 So today, we're moving straight on to talk about consciousness. I know you must be feeling a bit depleted right now, but we're not going to pause for breath. So today, we're going to look at Thomas Nagel's article, What Is It Like to be a Bat? I'm just going to show you. This is a bat hanging upside down. I think nobody knows why bats like to hang upside down. You'd think it would be the first thing that would be discovered, but it's actually not understood what they get out of it. Anyway, today is Nagel's article. And on Tuesday, we really move on to the state of the art, where Jackson will be talking about the Hain and Nakash's towards a cognitive neuroscience of consciousness. So this is quite a long article, longer than we usually have, but Jackson suggests skimming or skipping section three and skipping section five entirely. Do you want to make any comment about that? It's the boring part, but I'll go right in. One, two, and four. OK. OK, so that's on B-space. And it's a little bit ironic, because one of the main points of Nagel's article is that the idea of a science of consciousness makes no sense. And it sounds kind of G-whiz when you hear the notion of a science of consciousness. But if Nagel is right, the reason it sounds kind of G-whiz is it doesn't make any sense whatever. So let me set up Nagel's discussion here. The key notion, it seems to me, Nagel's discussion is a little bit abstract. And his main point is more abstract than you might realize first reading it. So really today, I just want to talk round his main point, which is about the importance of imagination in an understanding of the mind. So there is such a thing as having an imaginative understanding of someone else, being able to put yourself in their shoes. And right now, you can imagine what the room looks like to me. I can imagine what the room looks like to you. That's really important for ordinary social interaction. And one way to start trying to get at what Nagel's talking about is I think one way you could put it is the idea that there are two explanatory spaces. One is the explanatory space of our imaginative understanding of each other. The kind of understanding that a historian tries to get of their subject, or that you try to get of someone you know well. And on the other hand, there's a different kind of explanatory space, which has to do with finding out the laws and regularities governing the world around us. That's where science is. So a basic idea here is that there are two explanatory spaces. So let me try and fill that out a little bit. Suppose you think about the relation between chemistry and physics. Are there any chemistry people here? Anyone doing a chemistry class? Some? Good. OK, well, you can help me at various points here. High school chemistry. Many of you have done chemistry in high school? A little bit? OK, well, I'm going to tell you some chemistry the way I remember it. And the way I think the subject was around 1900, around 1900, the basic situation was that in chemistry, it was well known, it was well established that when different elements combined to yield compounds, they did so in characteristic ratios and characteristic proportions. So you get two parts of hydrogen combining with one part of oxygen. You see what I mean? You don't get one part of hydrogen combining with one part of oxygen or one part of hydrogen combining with 10 parts of oxygen. They combine in the ratio of 2, 1. So that was generally known. There are these laws governing the proportions that elements combine in. And one way of systematizing that is to give each element a number. Call that the valence of the element, right? You can do that. And then you can say why any two particular elements are combining in the proportions that they do by saying, well, this is a valence of 3 and that has a valence of 4. You see what I mean? So you've got regularities there governing the ratios that elements combine in. That's chemistry, right? Now, the thing is you could do that without knowing anything about atoms. You might not believe the atomic theory. Not every respectable scientist did believe the atomic theory of matter in 1900. Haber, who invented the Haber process, a really basic chemical thing that I didn't remember learning about in high school, did not believe the atomic theory of matter in the late 19th century. So you don't need to believe or even know about the atomic theory to give explanations like that of why elements combine the way they do in terms of valence numbers. But the great thing is physics did come to explain these phenomena. What happens is that physics explains this notion of valence in terms of valence electrons. When I was in high school, this was explained to me as gaps in the outer electron cloud. Does that ring a bell for anyone? That was how it used to be then, maybe not how it used to be anymore. So I don't really have the technical vocabulary to explain it all perfectly. But that notion of valence is given a physical explanation in terms of the structure of the electrons around the atoms constituting the elements, right? I mean, that's a little bit abstract. But you see what I mean? So what happens here is that you get a bunch of regularities in chemistry about the ratios in which particular elements are combining. And then physics gives you a deeper explanation of the very same phenomenon. The great physicist Rutherford said, there is only physics. All the rest is stamp collecting. He meant physics gives you all the general truths that are about the world. And the stuff that chemists do is just applying physics in this domain, or that is relatively boring, tedious stuff. You see what I mean? You only see what he means. So you're explaining the laws of chemistry in terms of physics. So when you say valence is, that what you're doing there is you're reducing chemistry to physics. You're saying chemistry has really turned out to be a branch of physics. And that kind of pattern, there's lots of examples we've thought about, lightning is discharge of electricity. If you say lightning is discharge of electricity, what that lets you do is all the phenomena that happen with lightning, why it's connected to thunder, why it's connected, why lightning