforcement something as vague as that and then that's it that's where it runs out why do you have the dreams you do nobody has any idea folk psychology just can't address these things how come some people are good at basketball and some people are not good at basketball I don't know how come it's so hard to run to ride a bike well I found it very hard to run to ride a bike so how come there's so much variation and what's going on when you're riding a bike anyway from the point of view of cognitive psychology that is an absolute mystery there simply isn't a good theory of how people do stuff like riding bicycles um how does vision work if you want to understand I mean you get a 2D pattern on the retina and somehow that generates the whole rich visual world that you get around you what's going on there people's beliefs and desires just doesn't do it it doesn't begin to address how you get from the retina to the whole conscious 3D presentation of the world why do you get perceptual illusions like the moon seeming larger when it's at the horizon than when it's not why does that happen because your beliefs and desires why is it that if you draw two lines the same length and you do the arrow heads like this oh you see what I mean picture if you will didn't do that take it how come this line looks larger than that one because of what you believe in desire this is an artist's impression this is not the real thing is that because of what you believe in desire of course not but you can't see questions in terms of folk psychology for these questions you just have to move to a scientific analysis why do we remember the things that we do why can you suddenly be overwhelmed by the memory of something that happened when you were 12 just as you were walking down the street and another time you try to remember it and you just can't you rat your brains why does memory work the way it does again we can't do that in terms of folk psychology or to take one other interesting case if you take how people learn concepts how children learn concepts that seems like about a central question to how people learn as anything else learning concepts is really basic to any kind of interesting learning is the big hurdle children have to get over even at university is the big hurdle you have to get through learning unfamiliar concepts how do we do that you can't do it in terms of beliefs and desires because talking about what beliefs and desires you have presupposes that you have all the concepts it can't explain how you get new concepts now just as with physics there's a way of coming to physics that says let's forget the stuff about impetus let's have a fully general theory that applies to the planets that applies to atoms it applies to billiard balls it applies to the physical behaviour of waves out at sea and you do it in terms of forced acceleration and mass and so on there's another way to approach the explanation of human behaviour which is to say let's forget that stuff about beliefs and desires let's not talk about beliefs and desires at all let's look at self functioning let's look at the ways that assemblies of cells fire and how they excite or inhibit each other's firings then you can talk about a quite general theory about the basis of behaviour that will apply to every human and to everything that every human does because what you're talking about here when you're looking at the biological basis of behaviour are things that underpin any kind of human movement or action at all but they also don't just apply to humans they apply to any animal there are going to be general laws governing the ways that neurons work that are far more general than talk about belief and desire and that just won't give up when you're talking about perceptual illusions or memories or whatever it might be so there is available a much more general theory than folk psychology just as folk physics has available a much more general theory namely scientific physics so looking at it like that what we ought to be doing is replacing talk about thinking and believing and feeling with a much more general theory that can explain everything that folk psychology can explain but also all these other phenomena that folk psychology can't explain so if you think of it like that then believing, hoping desiring, remembering fearing, wishing loving, longing they will all go the same way as impetus there is no such thing as impetus there is no such thing as loving, fearing wishing, hoping any more than there is such a thing as impetus what it's going to turn out is that scientific psychology measures people that way of measuring people that way of calibrating people in terms of propositions it's just not that good a way of explaining and predicting other people we need a much more general approach talking about information processing in the brain that the subject might not be conscious of at all let me give just one other example of the limits of folk psychology here folk psychology can't explain we spent a while looking at schizophrenia in one class folk psychology just can't explain stuff like schizophrenia or delusions that psychiatric patients have when we say someone is crazy what you're doing is you're marginalizing them but looking at it from another way the other thing you're doing is flagging up, pointing out the limitations of your own theory of the mind because when you say someone is crazy what you're saying is my theory of mind can't engage with this person my theory of mind can't explain or predict what's going on with this person and if you're saying it for someone else's benefit if you say well she's just crazy what you mean is don't even bother trying to get your theory of mind to connect with this person because it won't do it that's not something about them that is wrong that is a limitation in your way of thinking of things just as with impetus you hit limitations in your way of thinking of things when you say someone is crazy what you're doing is you're putting them on a box and saying my theory of mind is not going to work for this person so you remember we had this case of a 22 year old woman who thought thoughts and feelings emanating from her mother's unconscious were being communicated to her when the rain drops that fell on her air conditioner so when the rain drops hit the air conditioner they went crack and the thoughts and feelings would be inserted into our mind can you explain that in terms of the beliefs and desires of this patient I mean it just kind of seems obvious you might try to cook up something Freudian but it seems obvious right at the start that this is not going to work so when Descartes says the certainty with which you know of your own existence is greater than the certainty with which you could know of the existence of any physical thing when Descartes says at last I have discovered it thought this alone isn't separable from me we did this in the very first lecture of this class and then it seems like this is just a basic certainty Descartes was surely right about that everything else might be an illusion but surely you know about your own thinking right? can you put your hand up if it still seems to you that Descartes was right about that you're certain about your own thinking even if everything else is an illusion yeah okay what I'm suggesting is that's really a big mistake you are not certain of your own thinking when Descartes says you're certain of your own thinking when you say you're certain of your own thinking what you're doing is you're just working within folk psychology Descartes is just working within folk psychology the same way you might work with an impetus theory and if someone says to me you objects don't have impetus physics has thrown out that notion of impetus but look impetus impetus if I do that does that demonstrate that things have impetus I just gave this impetus it doesn't at all all that's going on here is I'm taking the notion of impetus for granted and working within impetus theory and when I work with an impetus theory it seems so obvious sure there you go there's impetus