 Hey, good morning. Let's start. So today is Brains and Avat. Putnam's article, Brains and Avat. And the question, how do you know that the causes of your experience are what you take them to be? This is the classical philosophical problem of skepticism and it really illustrates the general model that if you get the stuff that we've been talking about, about the theory of meaning, about the theory of reference, if you get that stuff right then classical philosophical problems are dealt with very rapidly. So it's actually a fairly straightforward to address skepticism given the material we've had already. We're going to begin with another basic question. There's really going to frame a lot of what we do in the next three weeks or so, which is reductionism about meaning, explaining what meaning is in terms that don't presuppose meaning, explaining how meaning can be part of the natural world because we've already actually already made quite a lot of progress with that. Twin Earth cases are really very powerful for thinking about these issues. I just want to try and bring that up. So right back at the very first lecture in this class I was talking about the question, what makes it so that words have meaning? There's one world, there's a physical world, there's nothing in it but lots of atoms and so on governed by physical laws. How does it come about in such a world that the signs have meaning? How does it come about that the words refer to objects? And surely the facts about meaning can't be primitive, the facts about meaning can't be irreducible facts about the world. They must be explainable in terms of more basic facts. And we must be able to say how this phenomenon is happening, that there are sentences that are getting it right or wrong, that there is reference to objects. And if you say well, of course words have meaning because we associate mental images with them, or words have meaning because we give them meaning, our culture, our psychologies give them meaning. Find that breathes life into language. That's a very natural idea and it's anyone's first reaction I think to the question. But it really doesn't help because if you raise the question well, I can refer to the tree because I've got a mental image of a tree, then the next question is how come your mental image is referring to the tree? How come you're able to think about the tree and you just shuffle the problem one stage back if you appeal to the mind here? This is Putnam. Thought, words and mental pictures do not intrinsically represent what they're about. Just to say, if you say well, the word tree has the meaning it does because I associate a concept with it, some kind of word that runs through my head. Well, how come that word that runs through your head stands for a tree? What's going on there? How did that happen? And similarly for mental pictures. When you get that straight, you realize that you can't identify, you can't explain concepts in terms of any kind of mental object because a concept is supposed to be something that intrinsically refers to an object, but nothing that's running through your head intrinsically refers to an object. There's got to be some way of explaining how this thing got connected up to the world. Well, you might be a kind of dualist here and say, well, maybe it's kind of an exaggeration to say there's one world and it's a physical world. Maybe you might say, well, there are facts about meaning and reference, but everything is what it is and not another thing. You can't explain meaning and reference in terms of anything else. But we really do want to understand how should I say, it's not magic that this happens. Surely we can explain how a world that entirely consists of whirling collections of molecules can have meaning and understanding in it. And the two questions here are, as we've framed it so far, how is it that one part of the natural world can be about another? And how does it come about that there are standards of right and wrong in the natural world? So that's just to frame the question that we'll be looking at in the next three weeks or so. Is it clear what the question is? Not really. What part of, we have to explain how meaning and understanding can be part of the natural world, what part of that don't you understand? Oh, you do get that part. Oh, okay. Does everyone get that part? Okay. That's all I'm trying to get over. So is there something else? Well, to explain how it isn't a world that's completely described by physics, in some sense physics gives you a complete description of the world. If you said, you might say the world has many mansions. You see what I mean? You might say, well, there's a realm of meaning. There's a realm of moral values. There's a realm of thoughts and sensations. And I don't have any puzzle about how these are all related. The trouble is we do seem to think that they're all related. So natural is really, natural is something of the implication of the world is described by the natural sciences. What could be planar than that? You guys? Is there anything planar than that? Okay. I mean, yeah, good. Yeah, that's another way to put the same thing. Right and wrong, in some sense, that's normative, right? You ought to say the right thing, you ought not to say the wrong thing. Something like that. Truth and falsity aren't. It's not like, I mean, positive charge and negative charge. Right, sometimes you get a distinction that has no value to it. I mean, some electrical charges are positive, some are negative. It's not that the positive is better than negative. It's just a joke if you say you're into the negative circuits, you really ought to try to be more positive. Yes, you see what I mean? Or if a magnet has two poles, that's just a matter of indifference. Truth and falsity are not like that. When you form a