can kill people. You can explain all that stuff by saying lightning is discharge of electricity. You already knew a lot of stuff about what lightning does when it happens and what it can do to you if you're out of the open and get it. But now you understand it better because you're told that lightning is discharge of electricity. Or if you take heat as motion of molecules, then there are lots of phenomena involving heat that anybody who's ever been in a kitchen knows about. You don't need to know about the atomic theory of matter to know how heat works. Lots of the stuff that heat does, it melts things. If you pour boiling water in a glass, it will crack. But once you say heat is motion of molecules, now you can explain all the phenomena that you knew about already at a deeper level when you say heat is motion of molecules. So if you say, why did this glass crack? Well, because you poured boiling water into it, anybody knows that's going to happen. Anybody who's used boiling water in my glass knows that can happen. But once you know that the water consists of a whole bunch of molecules and that the heat is a matter of those molecules rushing about very, very fast. I hope this is too technical. The molecules are going really, really fast, right? And when it's boiling, they're going very, very fast. And then they kind of bang in to the molecules in the glass. And they bust up the connections between the molecules in the glass. You see, I don't want to blind you with science here. But once you've got that, you understand why the heat does that to the glass much better. So you deepen the explanation. So the question is, is it like that with the mind? I mean, if you take the model of heat is motion of molecules, or lightning is discharge of electricity, or valence is a gups in the outer electron shell, then you should be saying something like that when you're saying the experience of redness is cell firing in V4. Pain is C-fiber firing. So what's going on there is, just as anyone in the kitchen knows about heat, so anyone in ordinary social life knows about the mind. You know a whole lot of stuff about the mind. But then when you get this knowledge of cell fireings in area V4 of the visual system, or pain being C-fiber firing, now you should understand everything much better. You should know why people behave the way they do. You're going to understand how people tick much better when you know these are reductions. But on the face of it, and I just want to say on the face of it, that's really not true. When you think about what you're looking for in psychological understanding of other people, I suppose you take a case where you just are in daily touch with someone that you don't understand at all. I mean, suppose you find yourself sharing a house with someone from a completely different cultural background than your own. They're from a different country. They're from somewhere with traditions or religions that you know nothing about. And you just don't know what is going on with this person. You see them in the kitchen in the morning. Are they happy? Are they sad? You have simply no idea. They do this chant now and then. And what is that? Is that something they do to cheer themselves up? Is that religious? What is going on? I just don't know, right? That can happen. That's not totally imaginary, that kind of situation. And then you say, well, actually, I've got a friend in MCB who has a brain scanner. So I can actually put this person into the scanner. I can get a full readout of their brain. At a physical level, I now know exactly what this person is going to do. I can see from the scan, wow, he's about to do the chant. Yeah, look, there we go. Off he goes, right? I saw that in the scanner. Yeah, that is that pattern of brain activity that makes him do the chant. Do you understand this person any better? You don't understand them a bit better. You have no insight into their psychology at all. What you wanted to know was, why is he doing that? What's going on in there? You have no idea, right? So even though it's as if, I mean, when you cut to a molecular understanding of boiling water, you already have a full grasp of why that's going to break a glass. There's nothing missing in your understanding. It's not as if, well, if only I knew about heat, that's the missing thing. That's not missing. Heat just is that rapid motion of molecules. Or I'll take another example. Suppose that there's a public figure you admire. Suppose there's some politician you admire. And at some point in her career, she made a disastrous mistake. She did something that was obviously crazy, very damaging. And you reading a biography, you want to know, what were you thinking? Why did you do that? Well, if at that point, the biographer said, but fortunately, she passed through a hospital at that point, and we have a complete scan of her brain. We know exactly what was going on. There were just these firings in the motor cortex that were going to make her sign that form. And you say, and now I get it. I've never understood what she was thinking there. But now I know that the cells in the pre-motor cortex were firing. Well, what else could she do? That doesn't give you the kind of insight you were looking for. This is not like chemistry and physics. So on the face of it here, you don't deepen the explanations by going down a level. So there's a kind of justification you have for saying that valence is gaps in the outer shell of the electrons, or heat is motion of molecules, that you just can't have for saying pain is C-fiber firing, or anger is activity in the amygdala, or whatever. One, two. That's right. Psychologists do do brain scans the whole time. That is the biggest single area in psychology is understanding the brain. But the question is, what kind of understanding are you getting from it? See, if you want to understand why someone is behaving in a highly deviant way, then a brain's something about the brain may help, really may illuminate. But it's not giving you the kind of understanding of what's going on in there. I mean, the whole thing of if you take someone who's speechless and doing simple repetitive motions, and you want to understand why that's happening, and you do a