 OK, hello. Good afternoon. Let's start. So today, we're looking at the inverted spectrum, and in particular, Martina Nidarumalan's piece, Pseudonormal Vision. That's really a little bit more technical than you really need. I'll try and explain the basic points here relatively straightforwardly. The inverted spectrum is supposed to be a problem for functionalism. On Tuesday, we'll look at Nagel's article, Brain Bisexuality and the Unity of Consciousness. The Nagel article, now don't be taken by surprise by this. The Nagel article is not in the Chalmers collection that all the pieces we've looked at so far have been. The Nagel piece is in the small blue book, the Peri Personal Identity Collection. Does anyone have a copy of the Peri with you? I mean, no. OK, so a picture, if you will, of a small blue book. That's the Peri, right? This is in the small blue book, not in the big blue Chalmers book. So today, I just want to start out by saying what spectrum inversion is. And once I've said what spectrum inversion is, I'll review what functionalism is and how we got to it, and then look at questions about what kind of problem spectrum inversion raises for functionalism. OK, that's the plan, spectrum inversion. Well, to start with, people talk about qualia in this literature. I gave the example of a Chinese barn last time, the feeling you get when someone does that thing to your arm. So for qualia, I don't really know, for color qualia, I don't really know of a better way of explaining it. And to say, look at those colors right now and reflect, if you will, for a moment on the sensation you are having as you look now. This one, now that one, now that one. So reflect, not as it were, on whatever's out here, but on the color in here, in your head, in your mind, the sensation you are getting as you look here. So the sensation you are getting as you look at this, now at this, now at that, that's the quali. That's a singular quali. Yes? Austin, Jackson, is that a singular quali? OK. But it's usually used in the plural qualia, meaning many quali, qualies. Qualia, you see what I mean? OK, so is that perfectly clear what color qualia mean? The sensation you get when you look at a particular color. So here's a possibility. Suppose you wake up one morning and you find to your amazement that all the colors of the objects have changed. Everything looks different in point of color. The sky seems to be red. The fire trucks are blue. There's been a systematic change. All the people look different. No one else seems to notice anything different. And it seems to be something that's idiosyncratic to you. Excuse me a second, I'm just going to push this out of the way. So yesterday, you were looking at a fire truck and it looked like that. That's how fire trucks regularly look. This morning, you woke up and the fire truck looked like this. How distressing. How amazing. So are your qualia the same or different? Are your qualia the same or different when you look different? That is the right answer, right? So the qualia have all been swapped round. The color qualia have all been swapped round. If you look at it again, are the shape qualia the same? Yes, are the size qualia the same? It is only the color qualia that are different, right? Yep. Do you want to take a minute to just check that? This is fun. It's only the color qualia that are different. Now at first, that's naturally going to be very distressing and upsetting or maybe kind of mind blowing. I mean, it depends on your temperament, I guess. But at first, when you're looking at an object like this and you're asked what color is that, you're going to give the wrong answer, right? But after a little bit, you will learn to use the word red in connection with that appearance. Yeah, you'll get the hang of it after a bit. You, if you're reasonably skillful, will start to use the color words for just the same objects as everybody else. It used to be you used red when you confronted with something like that. Now you use red when you confronted with something like that, right? So your use of color vocabulary will start to be the same as everyone else's. So at first, your use of the color words is disturbed and different to everyone else's. You're given all these wild sites and you don't quite know what to make of them. But then you learn, you adjust and you use the word red in connection with fire trucks. You use the word blue in connection with the sky, just like everyone else. And maybe after a bit, you get amnesia for the change. This whole thing was so distressing and traumatic that you actually just blot out your memory of the change. So you paint, you discuss the colors of things with other people and nobody notices that you're in any way different from anyone else. You pass all the tests for having good color vision. If you go for a checkup and they take a look at your color vision, you do just fine. You report the crimson things as crimson, the maroon things as maroon, the scarlet things as scarlet. But even although you talk just like everyone else and even although you discriminate objects just like everyone else, are your color experiences the same as other people's? No, they're completely different, right? I mean, will I do that again with a fire truck so you can see the difference? You see what I mean? It's just radically different from everyone else's. But you are talking and reacting to the world around you just the same as everyone else's. Now the thing is, maybe you were born that way. Maybe this didn't happen just one morning. Maybe you've been like that since birth. How would you know? There isn't any way to know. How could you know? What tests would you do? They take you, the doctor runs the checks. They say, can you tell which of these is which? Can you see the number five in this display? And you do absolutely fine. You tick all the boxes for having healthy, regular color vision. But your color experiences are different to anyone else's. I mean, you might say, well, there are some differences after all that might stick with you in the case where it just happened one morning in adult life. I mean, people talk about red things as being warm or reds used as a sign of danger. Blue is described as cold. Green is described as relaxing. So you might say, the world's gonna feel emotionally different somehow because the emotions I associate with the colors will be different after this change. But there are two things about that. One is presumably a lot of that emotional connection to the colors is something you learn. I mean, red is a color of blood, for example. Red is a color of fire. So presumably different, blue is a color of the sea. So presumably a lot of the emotional differences that we have between different colors have to do with what you regularly associate