belief, you're trying to get things right. When you make a statement, you're representing yourself as saying what's true. So we aim at truth in a way we don't aim at falsity and that seems to be part of what truth is, is what you aim at in belief and assertion. But where did that come from? How did that happen? If the world is just described by physics, then how can right and wrong have come in? I'm not sure if I need to keep explaining this sort of, are you feeling reasonably comfortable with that? Okay, now this looks like a hard question, but Twin Earth cases really make it seem like we're on the way already to addressing this. Remember the Twin Earth scenario? So you get Earth with Oscar I, you get Twin Earth with Oscar II, and the two Oscars have the same physical states, but they're in different physical surroundings in the two planets. So the world's the use of different meanings. That's right, that's all right. Remember the Twin Earth cases? We are old stuff, yeah. Okay, so that means, if that's right, that means you can do a factoring here. You can factor Oscar I and Oscar II's understanding of the words they are using into the bit that's inside the head and the bit that's outside their head. The bit that's inside the head isn't enough to constitute understanding or meaning because Oscar I and Oscar II share that, but they nonetheless assign different meanings to the signs. So the bit that's inside the head doesn't constitute meaning on its own. So there's got to be a second element, the bit that's different between Oscar I and Oscar II, that's the bit that's outside their head, yes? Are you following me in the kind of arithmetic here? There are two bits, stop me if this gets too technical. There are two bits, there's a bit inside the head and a bit outside the head. Neither of them on their own are going to be enough for meaning because what's inside your head doesn't give you enough for meaning. What's outside your head doesn't give you enough for meaning, but stick them together and then you've got meaning, yes? That's all right. So that shows you how you can start to analyse what understanding and meaning come to because you can look separately at the bit inside the head and the bit outside the head. So you can analyse meaning in terms of these two elements, the bit inside and there's something that's presumably causal or contextual or something like that, something about what kind of environment you're in and how you're interacting with it, there is a bit outside the head. So we're on the way already just by thinking about twin earth cases to analysing meaning and understanding. It is a question putting and set up twin earth for water and names for natural kinds generally. So you might wonder, well, can you really generalise this? I mean, how far does it go? So we're going to try, just take my word for it, we are going to try this analysing meaning in terms of these two components, the bit inside the head and the bit outside. But there's a question how far you can take this because there's a question how far does the reach of twin earth cases go? And you're going to have twin earth cases for water, you're going to have twin earth cases for tigers. What about terms referring to individual objects? Names like Gödel, terms like that cup. Can you have twin earth cases for them? What do you think? Yes, yes of course you can. Yes? I mean here I'm on earth, here's my double in twin earth. We both use the name Gödel, but we're referring to different people. Yes? Okay, what about artefacts like kettle or automobile? Yeah, earth automobiles look very like twin earth automobiles, but in twin earth they're plants. They're mobile plants. Yeah, they grow in greenhouses. Yeah, that could happen. Couldn't it? That could happen, very good. Look kettles, well they could be plants too. Exactly, that's right. And they might be alive, the twin earth kettles might talk. I mean we wouldn't be able to hear them if you see what I mean, but they might talk to each other or to the teapot. You see what I mean? You can imagine them being quite different in earth than in twin earth. What about colours or shapes? We talked about that a little bit, colours? The colours all look just the same in twin earth, but not really the same. Yes, if you've got locks kind of picture that could happen. Different kind of spectral reflectances, different physics producing the colour appearances. That's right, physics is the same everywhere. What I mean is those colour appearances in twin earth are caused by different physical characteristics of the object. You see what I mean, the basic physical laws are just the same, but it's just that the kinds of light reflectances you get in twin earth are different to the kinds of light reflectances you get on earth. The upshot for us in our inner life is just the same. So it can go quite far, right? The possibility of twin earth cases. What about social relations? What about friendship and love? Could it be different in earth? It's just the same in earth and in twin earth, but the real thing you're talking about is actually quite different. On earth, love has to do with what goes on in your amygdala. On our twin earth, love has to do with what goes on in your frontal cortex. Yeah, fuels are just the same. There's quite different spreadsheets. An airplane or a kettle. It could really work from mad. That's right. Yeah, it wouldn't stop being an airplane in the earth since if it was made of different stuff. That's very good. I think there's actually room for a lot of arguments about certainly the last three lines there, each of them. I think there's a first pass case you can make and what I'm trying to make, but then you go back and look at it in detail. For just the kind of reason you're giving. The reason I said something living is that if