brain scan, and you find that their speech centers have been immobilized and that there's something going on with the system organizing the movements of the hands, then sure, you do get an explanation of that. But that is not the same thing as understanding why it seemed like a good idea, how it is from the patient's point of view. It's not telling you anything about that on the face of it. It's not psychological. It's not giving you any insight into their mind. It is telling you something about how a bit of the brain caused them to do that. But it is not giving you, as yet, just by doing the brain scan, you don't get any insight into what their mind is like. You see what I mean? Yep. Come back to that. Sorry? Yes. OK, OK. OK, that is a very good, if somewhat edgy example, right? But let me just pause in that a second. Let's just take why that's edgy, right? Suppose someone's really upset with you. And you say, why are you so upset? On the face of it, there are two alternative explanations you could give. One is, I did something completely outrageous. You have every right to be upset at me. Yep? Once I see the thing from your point of view, of course, what I did was just unbelievably awful, right? You have the right. I see that. I completely understand. I wasn't taking your point of view into account and what I did. Yep? Another analysis I could give is, you're very upset at me. God, it's those hormones. Now, that, too, is an explanation. But it's an entirely different kind of explanation. It's not one that is seeing things from your point of view. It's one that is saying, this is not something I can make sense of from your point of view. It's just something that you're brutally caused to do by the biology. So it's not a matter. It's exactly not a matter of projecting myself into your situation. It's a matter of distancing myself and saying, I'm not going to get a psychological or empathetic understanding of this. That's why it's an edgy example. Do you see what I mean? Because there are such, there are all these issues about respect and so on in that, in whether you're going to try. It's like, one of them is huge. Exactly. And just to put it, one is an explanation that this level of imaginative understanding, putting myself into your point of view and seeing why you're upset. Another thing is saying, well, there is these laws governing the behavior. That's what happens. These are quite different. And it doesn't seem like one can be reduced to the other the way that the phenomenon of heat can be reduced to motion of molecules. There were a couple of other questions. Yes, right. Right. Right, sure. Yes. Yes. OK, that's very good. And that connects to that first question about what are psychologists doing when they put patients and scanners? The thing is that what you're doing in that kind of example is you're using the stuff from the amygdala to give you insight into the psychological level. Really, at the end of the day, you could cut away the stuff about the amygdala. You could just say you would get the insight just from knowing she was concerned about her family. She was thinking only about that. And she was really angry at what was going on. That's why she did that, right? Now, the amygdala is not essential there. The amygdala just drops out. The amygdala was just a prop to let you know it was anger in the family that were the key things. And your psychological understanding is all at this imaginative level. So it's not like the molecules in the glass case where you really understand how the water broke the glass much better by getting the analysis in terms of molecules. All that's going on here is you've got an auxiliary prop to let you get into this space, not that this itself. I mean, to put it another way, when you think of heat and motion of molecules, at the end of the day, you could eliminate the heat. You could say, just forget about that stuff about heat. We can do it all directly in terms of motion of molecules. The other reading of your example than the one you gave would be to say, let's just forget that stuff about the family and so on. Let's just say it was the amygdala. That made her do it. That's the thing that doesn't actually, in fact, give you any insight. But that's a very good point. There was someone else. Yes? I thought you had a question, but maybe you didn't. How does a glass feel? Yes. That's right. I don't agree at all. You can get into someone else's mind. We do it the whole time. Well, that's right. But that's what we do in this little chat, for example. You know, we try and understand what the other one's saying. If you couldn't do that, then ordinary conversation would be impossible. Well, this is why imagination is such a key thing. That is what you do in a conversation where you passionately disagree with someone. I mean, if you're being reasonable about it, you try and get there, taking things. You try and see how the world seems to them. That is the point of hammering away about imagination. It's really, I think in practice, nobody thinks it's true that you just can't do it. I mean, otherwise, social life would just fall to bits. Yes. Yeah, that is a really serious point. OK, I'll come on to this in a second. What? Doesn't it apply to anything in the world? Doesn't what apply to anything? I actually don't accept any of that, really. But if you just take something like pain and suffering, say, the idea, if you take what you're saying to its logical conclusion, then the idea would be that I can't empathize with someone else's suffering. If I say something brutally rude to you and someone says, how would you feel? How would you? I mean, this is the question that small children are being asked the whole time. How would you feel if someone did that to you? Now, you could say, oh, well, I mean, maybe they're feeling what I feel when I feel pain. Maybe they're feeling what I feel when I feel suffering. But for all I know, they're unimaginably alien. I mean, so what the hell, you know, I'll do what I like. How would you feel if you were insulted like that? Well, maybe that's got nothing to do with what the other person feels. It's not the same in every way. In every way. It's not completely the same, no. But that you can