them with. But of course, if you're born with your colors all around, your color qualia all around a different way to anyone else, then all the emotional associations you learn will be around the other way too, if you see what I mean. I mean, because you'll be learning that what you experience is red, which is quite different to anyone else, will be associated with the same blood, fire, and so on as everyone else. So the general point here is, I mean, actually, can I just ask you, how many of you have had this thought already? Right, I mean, I think it's, yeah, I don't think it's a wild thought. You know, it occurs to most of us at some time that how do I know what's going on in there? So just to spell this out explicitly, what's going on with spectrum inversion? The idea is there could be a systematic shift in your color experiences that keeps their structure. So what you want to do is, if you're going to set up a case of spectrum inversion, is find an axis on which all the colors are symmetric. So what I mean is we talk about yellow and green and blue and red as being unique colors. Unique in the sense that orange is a bit of red in it and a bit of yellow in it, if you see what I mean, whereas red doesn't have any other color in it. Yeah, primary colors, the same, yeah, that's what I mean. So what you would really like is to map primary colors onto primary colors. So you map the green onto the red, you map the yellow onto the blue, but you could keep the same structure for all the colors. You see what I mean? So which colors are in between which? Which colors are lighter or darker than which? You keep all that structure. So there's one way you could do it. You could try mapping colors like that, but there are lots of other shifts you could try. These are from Alex Burns' article on inverted qualia. So it could be that what you're getting when you look at the bowl of fruit is that, that's what you get when you look at the bowl of fruit. Another person could be looking at the same bowl of fruit, getting this kind of color experience, getting the kind of color experience you get when you look at this scene, if you follow me, do you follow me? You and the other person are looking at the same bowl of fruit, but the other person's not getting what you get when you look at the bowl of fruit. The other person's getting what you get when you look at this. Or maybe they're getting what you get when you look at this, or what you get when you look at this. Now, the two of you could have just as fine color discriminations as each other. And when you bring asked, which ones are in between which ones in color? You could be giving exactly the same answers. So the structure of your color experience could be just the same. So the point is, there could be a systematic change in your experiences that kept the structure of the colors. It could keep which colors are in between which, which colors are lighter than which, which colors are purer than which. All that makes perfect sense, yes? That really, I mean, there's no trouble with the idea. Just to give a very simple example of this kind of thing happening. Suppose you have someone who has only black and white vision, right? There are people who just don't see color. They just see everything in black and white. So suppose you have two people with only black and white vision. Then it could be that what one sees as black, the other sees as white and around the other way, right? So one is getting this, the other is getting that, right? Right? So there is very clear that the structure is kept. And the way they talk will be exactly the same. But their experiences are different to one another's. The qualia are completely different. Yes? We all on board with that? OK. So if you can make sense of waking up one morning with all the colors and the fire engines in the sky and all that looking different, then after you wake up and you have that change, well, one possibility is that what happened is that earlier your color experiences were different to everyone else's and they've now been regularized. You've just stepped into line with everyone else. Or maybe they were the same as everyone else's before the change and you woke up and now you're one in a million. You're just right out of step with everyone else in which color experiences you're having. Or maybe you were different to everyone else before you woke up and maybe you're different to everyone else now too, right? Only scenarios are possible. So suppose your color experiences at the moment are different to mine in this way. Could you tell? Would you have the slightest idea? Is there some test you could run? Right, we use the same word. We call it green, whatever the sensation. Yeah? Yep. I agree if you just swapped red and green. Yeah, but if you also swap blue and yellow. If you find a shift around which everything is symmetric, then there's not going to be a way of telling. Yeah, yeah. If they feel different, you mean if one makes you feel alarmed and the other makes you feel calm or something like that? I agree and that really is worth thinking about. But what I was suggesting is that I don't actually have a red card, but let's take the dear old fire truck. Suppose you see the fire truck. Then you associate that color with blood and fire. Yeah? And the other guy is looking at it and seeing this, right? But they associate this color, this sensation, with blood and fire. Yeah? So if you feel alarmed or there's some kind of arousal when you look at the red, then they're going to get that kind of arousal when they get this sensation. Because when they cut themselves, that's what they get. You see what I mean? When they get fired, that's what they get. But these are the natural lines of thought to test that. OK? Yes? OK, let's call it x, right? x cycles per second, something like that. Right, OK. Very good. Yes, yes. Well, that's a natural reaction. You might think they've got to be different. Yeah, suppose they are different biologically. The sensations are still just the same. I mean, sorry, what I mean is the sensations are around the other way. That's what I mean, yeah. That's one possibility, yeah? The question at really in the back here is, how would you know? You see what I mean? Maybe the sameness of the biology does guarantee sameness of sensation. But maybe it doesn't. How could you tell? Yeah, yeah. Read dreams, yes. Yeah. Ah, that was all right until the very last thing, right, which visual experience. That's the question, right? How could you do that? The same sensation that every single person said. But how could that, how could checking the brain before you do the experiment tell you which of these qualia the person was having? That's the issue. Oh, I see, you just mean that as a comment, yeah, yeah. That's