#152 Why AI Will Never Be Conscious

And Elsef, welcome back to the show. Thanks, Alex. What is the difference between intelligence and consciousness? both resist the kind of precise consensus definitions. But I think intuitively they are fundamentally different kinds of things. If we think about intelligence, it's about doing something. Could be about solving a complex problem or or solving any kind of problem. But in general it's about the capability to to do things functionally, behaviorally. Consciousness is primarily about

feeling and being rather than doing. It's it's in the words of Thomas Nagel more than fifty years ago now. He said, Yeah, it's this nineteen s uh seventy six, I think. Uh that for a conscious organism or a conscious anything, there is something it feels like to be that organism. And he doesn't mean feeling that it has to be necessarily emotional or anything like that.

simply the idea that there's some sort of interiority, there's some kind of experiencing going on. It feels like something to be me, to be you, but probably not to be a chair. And I think this this distinction between feeling and and and doing is is intuitively right. It doesn't mean they're unrelated. I think they may ver they're certainly related in things that exist, in in living creatures, for instance. but they may not have to go together in general.

Mm-hmm. You just wrote an essay, a prize winning essay, congratulations by the way. The mythology of conscious AI. And the reason I opened with that question is because you felt it important to tease apart those two concepts and that's got a lot to do with the fact that in our search to understand consciousness, to figure out what's going on and why there is anything it's like to be anything. We look to what we know, which is that I know I'm conscious, you know you're conscious.

And we know that there's intelligence to some degree in both of our brains, I like to think. And so we kinda make this assumption that maybe they always come together in that kind of way. You start talking about this to try and pull those concepts apart a bit, right? It's one aspect of of the of the discussion. So I think the overall framing for this is to try to uh try to reason through

what has become quite a confusing topic, which is whether artificial intelligence could be conscious. It seems to be intelligent at least in some ways. But there are various views and and a lot of kind of I think somewhat unexamined views about whether AI can be not only smart but also also conscious. And one part of the the discussion is to examine our own psychological biases. Why might we even think that an AI system could feel as well as do intelligent looking things?

And part of that is indeed to recognize that just because things go together in us, like intelligence and consciousness, doesn't mean they have to go together in general. Um across all living creatures I think there is this this strong relationship. So it's certainly the case that for certain kinds of conscious experience, you need to have certain kinds of cognitive capability. So for instance

if you're gonna have the experience of regret, then you need to have the cognitive competence to envisage alternative courses of action and their possible outcomes. If you

don't have like the functional capability to do that, then you can only really experience something like disappointment or or maybe even sadness. So the relationship goes goes that way. Uh but It's not clear that Um in virtue of being cognitive in that way or intelligent in some way, that you have to do that in a way that that is accompanied by consciousness. Mm. So you said this has become quite a confusing topic. It's a bit of a sort of

Buzzy issue. I almost I'm almost sort of hesitant to talk about it. In fact, when when I've done episodes about consciousness, I've kind of avoided the topic of AI consciousness because it's like asking whether we live in a simulation or something. It's like it's people are talking about it and it's there's there's kind of nothing super interesting to say about it. People kind of go, Oh, like, you know, maybe, who knows, we wouldn't be able to tell.

But you've written a really interesting essay, not just sort of going like, Well, look, you know, how are we gonna be able to tell if it's conscious, but specifically talking about the nature of consciousness and its relation to living organisms and

I think that weirdly, you kind of want to start by by pulling apart the two concepts. You wanna say, let's not assume that all consciousness and all intelligence works the same. But the place you end up is kind of where our intuition start with, which is that, yeah, like to get this consciousness You need to be essentially a a biological organism. And I wanna maybe just talk through how we sort of track that trajectory. So Where to start? I mean

The idea of AI consciousness is the idea of mechanistic consciousness, that whatever it is our brains are doing to produce consciousness can be replicated with a machine. And There are thought experiments to this degree of like um taking every single neurone in your brain and just like replacing it with like an electrode or a transistor or whatever the relevant analogous part would be.

and that if I did that for one of your neurons, just swap them over, probably everything would function, you wouldn't really notice any difference. And slowly over time it feels like we should be able to, in principle, swap the the biological electro signals in your brain with mechanical electro signals. But presumably at some point you think

this would sort of break down, or it wouldn't work in the first place, or there's some kind of barrier between those two ways of trying to produce experience. And I just wanna know why you think that's the case. I think that's a good place to start. Um but let me just make one sort of nuance to how you how you set this up and and this is that the idea of of AI being conscious is not

just that it the idea that it's the result of the operation of some mechanism. It's usually the more specific claim that the kind of mechanism in question um is implementing computations and it's in virtue of those computations that consciousness happens. This is in the philosophical assumption of computational functionalism rather than functionalism in general. Functionalism in general

is the idea it's quite a liberal idea really that consciousness is a property of the functional organization of a system, um, like a brain, an embodied, embedded brain. But that can encompass things like its internal structure, its causal architecture, can be pretty specific. Computational functionalism is a subset of that, and it says that It's the computations that matter.