have an understanding of how the other person feels. It's true that different people have different levels of tolerance for insult, for example. But part of growing up is you get to understand that. You know that. You can adjust for that. That's just how people, that's just ordinary variation between people. That's part of the thing about understanding someone from another culture. That may be something that at the age of six, you would have been completely unable to do. You bring up someone who's just radically different. But just part of growing up is you get better at that. You get more flexible in what you can expand on. OK, so that's just an initial pass over the thing about two explanatory spaces. Nagel has, the title gives you a very famous example that Nagel gives, that really tries to ram home this point. And I'm really just going to be talking only about this point today. Because if it's right, it's so important. And it's pretty plausible. So Nagel's key idea is that consciousness is knowable only by imagination. If you only write down one thing I say, then that would be it. Consciousness is knowable only by imagination. Other people's consciousness, as the last question that I was saying, it can be difficult, it can not be easy. But insofar as you can know about someone else's conscious life, it is only by the use of imagination. So let me give a couple of key quotes from Nagel. These are very abstract, and they may not make sense in the first pass. But I just want to give them now because they're so key and maybe they'll come into focus. So Nagel says, the subjective character of experience is fully comprehensible only from one point of view. That is the point of view of the person who's having the experience. So if I want to understand the subjective character of your experience, I have to understand it from your point of view. And if you shift to greater objectivity, if you shift away from attachment to a specific viewpoint, that's what objectivity is when there's no particular viewpoint in place. Then getting an objective picture of what's going on doesn't take you closer to the real nature of the phenomenon of subjective experience. It takes you further away from it. So the key things there are that the subjective character of experience is fully comprehensible only from the point of view of the person having the experience. And the real nature of the experience can't be understood objectively. At present, we are completely unequipped to think about the subjective character of experience without relying on imagination, without taking up the point of view of the experiential subject. So here's some glossing that basic point. That's his basic point already. That's really the whole thing in a few words there. The fact that an organism has conscious experience, the thing about the glass, the cracked glass, someone said, well, what's it like for the glass? I mean, have you thought about the glasses point of view when all that boiling water rushes in? How would you like it? Well, that's kind of comic, because of course, I mean, there's nothing it's like for the glass. If you have conscious experience, then there's something it's like to be that organism. An organism has a niggle rounds out to an equation. An organism has conscious mental states, if and only if there's something it's like to be that organism, something it's like for the organism. And then he gives us an example of the bat. Anyone who has spent some time in an enclosed space with an excited bat knows what it is to encounter a fundamentally alien form of life. I mean, have you guys encountered bats? They are really very spooky animals. I mean, they kind of move in this jittering, irregular way. You can't quite see what they're looking at. I mean, that's what's a comic about this picture, actually, that it looks like the bat sniffing the flower or something. But I mean, for all you know, it's not perceiving the flower at all. You know, they are really strange animals. I once talked to a student who was, this was an England rugby player and a very large guy, weighed about 15 stone. And he told me that he'd been woken up late one night by a bat getting into his bedroom. And like I say, this is a very large guy. He said he didn't think about it at all. He just opened his eyes, saw the bat, and shot out of the room down the corridor and into a cupboard where he shut the door and stood there, palpitating in the dark. And then after a bit, he pulled himself together and opened the door a crack. He thought, well, it's only a tiny little bat for God's sake. What am I worried about? He opened the door a crack. And the bat had got out of his bedroom and was making long swoops up and down the corridor. So he shut the door again. They're really strange animals. I mean, part of it is that their sensory apparatus is so unlike yours or mine. I mean, they're using this ultrasound that booms out. They're not using vision. They're using this thing that booms out very large pulses and listens for the reflections coming back. So it's kind of complex what they have to do because they boom out the stuff at such large energy levels that if they were listening while they boomed out the pulse, they would be deafened. But they've got to be very sensitive to listen to the echoes. So they've got to be switching on and off their echolocation, their receptors while they're booming out those pulses. It's got to keep going on and off. And they're getting those waves back and figuring out where everything is. And they've also got to negotiate with each other. So they've got to avoid jamming each other. It's a very weird mental life. And Nagos' point is if you try and imagine what it's like for the bat, if you're trapped in a barn with a bat and you're thinking, well, what is going on there? Well, you're restricted to the resources of your own mind. And those resources are inadequate to the task. I was saying you can make adjustment for getting into the mental life of someone from a different culture or getting into the mental life of someone whose interests are quite different to your own. Preferences are quite different to your own. But with a bat, it's just too far off. You can't do it. And if you just try