fine. And I love the idea of the machine that can read your dreams. There you are, sound asleep, and there's a TV screen with your current dream on it, yeah. Yeah, no, that's just great, yeah. OK, so let's just, I mean, in a way, this is already arresting enough. But let's think about what it means for functionalism. And so I want to backtrack here and go over how we got to functionalism and then say something about what this means for functionalism. So the next few things I say is really important that you should find everything I just say extremely obvious. I hope it's going to seem like I'm just laboring the obvious at this point. So stop me if anything doesn't seem completely obvious. So remember we started out with dualism and the idea there's two kinds of stuff, mental stuff and physical stuff. Stuff made of atoms and some other kind of ghostly stuff made of ectoplasm. And I said the argument against that kind of picture is it's really difficult to see how the atoms can be making a mind. That's really hard. But you don't help by moving to ectoplasm because whatever ectoplasm is, it's really hard to see how that could be generating a mind too, yeah. Just postulating a different kind of stuff doesn't help. And we had that example of the TV where people say, well, the way TVs work is they're made of TV stuff. And that's not a way of explaining how a TV works because if you found it difficult to explain how electricity could be making a TV, you're also going to find it difficult to see how TV stuff, whatever that is, could be making a TV. You just made things harder, not easier, by saying it's a different kind of stuff. So we have to work with a basic problem. How can biology, how can physics be generating a mind? That's OK. That's plain as day. OK. So then we say, OK, that was the wrong way to think about it. We should think of having a mind of being intelligent as a matter of behaving in lots of particular complex ways, as what the behaviorist said, that mental states, having mental states, having a mind is just a matter of being disposed to behave appropriately. And then the problem about the Superspartons was you could have sensations like pain, even though there wasn't any specific connection to displays of behavior. Yep. A Supersparton after centuries of breeding and so on could have their pain sensations disconnected from outward behavior. Yeah. That's OK. And then we say, OK, look, this is about behavior. It's actually the brain that matters for having a mind. To have pains is just to have a particular kind of biological structure in your brain is to have C-fibers or whatever. And then there's that problem about variable realizability. It's obviously possible that just as you could make a conductor out of lots of different kinds of stuff, you could make a mind out of lots of different kinds of stuff. Octopuses surely have minds, but they're made out of quite different stuff. Yeah, that's OK, too. That's plain as day. OK. And so that's how we get to functionalism. We say it's not the brain state itself that matters. It's the functional role. It's not whether you have C-fibers. It's whether you have a bit of biology that works in your brain the way that C-fibers do in ours. So it's that you've got something that's doing this work in the overall structure. Just as being a switch doesn't demand that you be made of copper and Bakelite, you can make a switch out of lots of different kinds of stuff. It's still a physical thing. Any switch is just a physical thing. But what makes it a switch is the role it plays in the overall circuit. So similarly, what makes a brain state a realiser of pain is the work that it does in the overall system, its functional role, what causes it, and what it does. And the argument to this point really seems compelling. Functionalism must be right. And as I said, it really is science's philosophy of mind. It is the way scientists think about the brain and the mind. Yeah? I don't know. OK. OK, it's really important this should be plain as day. You see how compelling the case is for functionalism here. It's got to be true. It's the only game in town. So if functionalism's right, then we're going to describe functional role, the functional role of any state. We can do that quite abstractly. If we're going to describe the functional role of a particular state, S2, we give a big list of all the outputs to that state and a big list of all the inputs to that state. And then we give a big list of, for each input, what state you get next and what output you get. And that's all there is to say schematically about the functional role of a state. So what makes a particular brain state or a particular state of whatever kind of structure an organism has? A pain or a sensation of red is just its functional role. What outputs you get for what inputs? Right? That's all right. So then what is it to have a red sensation in this view? What is it to have a red quali? Well, what it is to have a red quali is to be in a particular machine table state. That is a state like S2, a state like that. So you describe what a red sensation is by saying, well, it's the kind of sensation that is caused by blood or fire or fire trucks. It's the kind of sensation that has stop lights as its cause. It has the kind of sensation that has saying that's a red one as output. Yeah, that's what it is for something to be a red sensation. So functionalism says to have a red sensation is to be in a particular machine table state, S2, for example. And as I say, the argument for this view is really compelling. It can't be anything else. That's what science works with that idea, because what else could having a red sensation be? Having a red sensation is variably realizable. An octopus could have red sensations, even if his visual system is quite different to ours. So all it can be to have red sensations is to have a particular place, to have a structure that's got a particular place in the overall circuit. But what we've just been seen through looking at these cases of spectrum inversion is that you and I could both be in the same functional state, even though your spectrum is an inversion of mine. You and I could be functionally identical. We could be all wired up in just the same ways with just the same structure. But what you get when you look at the Campanile is that scene. What I get when I look at the Campanile is this scene. We are going to be functionally identical. We give the same outputs for the same inputs. But our sensations, as you can see, are radically different. There's nothing in common at all between our color sensations. So functionalism must be wrong. Yes, could we apply that to emotions like pain? Yeah, it's harder with pain. It's easier with color. I don't think it's completely impossible