it's an artifact, I think that the way we use kettle or airplane is it something we made to meet our purposes? You see what I mean? Whether it's a kettle or a car or an airplane, isn't a matter of can you actually boil water in it? I mean, for the kettle, yeah. Because you might not be able to boil water in it, but that's just because it's not a very good kettle. But if you see what I mean, right? But there's something about the idea that well the reason it was made in the first place was so you could boil water in it. That has to be true for it to be a kettle. Something like that. But if these things are plants, then the reason they were made in the first place was not so you could boil water in them or if they're alive, then they have their own purposes. So it's not just that it's made of different stuff, it is a different function. You see what I mean? Their thing is that we're using as kettles, but they're not really kettles. We are the plants that are burning. Let's suppose they're alive, right? But we don't realize they're alive. They work in a very slow time scale and very quietly. So they talk to each other into the other artifacts into an earth, and humans never realize any of this. But they have their own lives and their own designs. They're not actually made in factories, though everybody supposes that they are. That's right, they call them kettles. They do use them to boil water. They haven't realized that that's not their function. Maybe this isn't going to work. Let me think about this. No, they'd say when the truth came out, when someone exposed the scandal of the so-called kettle factories, they'd say, my God, we all this time we thought kettles were artifacts made by us. But it turns out that kettles are alive, right? That could happen. That could happen here. That's right. When you made that discovery, there were still kettles, that's right. So if that's what happens in Twin Earth, they make this shocking discovery. We are going to say, well, hopefully they got in Twin Earth, this isn't a kettle, you must understand. They call it kettles. They call them kettles. Well, they're not really kettles. They're not kettles like our kettles. You certainly want to make a distinction between our kettles and what they call kettles. Yeah. Okay, this is fine. This is really meant to be a kind of exercise. Very good. Well, couldn't... Yeah, yeah, yeah. Yeah. Well, couldn't the basic physics of Earth and Twin Earth be different? So when you've got a rigid triangle or structure on Earth, yeah, triangles are a very stable physical structure. Yeah, you use them in bridges and all that. Right? Because you can't move a triangle as easy as you can in a square or something. So suppose that on Twin Earth, the basic, I mean, you're right when you say physics applies everywhere, but really there are local force fields and I don't really have the technical vocabulary to explain it properly. You're in a sector of the universe and the basic forces governing everything that goes on are really quite different. So the basic physical upshot is quite different. Yeah. Okay, well, yeah. I'm not saying this really works. I want to make a first-past question, right, and say there really is an issue here and it's not obvious. How much depth you can get out of any of these questions is not clear to me. You want to... Okay, so you're happy. You're equally unhappy, yes, yes. Yes, right. Maths are the same. Right, very good. There are real issues here. On the one hand, I don't want to spend too long on it, but on the other hand, I don't want to just brush it aside because these are real questions. With geometry, though, there's a distinction between pure and applied geometry. So pure geometry, presumably is going to be just the same in every possible world. Applied geometry, that's what I meant about how the triangle is rigid. Applied geometry seems more like an empirical thing about what happens to be the case in the actual world. Yeah, so that'll be the first-past answer. The next passes can't really make sense of alternative applied geometries, which is... Yeah, it's a good question. Yeah, okay. Yes? When you're moving from one... You may look like a spot case or a Madagascar case, a reference shift case. Straight off, it's not. You can turn it into a reference shift case by supposing someone who travels backwards and forwards between earth and twin earth. So it can become a reference shift case. So what you'd be saying is if the kettles on twin earth are quite different to the kettles here, then as you move backwards and forwards, slowly the dominant source of your information relating to kettles will shift on earth that was the artifact and twin earth that was the living creature. Yeah. So that dominant source will shift, so you could turn it into a reference shift in case. Is that what you mean? That's right. That's right. It is a different route. That's right. Does that shift the meaning? Is that a way of thinking how the meaning is different? Yes, well, yeah. You've got the picture. What's inside the head is just the same. What's outside the head is changing. And as that changes, your reference changes. Yeah. And what that shows is a meaning can't be identified entirely with what's inside the head. Yeah. Right. Yeah. You might say, well, John and John were not necessarily true to John. That's not an unreasonable way to put it. I mean, Fraga said in a perfect language, which sign would be associated with just one sense? Yeah. And that's a way of expressing it. I'm going to count words, so if there's a different meaning associated with them, that's a different word. Yeah. And you might try and make that explicit by saying, by adding a subscript or saying, well, in this sense or something, that's perfectly fine. But the only thing there is that it's a very rich