right now, imagining what the room seems like to someone else, or if you're trying to imagine how does this lecture sound to someone else in the room? Are they going to be violently disagreeing or sound asleep or whatever it is? Then you can do that. But it's really different with a bat. The other person's take doesn't have to be the same as yours. The bat is quite alien. And Nagel points out, you can, after all, imagine. You can indeed imagine being shrunk and strapping on wings and maybe getting to be in as bat-like a position as you can. But to the extent that you could look and behave like a wasp or a bat without changing your fundamental structure, that's not going to tell you. You could strap on bat wings and hang upside down by your feet, but that is not going to give you any insight into the mental life of the bat. But on the other hand, if you said, well, of course, I could imagine what's going on with the bat if I just swapped out my brain and put in bat sensory perceptors and so on, well, all you've done there is kill Nagel and put in a bat brain instead. You see what I mean? It's not really clear that it makes any sense to suppose, well, if you just swapped out my brain and put in a new one, then you'd know what was going on. I mean, you wouldn't be around anymore if that happened. And then what that means is that there are limits on what we can imagine. You can imagine the mental life of someone from a different culture. You can imagine the mental life of someone whose political views are quite different to yours. But there are limits. So that means that there are animals whose conscious life we can't imagine at all. We can't conceive of what the world is like from their point of view. You can usually do some rudimentary thing. If you're looking at a bunch of penguins, you could be saying, well, that one seems to be hungry, or that one seems to be grumpy with the other one. You can have some kind of schematic understanding. You could do some kind of schematic psychology of them. You could say, well, there's some kind of pain or some kind of hunger. You could say, well, don't they get cold? I mean, isn't it cold when you do that diving and stuff? I mean, what's it like? But we take it for granted, I think, that in each case, there's a specific subjective character that detailed inner life of the penguin that is just completely beyond you. So there are these limits on our imagination. And that means that there are facts about the world. There are truths about the world that we can't know to be true. Truths about how the bat is feeling or experiencing things right now, and we can't even understand them. We don't even have the concepts of bat psychology or penguin psychology. So these truths are forever going to be elusive to us. We can never get onto them. But the thing is, if you think about the scientific understanding of the bat, bats are intensively studied scientifically. All the stuff that people were saying about brain imaging or any kind of experiment you like is done with bats. You could tear the bat brain apart, sell by cell, and achieve a complete mapping of the bat brain. You could find out exactly how the bat sends out its pulses, how they get reflected by insects, how it knows what's an insect and what's a wall, for example. You can do all that. You can have a comprehensive scientific understanding of the bat. But are you going to know the first thing about what the conscious life of the bat is like? Of course not. It's not going to tell you anything of that stuff that seems so baffling, that seems so alien about the bat. So a scientific understanding, of course, is very fascinating, and it will tell you a lot. But it will not tell you anything about the inner life of the bat. Well, I mean, schematic in that you can use notions like pain or hungry, right, there. But if you think about the full, rich, buzzing, blooming confusion of your sensory experience and your inner life right now, the whole complexity of it as you see all these people, your reactions to all these people, it's a social situation. You're looking at people's expressions and so on. You're getting their psychological characteristics. At the same time, you're trying to get this hard idea. You're flicking back and forth to the screen, right? That kind of detail you don't have any knowledge of what is going on with the penguin. You don't have that detailed, specific knowledge of all the particularities of penguin experience. You can't have a kind of schematic level say, I think that was hungry. That's why it's gone fishing. But that's not the same thing. Plain as day? OK. Well, I said imagination a number of times. I want to try to talk a little bit about what imagination is. I mean, I think it's very intuitive, that notion. But it's not easy to be fully explicit about it. So putting yourself in someone else's shoes, an old song by Joe South, well-covered by Elvis Presley, that goes, I'm going to try and sing it. I'm tempting. Walk a mile in my shoes. Walk a mile in my shoes. Hey, before you abuse, criticize, and accuse. Walk a mile in my shoes. There's that sense that to do justice, before assessing someone else, you should understand how things are when you're in their shoes. I'm not making that up. That is a very popular idea. Yeah? Yes? Nobody has heard that song and said, I have no idea what you're talking about here. That's such a comprehensible sentiment that you need to know what it's like in my shoes. So what's going on there when you try to know what it's like in someone's shoes? Look, here's one model. I don't know that this is the right model, but think about this. This might seem like a kind of unlikely comparison. But suppose you want to know how an aircraft, suppose you're designing an aircraft and you want to know how it's going to behave in high winds and turbulence. Then there are two ways you can do it. You can try and write out the aerodynamics of the situation and from equations predict what's going to happen to the airplane. Another thing you can do is build a scale model of the airplane, put it in a wind tunnel, and see what happens to it, do the wings fall off? You see what I mean? Is that OK so far? Yep, thank you. OK, so that's a scale