with pain. But the thing is pain seems to have distinctive connections to behavior. I mean, if you're pain-sensitive, how should I put this? Pain sensations don't really structure themselves with your other sensations the way that colors do. Colors have this nice structure that can be mapped onto itself, if you see what I mean. Whereas pain and pleasure, for example, don't really map onto one another. But at a more abstract level, once you've got the idea here that the functional structure is one thing and what the feel of the sensation is quite different, then it's just a perfectly natural idea, even though you can't spell it out in quite as precise a way for pain, that maybe what you feel when you feel the pain is functionally just like mine, but the feel is actually quite different. Couldn't that be? Yeah, it's a very natural thought. Yeah? Yes? That's right. Yeah. That's right. Yes, right, right, right. Yeah, the peaceful scenes and so on. Yeah, I think that's exactly right. And the only thing I'd add to that is when I talk about the qualia or the feeling you get when you look at the scene, the sensation of color, I don't just mean the associated emotions and so on. I do mean that, too. But I also mean just, I don't quite know how to put this, but the blueness itself, the color sensation itself that you're then associating with all these other things. You see what I mean? The intrinsic, the specifically color bit of the overall experience. Now that's completely different between here and here, right? The specifically color bit. And your point is you could have quite different specifically color bits, but the same associations and feelings, is that what you're saying? Yeah, yeah. Or vice versa. Exactly, yeah. I just completely agree with that. Yep. Yep. So this is a critical thing. Yeah, this is the key point about spectrum inversion. Yeah. The picture isn't a brain state. Sure. Yeah. It's a trigger, all right. But I agree that the picture is just a trigger. Sure. OK, I think I see. But you have to separate these things very carefully here. This is why I went through the history so far. This is causing a brain state. That's all right. But the question is, what makes the brain state a realizer of one sensation rather than another? And it's important to be very pedantic and careful here about when you're talking about the brain and when you're talking about the sensation, yeah? The point is you could be, someone could be, you have one set of sensations generated in you by this picture, right? I don't know what they are, yeah? Now, this picture could be generating quite different sensations in you than in me. But functionally, we're going to be exactly the same. So sameness of functional architecture can't be enough for sameness of sensation. That's the argument. Different. Yeah, that's true, but it's not relevant, because we're not talking about brain state here. We're just talking about the sensation. Yeah? Yes. I do think you were saying you could bring it about that we have the same experiences, yeah? So if ordinarily, your experiences are inversions of mine, I could say, I could be saying, I wish you could see what I see when I look at the Campanile, and then I do that thing. And I say, no, there you go, all right, right. Now, that's fine. The thing I want to get at though is something that you're actually taking for granted there, that you and I could be organized in just the same way, even though our sensations were quite different, yeah? And the reason that's so important is that the point we got to when we were thinking about variable realizability and the octopus and all that was that which particular brain states you're having isn't important for whether you have a mind or what kind of mind you have is how your brain is wired up, how your brain is organized. That's got to be what it is to have a mind. But this is telling you that that can't be right, yeah? See, the stakes are pretty high here. If this really makes sense, the spectrum inversion, then functionalism is just not correct. And it's not that there's something subtle or hard to understand about the way it's not correct. It's radically incorrect. Functionalism is telling you that this experience is just the same as that experience. And that is a lie. Yeah, it doesn't matter. Who can't, well, that's actually a good functionalist response. Spell that out a bit. It doesn't matter. Yeah, that really is good. Can you say a bit more about why it doesn't matter? Yes, settle down, yeah. OK, that's a really important point. And I'm going to say some stuff about it. But I don't mean that what I'm about to say makes it go away. If you see what I mean, that's an important reaction. Because from a practical point of view, for negotiating with other people, functionalism is just right that it's identifying how you push someone's buttons, how they're going to push your buttons. And everything about that is captured, everything, you might say, of practical importance is captured by functionalism. So even if there is a difference here, who cares? That's a way of playing back to you what you just said. Well, there's a very general abstract point here. Sometimes we really care about a difference, even though we can't tell whether that situation is there or not. Look, here's one scenario. While you're at Cal, you develop a group of friends. And you take them with you, you all keep together. You keep connected into adult life. You are respected and admired by all of them. And they keep with you through your various career accomplishments until you are in a happy and contented old age. Here is another scenario. While you're at Cal, you have a group of people who decide that you're just about the daftest thing they have ever seen. And they like to make fun of you. So they pretend to be your friends. They pretend to admire you greatly. They tell each other stories about you while you're not there. And they enjoy this so much, they keep it up through all your life. Now, can you tell the difference between these two scenarios? No, you can't. I mean, they're really good, let's suppose. Does it matter? Well, call me insecure. To me, that kind of thing matters a great deal. So the general point there is a distinction can matter a lot, even if you can't tell on which side of the distinction you are. If another person, suppose another person doesn't feel pain, they're just a zombie. They've got the functional structure of something that feels pain, but they don't have any sensations. So you go to great lengths to keep them safe from harm and so on, but it doesn't matter, right? I mean, what I mean is because they don't have any pain. This is just a zombie. Why would you care about a mere mechanical zombie? So whether this thing has pain or not can matter, even