notion of same word you're using. As you say, it's not just the sound or the shape. You're appealing to facts to do with the meaning of the reference to explain what you mean by same word. That's right. You're basically accepting his point by saying, in that situation, I'm going to call these different words. Well, yeah. Oh, do you mean the causal history of the word is different? Uh-huh. Okay, that's an interesting idea. Yeah, you could say the word water has a long and rich history in the English language. And over there, it will have a long and rich history in twin English. Yeah. So they are different words. Okay, that's fair enough. You could count words that way, and that's different to counting them in terms of their meanings. That's counting them in terms of things like their own causal origins as words, you know, looking back into etymological history. That's fair enough. But in that sense, difference of word is no barrier to the two words having the same meaning. You could have different words in Earth and in Twin Earth, but they could mean exactly the same. That's right. That's right. But it's not the mere difference of word that implies that. I'm going to give an example in a moment. Okay, so I say you can have twin Earth cases whenever there's lookalikes. Right? If you know something that looks just like a kettle or an airplane, but isn't really a kettle or an airplane, then you can have a twin Earth case where the lookalikes have, what's the word I want, triumphed around the majority. Yeah? You see what I mean? On Earth, you've got the regular thing and you've got a few lookalikes, and twin Earth is mostly what we call lookalikes. Yeah, so you can always set up a twin Earth case when there's lookalikes. So I think the clear stop point here will be words for psychological sensations, terms like headache. And you've got a headache in Earth and you've got a headache in twin Earth. Well, if they feel just the same, if the lookalikes for headaches in that twin Earth, then those really are headaches. I mean, there's no more to a headache than the way it feels. So if it feels just the same way, then it is a headache. It's really a headache. So I think the thing about ringers just comes, so far as I can see anyway, the thing about ringers comes to a definite stop a yen, a pang, or a throb of bliss. If these feel just the same in Earth, those in twin Earth, then they are just the same. Right, absolutely, yeah. Yeah. Our old friend, Plerotonin, absolutely is, right? Yeah, I agree that could happen. But remember, the word here is not a word for the physical basis of the thing. We're talking about the sensation itself, not its physical basis. So it's true that the word for that, if you're referring to the physical basis, that could vary between Earth and twin Earth. But what you're doing when you talk about the feeling is you're talking, you're trying to peel off the sensation produced by that underlying basis. And that's the thing that you can't make sense of it varying. I mean... Exactly, it's the same feeling, yeah. So I mean, when we're actually talking about words that stand for stuff that's inside the head, then varying the context isn't going to matter. That's the idea. So just to round out, in that situation, pain and Earth and pain and twin Earth would be different words, or headache and Earth and headache and twin Earth would be different words because their historical roots are different, but they would still be standing for exactly the same thing. Are we talking about the same inner sensation? Yeah, yeah. That's right, that's exactly right. Yeah, right. All right, that's the way of picking up that thing about serotonin and platotin. Right. And we could use headache like that, but what I say is we don't, and here's my claim, that, yeah, I mean, suppose you go to the dentist and the dentist says, I know this, getting this root canal work ordinarily produces a great deal of pain, but actually we've got a way of doing it so it doesn't feel pain, yeah. And then he does this thing and you experience the agonies of the damned and you say, I don't know what you're talking about, and he says, no, no, look, medical science has shown, we have you in the scanner the whole time. What's underlying this is not C-fiber firing. It feels like pain, but it's actually just a look-alike. It's not C-fiber firing. You see what I mean? Well, that's what I mean. I think it is the exact opposite, because in this case, we're only talking about how it seems, not the thing out there. Yes. You could say something watery or something like that, the watery stuff, meaning the stuff that gives me that kind of first quenching sensation. Is that what you mean? That's right. The only thing here is you need the distinction between the words that, as you were saying, are pointing to the essence, pointing to the molecular structure, or whatever it is. And the words that aren't doing that, the words that are just talking about your own in their life. And I agree with a number of the questions that there's a gray area where these cases really are more difficult, but they're not like the sensations. I guess that's the only thing I want to say. It's not quite as clear for them as for the sensations that you can't have ringers and leukolikes and twin earth cases. Yes. That's right. It is a special thing about psychological sensations. Well, in the sense in which you're using word, there are different words for X, Y, Z and H2O. That's fine. My point is only that sameness of word in itself is, sorry, difference of word in itself is consistent with sameness of meaning. And if that wasn't true, then translation from one language to another would be completely impossible. I mean, words in French have a different history towards in English. Yeah, they're different words. But the whole