model of the real airplane. You're using that to simulate the real airplane. You're saying this is kind of like the real airplane. This is going to behave the dynamics of this thing and wind are going to be kind of like the dynamics of the real airplane. So let's see if his wings fall off. If he stays on, likely the wings of the real airplane will stay on. So you can contrast, similarly, the way you might explicitly write out how someone's going to behave, the functional structure of someone. If I'm really interested in you, I might make a box and arrow diagram of you. I might say, you know what, always make some mad. You know, when I do my boxes and arrows and I say, praising Bill always makes him really mad, right? So I got a box and an arrow there. I could do that. But the other thing you could do is just use yourself as a model of the other person to predict their behavior. That's to say, I mean, suppose you're told that someone you know was at home, alone, working, and then they hear the sound of footsteps in the basement. No one should be there. OK, what are they going to do? Freak out. OK. Exactly, right? You know what they're going to do. Yeah? Now, how do you know that? Because that's what I would do, right? So what you do is you use yourself like the model airplane. You say, let's suppose it was me getting that input sound footsteps in the basement. What would I do? You run that simulation. You see you feel yourself freaking out, right? There's a sense of which you've got to run the simulation offline, right? What I mean is you have to run it to the point where you freak out, but you don't want to actually be ringing the police or yelling or whatever you do at that point, right? You know what to really be doing just because you're imagining it. If you see what I mean, you have to take it offline, in a sense. Do it in your head. So if you think of this as like your functional structure, you're taking it that your functional structure, so this is what in the business we call a Rutgers model of the mind, where you have a belief box and a desire box, and you characterize everything functionally. They're a decision making, a practical reasoning system, a perception coming in, inference coming in, a body monitoring system. So you have your functional structure. The other person has their functional structure. And what you can do is put in pretend beliefs and desires. You can put in a pretend belief to your own system of there are footsteps in the basement. And then you can run that through the rest of your own beliefs and desires, and you get your freak out coming down here. You see what I mean? And you just take that, make sure that's offline. So you use your own functional structure to model someone else's functional structure. That's one thing it can mean to put yourself in someone else's shoes. Imagine you heard footsteps in the basement, just as that commenter said, what would you do? That's how you understand other people. You have to be able to make some adjustments. I mean, you can change some of your beliefs and desires. I like to be insulted. You can put in a pretend desire like that. But most of your beliefs and desires are going to be the same. Yeah, do you have a question? Yes. You can make these adjustments. Yeah, the way that works here is you can put in a lack of fear, a lack of concern for your own safety. Yeah, that can be factored into something pretend. But of course, if you just think what your ordinary common sense understanding of the world involves, there's just such a ton of stuff. You know that a chair will support your wet. I mean, once you start beginning to spell out the common sense things you know, you know that you can get through a door by pushing the handle, you don't make all that stuff explicit. You have all that stuff. You assume the other person has all that stuff. And that's part of the background here. You don't need to make all that explicit. It's like with a plane. It's a very laborious exercise to do all of aerodynamics explicitly, to make sure you've covered every aspect of the situation explicitly. Make a model. You don't need to do that. Similarly, if you can just assume the other person is human like you, pretty much like you. And there are these relatively superficial differences, like how brave are we. But their big picture of the world is just the same as yours. Most of the desires are the same as yours or the same type as yours. Then you can run that to predict what you're going to do. So that's simulation. Using your own box and arrow structure to mimic, to model someone else's box and arrow structure. I mean, I'm just using that. I'm kind of defining that as simulation. Does that make sense? Is that clear what simulation is? So you can see why that would be a big part of understanding other people, because that will be what lets you predict what they're going to do. You just run their inputs onto your mental life, making a few pretend adjustments, and then you know what they're going to do. But the thing is, the idea Nagle wants, the idea that seems so important for understanding of the mind, seems to be more than this. I mean, putting yourself in the other person's shoes, getting their point of view in the world, getting their perspective, there seems to be more to that than just being able to model their box and arrow structure. If you think about Bloch's robot, remember that robot with a billion people in it that is functionally just like you, could you model the robot in this way? Could you model a functional structure of the robot to predict what it would do if it had heard footsteps in the basement or whatever? Could you do that? Yeah? Suppose a robot heard footsteps in the basement. What's it going to do? Well, it's already programmed. Remember, it's programmed just like you. It's going to do the same thing as you. That's right. So you can just run it. You can say, what would I do? I'd get a baseball bat and I'd head down to the basement. So if that's what you do, then that's what the robot's going to do. So you can model the robot on your own functional structure just as well as you can model another human's functional structure on your own. But that doesn't involve imagining the robot's