though you can't tell whether it has pain or not. Yeah, if it has all the functional structure, but minus the pain. And similarly, knowing what it's like in someone else's mind really matters to us. If you meet someone you haven't seen for a while and you say, how are you? What you want to know is, what's it like in there? So that's what you care about. And if you're told, well, what is like in there is absolutely unimaginably alien. This is just the tip of the iceberg. What's going on in someone else's mental life is completely alien to anything you could ever imagine. Well, oops, oh no. Then that really seems important. Oh, god, OK, sorry for me, right? OK, anyone? Control and scrolling down? Well, well, I think we're going to have a short technical break while I switch this off. Oh, well, it was fun while I lost it, all right. Well, yeah, the trouble is with this one, you can't tell the difference. OK, so yeah, what is like in your point was, what is like in someone else's mental life if that doesn't make a difference to our functional structure than who cares? And my point back is sometimes we do really care about stuff. It can be the most important thing in the world, even though you can't tell on which side of a distinction you are. This is going to be where it opens up in exactly the same state, but OK. Another victory for the human over the machine intelligence. So the thing that seems so engaging about the mind, the thing that is so puzzling is actually this stuff about sensation? Oh, no, what have I? Oh, bliss, right. OK, so that's really the key thing. Functionalism is missing out an aspect of our color experiences, the aspect that's different between you and me in that scenario. So is that absolutely plain up to this point? Yeah? Yeah? It's a real hard problem for functionalism because it seems to be missing out the thing about the mental life that we care about so much. And remember last time we were talking about Bloch's robot, this thing with billions of people in it moving about. That's functionally just like you. But if you give it a Chinese burn, does it have the qualia? Does it have the qualia if you give it the Chinese burn? Let's take it from the top. OK, let's remember where we got to last time. So we've got a billion people all phoning each other and so on, driving about a robot. And it's functionally structured just like you. OK, the whole thing is functionally structured just like you. So if you do that thing to the arm of the robot, back in the network of a billion people, they're all phoning each other. They're all moving the limbs and so on and saying, stop it, stop it, and so on, right? But does that whole thing, that whole system, have the feeling that you get when someone gives you a Chinese burn? Put up your hand if you think the answer is no. Put up your hand if you think the answer is yes. Put up your hand if you have no idea what I'm talking about. I'm sorry, what were you going to put your hand? OK, yeah, if you don't know, OK, that's fair enough. As long as you know what the question is, that's all I ask. Right, yeah, I mean whether the whole structure, the whole network, the whole corporation has a single thing, that feeling. No, I don't mean the might. Well, you can put it like that. There's a way of asking, does that whole thing have a mind? I mean, can you make sense of talking about the Apple corporation having a mind? Could the whole Apple corporation feel an awy? Block said, that makes no sense. Yeah? It could have the functional structure of a human being, but it still doesn't feel an awy. It doesn't get that sharp pang. No, what does? Remember, the robots just is the billion people driving about an empty shell. That's right, they're controlling it. OK, well, that's a view, right? Block said the shell itself isn't a person, doesn't feel pen. I mean, it's just a simple robot. It really is an empty husk. Yes, OK. All right, I'm not trying to knock that over. I just want to remind you that Block's idea was that there isn't any such level. Yep, yep, yes. I completely agree, yeah. Yeah, yes, yes. I think that's right. I actually do think that's right. There is a question of whether Block's thing is right at all, just because the humans can all get together. Incidentally, Jackson, do you want to comment on this? It's up to you. If you have a sound bite, you'd like to share, but that's great. Yeah, that picks up on the last question. Yeah, yeah, yeah. Yeah. I agree, yeah. OK, OK, right. OK, at the moment, it's not really that I want to settle the question there. You see what the structure is of Block's argument, whether you buy it or not. The structure was, I get something here that has got all these S1, S2 states just the same way a regular human has, but it doesn't feel anything at all. It doesn't have any qualia. That was Block's idea. Yeah, that was one objection to functionalism. So that's an absent qualia objection to functionalism. You have the right functional states all right, but you don't get any qualia at all. And this inverted spectrum argument is saying you could have the same functional structure and you get qualia both times, but the qualia are all different. So this is an inverted qualia challenge to functionalism. This is just a quick way to remember these objections. Inverted qualia versus absent qualia. Does that make sense? That'd be determinology. If you've stayed on the bus this far, that's pretty good. Is that makes perfect sense? Exactly. Absent qualia is a Blockhead argument. You have the right functional structure, but the qualia just aren't there. OK. OK, so if you're a good functionalist, how might you try and reply to this? I think the challenge, but it doesn't make any difference, is already an interesting response. Another kind of challenge is, does this scenario really make sense? I mean, there are comparisons among people's psychological states that at first sight seem to make sense, but they don't really. I mean, suppose that you and I are going to watch a TV program and the choices, let's say, are we going to watch, what's on TV? Are we going to watch? Sorry? Breaking Bad. Right. Are we going to watch Breaking Bad or are we going to watch Mad Men? That's OK. Right. And you say, OK, I really want to watch Breaking Bad. And I say, well, I don't really mind whether we watch Breaking Bad or Mad Men. I have a slight preference for Mad Men. It's a slight preference. And you say, I just can't stand Mad Men. It makes my skin creep. But I can't wait to see what is going on in Breaking Bad. And I say, well, that's fine. Your relative preference is for Breaking Bad over Mad Men. I have a slight preference for Mad Men over Breaking Bad. But what we now have to factor in is that all, absolutely all of my desires are of titanic magnitude. I