idea in translation is you try and match them up with words so you get the same meanings. I don't see that as easy, but the idea is that in principle it's possible. Yeah. I mean, it wouldn't be of just a mistake if you said to someone, you know, a UN translator or someone, but you realize the whole mistake you're making is that these are different words. That can't be a barrier to finding sameness of meaning. Yeah. That's right. Okay. The question is what determines the meaning of the word? Is it a settimological history? And the thing is that's completely parallel in the two situations. Is it what's inside the head? Not that either. So I mean, I think exact similarity of word, even if we don't have the very same word in your sense, is enough for him to make his point. I mean, it's a very fine distinction you're drawing. Okay. Come back to this. Okay. So I'm saying since there's no problem with your sensations, you can't have twin-earth cases for sensations. That's where the twin-earth thing stops. Is that all right? You don't have any causal or contextual determinants of meaning for sensation. Names for sensations. Yeah. Because they just are about what's inside your head. So if you else go to one of those for two swapping places, they're just going to have that. That is what it is to have the same sensations. But it's possible that it's only sensations preferring exempt from the possibility of twin-earth cases. I mean, we've already discussed a little bit. I hope I've managed to convey my sense that in these other cases it's difficult to be sure which way it goes. And that's all I really want to say at the moment. Okay. But maybe for all other terms that are causal or contextual determinants and then we can get on to the program of explaining all meaning in terms of what's inside the head plus those causal or contextual determinants leaving problem of sensation as a special case. But at this point the refutation of skepticism is very straightforward. Okay. Ready? Okay. Who laughed? I promise you it's very straightforward. Look, consider classical skepticism. When you're asked, might it not all be a dream? Might you not be a brain and a vat? When you think about the... I mean, my impression is a lot of you guys have encountered Descartes in some way or another. But you know the idea. It might all be a dream. An evil neuroscientist might be tampering with my brain. What you're asking in all these skeptical cases is are the causes of my experiences what I take them to be? Right? What the skeptic does is they say look, there are lots of ways that your experiences could be being caused that aren't by tables and other people and the lights and the blackboard and so on. You could be having just the experiences you're having right now but that could be all just productions of a so-priced brain. An evil demon. Madness. An evil scientist with electrodes plugged into your brain. Or maybe all there is in the whole universe is a large vat with lots of brains bobbing about in it and some vat tending machinery to keep the brains properly irrigated. Right? So when you think about it... You're looking quite pinned. So when you think about it these are all causal hypotheses. These are all ways of saying my inner life doesn't have a kind of causal context that I think it does. It's not other people on tables and chairs and so on. It's all this different stuff. So skepticism is saying maybe the causes of our thoughts are quite different to what we take them to be. And in that case most of our thoughts would be false. That's the whole thing of a skeptical hypothesis. That's what goes on in the meditations. Descartes gives you all these alternative causes and then says well how do you know it's not that one? But the whole assumption there is you can hold steady the contents of your thoughts while varying what their causes are. Right? So you know what thoughts you're having. The thoughts you're having are one thing. What's making you have those thoughts? It's quite another. So I take it the most making me have thoughts about people on tables and chairs and so on right now is a whole bunch of people on tables and chairs. And the skeptic says well as it were hold those thoughts. You could hold those thoughts fixed but something else might be causing you to have all those thoughts. That tending machinery for example might be what's causing you to have those thoughts rather than the tables and chairs and so on. So through these skeptical hypothesis you're supposed to keep steady the element inside the head but the trouble is that the whole point about these twin earth cases is that what we already agreed is that what this stuff inside the head is about, what you're representing depends on causal or contextual factors. So if you vary the causes of someone's thoughts you vary what they're representing. So if you varied what's causing someone to have their thoughts you will change what thoughts they're having and actually when you think about it the subject's going to come out as holding true beliefs. If you just vary the causes. The whole point so far has been that if your cause is to your surroundings they are generating the standards of rightness and wrongness. Starting with Kripke that's been the whole thrust is those causal connections to what's around you that set the standards of rightness and wrongness. So you can't just as a skeptic say vary the causal connections to your surroundings but keep steady the standards of rightness and wrongness. So here's Putnam when a brain in a vat an image of a tree the brain in a vat is not thinking about real trees How could it be thinking about real trees? It couldn't be thinking about real trees any more than it could be thinking about you or me. It never encountered a real tree. It never saw a real tree in it's life. It was