mental life from the inside, because the robot doesn't have a mental life. The robot doesn't have an inside. It's functionally just like you, but it doesn't have that. Or if you think about, as someone mentioned earlier, the inverted spectrum, suppose that Bill has a spectrum that is an inversion of Sally's. So there's Bill, there's Sally. One's got this. One seat gets those sensations when they look at the fruit. The other gets those sensations when they look at the fruit. So can you simulate what Bill and Sally are doing? Well, sure. Because they're both functionally just like each other and just like you. But their spectrums are inversions of one another. So when you're trying to imagine their mental life from the inside, what you do is actually very different. Imagining Bill's getting these sensations is very different to imagining Sally getting these sensations. And that's not a matter of functional structure. That's something more than functional structure. So when you're talking about walking a mile with someone else's shoes, you're talking about getting the throbbing beating heart of their sensory experience, their emotional take, their angst, their hopes, their joys in a way that goes beyond box and arrow structure. It's more like why they have the box and arrow structure that they do. And something like that is the notion of imagination that Nagel is wanting. It's got to include stuff like simulation, but it's more than that. It's capturing just what it's like in there, OK? Played his day? Some questions I know the answer to. I can do that one. Is that all perfectly clear? Yes? Yes. Just from the point of view of figuring out what they're going to do, you don't need anything more than box and arrow structure, because that will give you the whole thing about what they're going to do. But the thing is that two people could have the same box and arrow structure, so they'll do exactly the same things, whether or not they have the same spectrum, yeah? So when you're imagining this one's mental life or that one's mental life, that's going to be different, even though functionally it's just the same, yeah? That's the real point I want, that the understanding someone else's conscious life seems to go beyond simulation, because what you're trying to get is exactly how it feels in there, what the experience is like in there. No, at the end of the day, I would say we can do that, yeah? We can know really what's going on in someone else's mental life. I don't really believe the arguments about the inverted spectrum is the truth, but I think if you think of pain and pleasure, it's clear. The inverted spectrum is a very special case because you really can swap around the colors and everything be symmetrical, yeah? If you take pain and pleasure, pains and pleasures are not organized like the colors on a nice spectrum that you could map them round on. Do you see what I mean? If someone felt pain where you feel pleasure, they'd react very differently, yeah? Usually you don't get inverted with the mental life generally. You don't get inverted spectrum scenarios, yeah? So knowing about someone suffering, I think it would really be the wrong answer. If you heard this song, walk a mile in my shoes, walk a mile in my shoes before you abuse, criticize, and accuse, walk a mile in my shoes. As you said, but of course, nobody can ever know what's going on inside someone else's shoes. That would both be the wrong answer, and it would just seem completely blind to the reality of what goes on in everyday life, which is that we do understand what's going on in other people's shoes. And you can really be accused or criticized for not empathizing with someone else, yeah? It really makes sense that you could insist on being understood. Does that make sense? Yeah, OK. So I would note for a moment, say it's unknowable. I would also say it's the most important thing. That's the thing that really matters is understanding what it's like in there. And I think if you meet someone, if you meet a friend you haven't seen for a couple of years, and you say, how are you? What you want to know is not how you can push their buttons or how to predict what they're going to do. What you want to do is get some understanding of what's going on in there, how life is for them. That is the thing you care about with other people, is what life is like from their point of view. You want to get an imaginative understanding of their point of view. I mean, it's just too egocentric to say, of course, I'm only imagining what it's like for me from your point of view. There's not quite the right way to put it. What you're trying to get is really what it's like for the other person. You have to model them on you, that's right. But you're trying to get what's really going on in there. To think otherwise is really just to regard other people as if they're projections of your own psyche. And that just wouldn't be right. That's not how we ordinarily think. There was someone else. OK, one, two. You could put it like that. I was saying simulation is when you just do the functionalist thing. So that's just kind of a stipulation in my part. I mean, you can use the words however you want. But I was saying, you can model someone else's box and arrow structure by using your own box and arrow structure. That's a purely functionalist thing that you could do with Bloch's robot. So that's what I was calling simulation. But then I was saying, when Nagel was talking about an imaginative understanding of what it's like in someone else's mental life, he means to go beyond that. He wants to know something about the world of free songs and joys and pangs and pains inside someone else's mental life. Yep. I mean, they have different brains. And yet, they have different brains. So they're genetic, but they're different in there. Absolutely, yeah. But like. Well, there are going to be cases and cases. It might be negligible, and it might not. How different the cases are. But what people usually say about twins like that is that they have this incredible understanding of one another. There is a kind of limit of the kind of understanding that one person can have of another. People talk about telepathy, as if they were telepathic. And