am a kind of passionate volcano in my desires, whereas your tepid preferences don't really stack up too much, so that even the largest gap between any two of your preferences is smaller than the smallest difference between two of my massive passions. Right? That makes sense, right? Well, I mean, what I mean is you kind of understand that emotionally. That's kind of recognizable. But the thing is, it really doesn't make any sense. If you take two people's preference structure, what they prefer to what, you can rank them. It's like relative space and absolute space. You can say relatively where everyone's preferences are, respect, what they've liked most, what they like least, and so on. And you can say relatively, there's a structure of my preferences, what I like most and what I like least. But saying that my preferences have some kind of absolute value, like voltage or something, that they could really have an absolute value of being bigger or smaller than your preferences makes no sense, right? I mean, that's really the rational reaction to that situation. It doesn't make any sense. You can look at the structure of my preferences. You can look at the structure of your preferences. But asking whether mine are absolutely bigger or smaller than yours, that's just crazy. It's a best kind of emotional expression of egomeria or something, yeah? But it really makes no sense. Do you see what I mean? Can you articulate that? I don't necessarily agree with that. Half that compared to something else. Yeah, right, compared to another of their preferences. Yeah, so the thing is, what I mean to be saying is, if you take my preferences, yeah, you can look at their structure and say, if you've got a preference for coffee, and I've got, so how much you like coffee? How much you like coffee here? And you say, I like tea much less than coffee. I say I like tea. You say I like tea much more than coffee, something like that. You could rank your tea coffee preferences with respect to one another. And you can compare that to mine, yeah? So I just agree with that, yeah? So this is kind of relative measuring, yeah? But what I mean to say makes no sense is saying, the absolute value, this just gets a 10 for you. Whereas for me, it's 10 to the 6, right? These numbers make no sense. Yeah, all you've got is the ordering of the preference with respect to one another. You see what I mean? Is that more persuasive? Okay, good, yeah, yeah, yeah. Sorry, yeah. Oh, okay, yep. I'm saying that makes no sense, yeah. I'm saying you can make sense of just the structure of preferences and where my preferences are with respect to one another, and where you are with respect to one another. But looking at absolute values like that just doesn't make any sense, yep. I agree there's something to that. What are you gonna do about it? How much do you do about anything? Yeah, I think all you can do there is, all you're doing there is ranking, how much do you prefer getting water to staying where you are? You see what I mean? There's how much you like just sitting about, how much I like sitting about, and I might like it much more than you do. You see what I mean? And so you say, well, you're very apathetic, but really what you're doing there is measuring all your preferences with respect to my baseline, with that baseline, and measuring all my preferences with respect to that baseline. You see what I mean? Yeah, yep. Yes, I do, yeah. I really like that. Right, that's right. But you could do that, give them numbers, and you could give them all the same number, yeah. But really, that's a good way of making my point. The only significance the numbers have there when you're giving numbers to all your preferences is by way of comparing them to one another, ranking them with respect to one another. So you could have them all coming out five, but that's just a way of saying they're all equal, yeah. Right, yeah, that's right. My point here is you're always making a comparison, yeah. And what would make no sense would be to say, all your desires get values in the range one to 10, whereas all my desires get values in the range one to 10 to the 23, yeah. No, 10 to the 22, 10 to the 23, right? I know you can compare mine to yours like that. That makes no sense. For a moment, you might think that made sense, right? If you were having an argument about the TV or something, but really it makes no sense. Look, let me just give another quick couple of examples of comparisons across people that, of course, you might think they make sense, but then you think about it and they don't actually make sense. If you wear spectacles, you know that sometimes when you're in a new pair of spectacles, things look smaller. Yeah, sometimes you put them on and they look smaller, and then after a bit, somehow that effect goes away. You know what I mean, yeah? And it's not that they don't look sharp or something, they just look smaller. And then it's kind of puzzling to know what that is, that effect. But suppose you go to the optician and they're doing sight tests on you, and they say, your vision is great, your vision is 2020, your acuity is just fine, and how big an area you can see at a glance is just the same as a regular person's. But you have a very rare deficiency. You see everything smaller than other people do. Well, but we have this expensive treatment that will put you right. I mean, that makes no sense, right? You can't be seeing everything smaller than other people, can you? I mean, sometimes you can see something smaller than the look before, but you can't be seeing things smaller than everybody else. Or could it be that you see everything tilted everybody else sees an upright thing upright, but you see everything tilted? That makes no sense, right? Well, what does tilted mean? I mean, this is upright, right? You get a pole on the ground, you say that's upright. Tilted is defined by comparison to upright. Yeah? How could you be seeing everything? I mean, you do get... People sometimes say, well, when they find out how the retina works, they say knowledgeably, well, you know, everybody sees everything upside down. I mean, that is a crazy view, right? Everybody does not see everything upside down, but finding out that thing about your retina does not show that you see things upside down. I mean, there was this case of people being fitted with inverting prisms, right? So when you put on the inverting prisms, you see everything upside down, and for the first few days you're wearing it, the first few hours you're wearing them, that's really confusing, right? You bang into things you can't navigate properly. After a remarkably short time, after a couple of days, people who are wearing inverting prisms can navigate around just fine. They get around just fine. One guy wearing