born in a vat. There are no trees in the vat So it couldn't be thinking about a real tree It never met you or me it couldn't be thinking about you or me It might have images. There might be structures in its brain. There are just like the structures in your or my brain when we are thinking about trees. But whatever is going on, it can't be thinking about a tree because it doesn't have that causal connection to trees. It can't be thinking about Goudal. It never was causally connected. Never met Goudal, never met anyone who met Goudal, never met anyone who was in any way causally connected to Goudal. Yeah, it just lived its whole life in the vat. So what is it representing? Well when it uses the word tree, that will be in response to some activity in the vat-tending machinery and it's not causally disconnected to its environment. That's the whole thing about the skeptical hypothesis, right? That you explain how there could be some alternative causes for your thoughts and the current ones. So the vat-tending, there's going to be some pattern of activity in the vat-tending machinery that makes it produce the word tree. Just as for you or me, the regular cause of producing the word tree is, well, the presence of a tree. I mean, assuming that you have this kind of rudimentary conversation before you go around the compass saying tree. But something like that. So when the brain in the vat says low a tree, then just as you or I would characteristically be responding to a tree, the brain in the vat is responding to some kind of pattern of activity in the vat-tending machinery. And that's what it's talking about. Yeah, right. That's possible. I mean, that might happen to us that we could find that there isn't any one thing out there that we're talking about when we say trees. It's just a wild bunch of different stuff. But how should I say, we do operate in some assumption of regularity in our environment. Yeah, it operates in that kind of assumption too. Let's suppose for the moment that that kind of assumption is met. Yeah, in that case, it's talking about the presence of those electrical impulses in the brain. How should I put it? I do want to come back to this kind of point. I think this is important. But it's also important to remember that the objection to the skeptical hypothesis was never, but suppose the vat is unsystematic. You see what I mean? And how it produces these things. Yeah. If that really turns out to matter, we're a long way down the path. Yeah, so let's get to why it matters. So suppose then, in that case, if we've got the characteristic signature of electrical impulses and the vat that are causing the brain to produce the sign tree, then what is its production of the sign tree stand for? What's it talking about when it says tree? Class, is the brain then talking about trees? No, it is not talking about trees. It never saw a tree. Is it talking about the presence of that electronic signature in the vat tending machinery? Yes, that's what it's causally responsive to. That's what fixes the reference of its term. That's the whole point. It's a causal connection that fixes the reference of the term. Is there such a thing? So when it says low a tree, it's referring to the presence of that electronic pattern. Is that electronic pattern happening? Yes. Is the brain therefore right when it says low a tree? Yes. Wow. Okay. So on causal theories of reference, the brain is right, not wrong, when it thinks there is a tree in front of me. Yeah. And that's general. Yeah, in order for our science to have meaning, there must be that world out there. Okay. He's not saying we need to over test that we are not friends of the trees, especially if we were friends of the vat tending, because we wouldn't be friends of the trees. I know what you mean, but it's really very hard to get this across competently, because what you're agreeing with, I think, and what he's saying is that when you use the sentence, I'm a brain and a vat, you're saying something false. Because brain, remember, if you were in this scenario, yeah, in which that is your sentence, you utter, and you're coming out, it's coming out true, then there's also going to be your use of the word brain. Yeah. What will your use of the word brain refer to? Will your use of the word brain refer to brains? No. You never encounter a brain in your life. Your use of the word brain will refer to particular patterns of activity in the vat tending machinery. Are you identical to that pattern of activity in the vat tending machinery? No. So when you say, I'm a brain and a vat, that comes out false. Yeah. Yeah. The brain will use those very words too and say something true using them. Okay. We're going to go on with this for the next two sessions. I really just want to make one last point because we're on the hour. Okay. Remember, in the case of earth and twin earth, we said, okay, this is what's going on in your inner life on earth. This is what's going on in your inner life on twin earth. Yeah. But we interpret them differently because of the context. Yes. So what you're saying on earth comes out true and what you're saying on earth, twin earth comes out true and it works just the same. Yeah. I mean, it's true in both cases, even though the meaning is different. Yes. So that's all right. That's reasonably unproblematic. Yeah. Well, all you're doing now is substituting the vat for twin earth. Yeah. The vat is just another twin earth. What's going on inside your mind is just the same. What's going on in the context is different. So we just reinterpret the meanings of the signs so that everything you're saying comes out true. So you bought it for twin earth. You should be buying it for the vat too. So we have answered the skeptic. And on that bombshell, we will talk about this in another couple more sessions.