at work and similarly if I take the notion of thinking for granted and use that and say look here it is, here's thinking going on that's just like tossing the duster and saying there's impetus for you you're saying look there's thinking what could be more certain than that but that just underestimates the challenge the challenge talking about impetus is not maybe you only think this object has impetus but it doesn't really and other things have impetus the challenge is the radical one that the very idea of impetus has to go out of the window and be replaced by talk about forced acceleration and mass and the challenge to the idea of thinking is not well maybe you saw thinking maybe you thought you got thinking here but well it wasn't really what you'd call thinking that's not the challenge the challenge is the whole idea of thinking has to go out of the window and be replaced by talk about what is going on with the biology of the brain yep they can't cope with, exactly and that's why we have to throw it out the propositional attitude psychology it just means that there's more stuff we should add to what we believe so it doesn't necessarily say that anything that we've learned through propositional attitude psychology is wrong it just means that there might be additional truths okay that's an important point the remaining question is going to be how does impetus relate to the concepts of scientific physics so suppose we say the more general notion is that we talk about forced and acceleration and mass and so on yep then we say but couldn't impetus be a local part of the picture you see what I mean? because it works fine within the restricted domain yep the question is going to be does impetus map onto any of these concepts like force and acceleration and mass that we know of what the underlying reality is yep and the reason impetus gets thrown out is it doesn't actually have any tidy map onto these underlying notions yep so if it did then you could say yeah impetus is just a special case but that's not what happens that's why the notion gets tossed similarly you could say the belief desire but just works within a certain limited domain let's hang on to it for that but we know what the general theory looks like it has to do with stuff about the biology of the brain and what we're learning I mean in a way something we've been psyching up for the whole term is that there is no tidy map from these talk about belief or desire onto anything put in terms of brain biology okay that's an important possibility I don't want to try and close that off right now yep one that's right but these are all psychological notions and if the challenge is folk psychology is wrong from start to finish there is a bad set of concepts to be using then he's really helpless against that challenge it seems to me you can't meet that challenge just by saying well it seems to me very certain that I'm thinking anymore then you can meet the challenge to the impetus theory by saying but yeah this is impetus surely you'd call that impetus yep well he I think when he's saying I think he means something propositional I think involves thoughts yeah it was just our propositions yep that's right I think that's exactly how Churchill wants to think about it but you could think of impetus as a working concept for daily life it's just that when you look at when you step back and look at what's literally objectively true then you're not going to talk in those terms yep so talking about beliefs and desires a good working concept helps us get around but it actually doesn't literally reflect anything that's really going on sorry yes we don't want to take it too you don't want to take it too seriously last one no no no no that is not correct there's nothing that is forcing it to keep moving right well gravity and inertia are there all right but they are different concepts to impetus nothing is okay that's fine what you're doing there is you're saying I could take this talk of impetus and think of it just as a re-description of what everybody agrees is actually happening I'm not telling you about the causes of things when I talk about impetus you could try defending folk psychology like that it's just a re-description of what's actually going on and it doesn't describe the causes of what actually happens for that you need to talk about brain biology it's really game over for our ordinary talk about the mind though because if you remember going back to when we were discussing behaviorism it's very important to our ordinary talk about the mind that we think about our motivations, our hopes our fears as being what make us do the things that we do it's not just a roundabout way of re-describing what we actually do it's supposed to be giving you insight into the causes, the springs of our behavior it's not wrong, it's not inaccurate it's not inaccurate if you say it's not about the causes yeah if you say it's not about causes and try to describe it and try to reinterpret it the way the behaviorists did just talk about what behavior is actually going on but what is going wrong is if you take it to be giving you any insight into the clockwork of the human being into what makes people like the way they do that's what it's been thrown out yeah but that's really important you really lost everything that we care about with the mind if you say love isn't what makes people do the stuff they do love is just a way of re-describing the fact that sometimes they act in those ways yeah I just want that if you think how how do we go next if this is right, if Churchlands are right Paul and Pat Churchland started developing this idea that ordinary talk about the mind should just be eliminated like a long time ago 30, 40 years is something like that they have been living with this idea for a very long time and at first to most of us it seems you just couldn't get by without talking about what people want, what people hope for and so on but there was a kind of interesting New Yorker interview with the Churchlands a couple of years ago where they quoted this from the course of the interview Paul and Pat realizing that the revolution during neuroscience they dream of the neuroscience that is going to replace talk about the mind realizing that this is still in its infancy they are nonetheless already preparing themselves for this future making the appropriate adjustments in their everyday conversation one afternoon recently he was at home making dinner when Pat burst in the door having come straight from a frustrating faculty meeting she said Paul, don't speak to me my serotonin levels have hit bottom my brain is a wash in glucocorticoids my blood vessels are full of adrenaline and if it weren't for my endogenous opiates I'd have driven the car into a tree on my way home my dopamine levels need lifting pour me a chardonnay I'll be down in a minute so there you go you learn to talk like that and you can eliminate talk about the mind I was actually talking to a student from Shanghai who told me that the last time he'd gone home he found that his friends were actually talking like this naturally that I think that's not an uncommon phenomenon that if you have the neuroscientific sophistication to talk like that then it can seem like a much more precise and exact way of describing what is going on with you and other people than talking about the mind Paul and Pat have noticed it is not just they who talk this way their students now speak of psychopharmacology as comfortably as of food so with that glimpse of the future central state materialism said beliefs and desires exist all right it's just that all they are are brain states this theory says beliefs and desires don't exist all there are are brain states right but on the other hand Churchill's point is you may be wrong you cannot draw bounds around what the science will do in that way I channel different people at different times I I'm not claiming consistency for absolutely everything I say throughout this class okay on that note we have to stop if you have comments please try and bring them to the front