the inverting prisms in the original experiment back in the 1920s, used to drive his motorbike around the streets of Innsbruck, wearing these inverting prisms. Now, if you're seeing everything upside down, you can't be getting everything right like that. You just... I mean, there are two hypotheses. One is vision has flipped round. The other is that you're still seeing everything upside down, but you just adjusted to it. And what I want to say about that is the functionalist is surely right about this kind of case. If you're functionally working just like everybody else, then you just do see everything the right way around. That's all it is to see everything the right way around. It makes no sense to suppose that you're seeing things tilted if you're functionally just the same as everybody else. Which is an argument against spectrum inversion. Exactly. So, okay, you're ahead of me. So, if you think about the spectrum inversion, then isn't that like these cases in that... What you're trying to do is say there's the way your colors are ordered with respect to one another. There's the way your color perceptions are ordered with respect to one another. There's the way my color perceptions are ordered with respect to one another. And you're trying to suppose that absolutely there's a difference between them. But maybe that makes no sense. Maybe the functionalist is right about that. The functionalist is going to say, well, one thing a functionalist might say is that comparison between your color experiences and mine is like trying to compare the size of your desires in mine. It seems that first to make sense, but it doesn't really. All you can make sense of is the structure of the color space. In color perception, you only get structure. You don't get absolute values for the colors. Yes. Sure, I completely agree that can happen. That's a less radical case than the case I'm trying to consider. The case I was trying to consider was one. Not where you just get taken in for a moment, but where absolutely everything in my visual field is tilted from birth to death. I just see everything at a bit of a slant. I get around the same way as everyone else. I drive a car just the same way as everyone else. But it never shows up. But little did I know it. It was always skew, right? I just struggled with that my whole lot. Yeah, that I think makes no sense. Your case really does make sense, that visual illusion kind of case. Okay, quickly, one, two, three. Could you make this for everyone else? That's right. Well, another way of putting that would be to say you don't know what tilted means here. How could you compare, yeah? Tilted is by comparison to some standard, and the only standard is inside your head. There was someone else, yeah, yeah. Yes. Okay, I don't know, that's fair enough. You see the argument I'm trying to make here. Yeah, okay, that's what I really care about right now. But I agree the feel of it is different in the color case. But if you could make out that all it is to color, perception of color, color experience is getting that structure, then that really would give the functionalist something good to say here. Yeah, it's just an illusion that there'd be absolute differences in color between you and me. Yeah. Okay, we'll come back to that. Yeah, yep. That really is true. And in the same way of preferences, they're all a bit different. Preferences are all modulated somewhat differently. Yeah, what you care about. But that kind of modulation in color perception between people, and I agree that or vision generally in people, I agree that it's there, you know, what leaps out at you. If you or I look out at the room, then who leaps out at you and so on will be different. Yeah. But those things you can pick up functionally, those really are going to be a matter of the structure of your visual experience as opposed to the structure of my visual experience. Yeah, well, this one leaps out at you more than that one does. Do you see what I mean? So that's a comparison that's kind of internal to your own color experience, to your own visual experience. Or if you just have bad eyesight, yeah. Okay, I agree. That's a comparison across people. Yeah, if you have bad eyesight, that's relative to a standard set by other people, so that really is right. But that's completely functionally pick-up-able, yeah. I mean, that's what eyesight tests are for, yeah. You spot it in a flash and someone's got bad eyesight. Yeah. Yeah, yes. That too is true, yeah. But it's still a matter of comparison across us. If you spit, what you're pointing out to there is something about variable realizability. You could be having the same experiences because of different physical things, yeah. But the functionalists will be fine with that. Okay. The thing about that is, someone said it feels different in the color case. I think if you think about that idea of waking up and the fire truck looks different, that's really pretty powerful, yeah. I mean, you can imagine that. That seems clearly possible, right? That scenario where you just walk up and it's changed from looking like that to looking like this. And then you say, well, if I could wake, you could wake up and there could be that change, but that's the idea of waking up with that change. All my desires are no much stronger than they used to be or my vision now is tilted or upside down. That doesn't seem to make sense so much. And here's another way of putting it. This is due to Gilbert Harmon and Ned Block. This is Earth, right? This is the planet Earth. Consider for a moment, inverted Earth. This is an actual photograph of inverted Earth. It is far away in a distant galaxy. And as you can see, it's very similar to our Earth with one difference. Can you guess what the difference is class? No, that is the wrong answer. I mean, there are aliens there, but the aliens are in many ways just like us. They're not quite. The big difference is all the colors actually are inverted. I don't know if you can tell by looking at the photo. Yeah? That's why this is inverted Earth. Right. Boy. Hello. Right. That's for technical reasons we're not going to go into right here. But you can see, I mean, this is very rare. This is an actual snapshot of inverted Earth from our traveling satellite. Yeah? So as you can see, the colors are quite different. In fact, they're inversions of all the colors we get on Earth. Now, there's nothing weird about that supposition, right? I mean, I don't say it's likely, but there could perfectly well be a planet in a different solar system. There was just like ours, same size, same shape, same shape continents, except the ocean is a different color. All the land masses are a different color. The trees are different colors. They've got fire trucks there, but the fire trucks