what you mean there is just this kind of imaginative understanding of one another is something that they have to the hilt. So there are a couple of people said, are you saying we can't ever have this kind of knowledge? I really mean to be saying absolutely we can't have this kind of knowledge. The puzzling thing is to understand what it is and how it connects to a physical understanding. Because your twins, they don't need to have done brain scans, right? But they can know each other's lives as fully and completely, each other's mental lives, as fully as completely as you can ever know someone's mental life. You don't need a brain scan for that. It's not even going to help. A brain scan is something else. These are all important points that people are raising that we will come back to. I don't mean to be just brushing aside any of those comments. They're all kind of live. But let's look at what this implies for the possibility of a science of consciousness. So remember on Tuesday we're talking about the science of consciousness. Well, what is science in these terms? Science is trying to describe the world objectively. That's the whole glamour of science. It's not anyone's point of view. It's just the hard objective facts. Not anyone's take on the world. So science is trying to describe the world that you have a point of view on. It's not trying to describe your point of view. It's trying to describe something that's independent of anyone's point of view that you just come in and take a look at. So here's Nagel. Every subjective phenomenon, every phenomenon of the mind, is essentially connected with a single point of view. And it seems inevitable that an objective physical theory will abandon that point of view. So if you're going to have an objective study of the brain, then that has just got to leave behind subjectivity. That's the whole point. You're getting some objective hard facts here. Not someone's subjective taken things. So the understanding that we have of consciousness, the understanding that we have in everyday life, the kind of understanding that you or I have of each other that you don't have of a bat, that isn't something that you could get from an objective description. I mean, if you can give a functional organization, a description of the functional organization of the bat, you can give a fully objective scientific description of the physiology of the bat. None of that stacks up to having that subjective imaginative understanding of the bat. That is just a different thing. Different explanatory space. So when you look at it hanging upside down, you couldn't, in principle, get to discover exactly why it's hanging upside down physiologically. What advantages that gives it, if any. But what is like in there when it's hanging upside down, you are never going to get. These are just two different spaces, two different styles of explanation. And you don't deepen one by moving to the other. You just change the subject. So could you give a scientific account of human consciousness? Well, I said that phrase of science of consciousness is pretty jazzy, but when you think what it means, a scientific account is one that doesn't depend on any point of view. That's what it is to be scientific, right? It's an objective description of the world. But if it's an objective description of the world, then it's not describing a specific point of view. But if its consciousness is all about a specific point of view, that's the only thing that's there. So there can't be any such thing. Could you explain in functional terms what it is to be conscious? Could you explain in physical terms what it is to be conscious? Of course not. Functional or physical are objective scientific notions. They relate to the objective or scientific level of description. So you can't, in those terms, explain what it is to have a subjective take on things. So you can't give a scientific account of consciousness at all. It makes no sense. As I said, it sounds kind of jazzy. And the paper we're doing next time is Towards a Cognitive Neuroscience of Consciousness. Does that make any sense? But I promise you this is really the edge of how people are thinking about consciousness today. But there is such a question as to whether it's even coherent. Isn't it just a contradiction? Do you want to comment now, Jackson, or do you want to hold fire? So there's that notion, a scientific account of consciousness. But if the line I've been pushing is right, it makes no sense. Is that OK? You don't have to agree with that, but is that clear? What the argument is that it makes no sense? And notice that at this point it should be very clear that dualism really misses the point. Dualism gets it that you can't really understand how the subjective phenomenon of the mind could be the same thing as the objective physical stuff. Dualism gets it. I can't see how the mind could be physical. The mind is view-pointed. Anything physical can be fully understood objectively. The mind can't be understood objectively at all. And dualism says, OK, I get it. So the mind can't be physical. So it must be made of something non-physical. It must be made of some ectoplasm, some ghostly stuff. But that ghostly stuff is just more objective stuff. What you're doing there is saying, I don't get it how this could be objective physical matter. So it must be objective astral matter. But that's not the puzzle. The puzzle is, how could the mind be made out of something that's objectively there at all? And if dualism is just missing the point there, it just substitutes one objective stuff for another as if that solved the problem. But it doesn't even begin to engage with it. Because the point we are at is actually completely baffling. The whole world, there is nothing more to the world than what is objectively there. But the position we've reached is that the mind is not in that catalogue. And you can't solve that problem by postulating a separate level of stuff that is objectively there. Because that just gives you the same problem. How can something that is only subjective experience, subjective points of view, be there in the objective world at all? And on that note, we'll pack it up till Tuesday. OK, thanks. Great questions.