are different colors. They've got people there, but the people are all different colors to the people here. I mean, they've got humans there, but the humans are all different colors to the humans here. Right? Okay, so give me that. That's all right. That makes perfect sense. Yeah? Now, suppose, here's a further supposition. Okay, so all the people there are, except for color and color vision, they're regular humans and they all talk English. And the thing about them there is they can look at their trees that are different colors to the trees on Earth, but they say those trees are green. They look at their fire trucks, which are some kind of wild different colors to ours, but they apply the word red to them. Okay? That's okay? They apply the word blue to their sky, even though it's a different color. Now, here's another supposition. Suppose that you have, suppose that you're on Earth and the scientists on Earth have developed color-inverting goggles, right? So you put on the goggles and everything looks around the other way. I don't really have the technical terminology to explain exactly how this is done, but it's just like what I did with pushing the keys, right? You put on the goggles, everything flips around in color. It's like you're looking at a color negative. No, no, you're not inverted Earth yet, right? I'm just saying you could clearly have such goggles, right? The invert around the colors. So now you're shipped to inverted Earth and on the way, you're given color-inverting goggles. Now, when you land on inverted Earth, wearing your goggles, what is it going to look like? It's just going to look the same as the place you left, right? If you're kidnapped and shoved off there and given the inverting goggles, you're giving them contact lenses or something, you're giving them in a way that you can't really tell you're wearing them. You might not even realize you'd shifted planet, right? Yeah? But when you get to inverted Earth, are you going to talk the same way as everybody else? Yes, they apply the word green to the trees and so on, yeah? So you're going to talk the same way as everybody else, but are your color sensations the same as their color sensations? As far as you know, right? But they are just biologically like you and me living in a world where everything is really round the other way, yeah? They're biologically just... Let's suppose that they are actually... The twin Earth was actually seeded from Earth's stock with humans, yeah? So they're just humans looking at this, yeah? So their sensations are round the other way to yours or mine, yeah? Because they're looking at us round the other way to yours or mine. But when you get there, wearing the goggles, everything's going to look just the same to you as it did on Earth. You're going to talk the same way as all these people, but your sensations are quite different to theirs. Even though you're functionally just like them... I'm sorry, there's only... OK, quickly, but there's only a couple of minutes left, yeah? They still have the same sensation to the color as you? No, because they're biologically just like you without the color-inverting spectacles. Yeah, they're just... They're just humans, really. They are seeing something red, something that really is red. And they've got exactly the same kind of color vision as an ordinary Earth human. So it's going to look red to them, yeah? They just use the word green for that, yeah? So you talk the same way as they do, but your color sensations are quite different to them. Now, I just finally want to look at... Quickly look at Nida Rumilan's point. So far, we've been looking at a lot of thought experiments, but consider this. The red-green color blindness is relatively common, right? There are probably some red-green color blind people in this room. Now, there are two ways of being red-green color blind. In the eye, there are... Color vision depends on three cone types with different kinds of pigment in them that make them sensitive to a light of different wavelengths, yeah? So you've got these three types of photopigment, B, G and R, and what happens in red-green color blindness in one variety? The pigment that is usually in the green cone is also being used in the red cone, so you don't get discrimination here. And in other types of red-green color blindness, the pigment that is usually figuring in the R-con is also figuring in the G-con. So again, you don't get red-green discrimination, yeah? So these are two different types of red-green color blindness and they're both relatively common. That's okay, yeah? So what's going on in one kind of red-green color blindness is that either the pigment that's normally in the G-con is also in the R-con, or the pigment that's normal in the R-con is also in the G-con. So red-green color blindness like this is very easy to detect, right? People are usually picked up with this at school in testing. Yeah, I mean early in school in testing. Okay, but now just statistically, you've got a certain proportion of the population with the pigment that's usually in the G-con, also in the R-con. You've got another proportion of the population that's usually in the R-con, the pigment that's usually in the R-con is in the G-con. So statistically, there should be a number of people that are both types of red-green color blindness. That's to say, you can just read off from the statistics. There are going to be a certain amount of people who have the pigment that's usually in the R-con in the G-con and the pigment that's usually in the G-con in the R-con. So the pigments have been swapped around from the two types of cons, right? Does that make sense? Okay, now, so the ratio in males should be about 14 for every 10,000, right? But no example of this kind of color blindness has ever been detected. Now, how could you detect it, right? Because what's going on is that this person is getting red stuff where there should be green, green stuff, where there are red. You know why it's not going to be detected. They're going to be functionally, highly similar to you or me, right? So this is a real case. I'm sorry, I can't take anything right now because we're nearly on time. So this is not made up, right? This is really what is happening. This is the stats, 14 in 10,000. That's quite a lot, right? That should be picked up if it was possible to pick it up. But we know, if you just think about it, it's not going to be possible to pick it up. So these people are going to be real cases of spectrum inversion in amongst us. So if you're male right now, I can't use, if you're male right now, then the question for you is, how do you know it isn't you? You could be one of the 14 in 10,000. And on that bombshell, we have to stop. Okay, now you go on the unity of consciousness next time.