And typically when people think about computations, they think about computation in a sense inspired by Alan Turing, um, which is that computations in the Turing sense are independent of the material, independent of the substrate. there's a sort of sharp division, if you like, between the software and and the hardware. The algorithm is what matters and the algorithm is a mapping from one sequence of symbols to another sequence of symbols. And it's that mapping that that matters. Mm-hmm.

So it's it's quite a strong claim, really. Um and that's the claim that I think is is really it starts to you know it looks like it's quite on shaky ground the more you examine it. And one way to examine it is indeed this kind of neural replacement scenario that you mentioned. So this is often It's often sort of put on the table when people want to justify the idea that consciousness could be implemented in silicon just as readily as it can be implemented in in carbon. Right.

And as you put it, the the thought experiment it goes back to I think David Chalm has popularized it, but it's got ancestry before that. Is indeed I'd say one neuron. I replace it with a perfectly functionally equivalent silicon alternative. And it has to be kind of perfect for the thought experiment to carry through, because if it isn't, then you can immediately say, Oh well, those differences they may matter.

And I can do this for one neuron. Um, you know, neurons fire spikes, why not? Uh and almost certainly nothing will happen to your consciousness if I do it for ten, is anything gonna happen? Probably not. Then I can do it for a million, eighty-six billion. And So this is pushing the intuition that if n if it doesn't matter for ten, why should it matter for any number? Therefore, substrate independence, what matters is the the sort of functional organization.

Firstly, I think it just begs the question. Ned Bloch pointed this out, another philosopher. He said, well, you know, maybe in fact it would be the case that if consciousness depended in some way on the actual stuff, then as you replaced more and more neurons,

um you would uh experience consciousness fading or consciousness may fade, you may not even notice as the subject of that. So it does kind of beg the question. But I think there's a more fundamental problem, which is that like many thought experiments of this kind, the more you look at it, the less conceivable it is. Uh-huh. Uh it's really, really

unlikely that you can perfectly replace a biological neuron with a silicon alternative. In fact, you can probably only replace it with another neuron and probably the same one. So there's one g one example which I really like is that Um there are many u examples you can you can choose, but one example is that some neurons fire spikes to clear the waste products of metabolism. Mm-hmm. So how do you replicate that in silicon? You've got to give the silicon a kind of metabolism.

two and that's not the kind of thing that silicon can have. So that thought experiment to me it underpins a fundamental difference I think between brains and Turing based digital computers, which is that in brains you just can't separate what they are from what they do in a way that's sort of enshrined into how we think about the kind of computers that we're familiar with and the kind that are running all the server farms that underpin all the language models we talk to.

Yeah, that's so interesting'cause like when you you gotta think about how far you wanna push this because somebody will say, No, no, no, but you don't understand, like, we're gonna just perfectly replicate the neuron and then yeah, we'll we'll perfectly replicate the

The the body as well, if we need to come up with metabolism, sure. And it's like, okay, but to to what degree? So like on a macro level, you look at a neurone and it's got inputs and outputs. So you replicate that with silicon, but it's not quite complex enough. It doesn't have all of the inner workings. So you go down onto a

onto the level of the parts of a neuron and you replicate each one and you stick them together. But it's still not quite there. Well well let's just keep going deeper until until what, you get to like the molecular level and it's like, oh I'm just gonna create a perfect replica of a neuron at a certain level of resolution, in order to do that, you would just be creating a neuron. Exactly. and be you'd be below the level of recognizable like silicon. It would just be

electrons and protons that you're sort of ordering in some in some way. And so it's like Yeah, maybe you could create a a silicon creature, but uh you kinda have to be a bit more specific and and be a bit more detailed. And what you're actually doing is not building a computer and calling it conscious, but just building this Frankensteinian biological being and calling it artificial just because you've created it with your with your bare hand.

Which I think is is is pretty reasonable. I mean there's a whole other branch of of sort of artificial uh things and which is synthetic biology and we have people creating brain organoids. in synthetic biology labs, which are clusters of of cells which are brain they're neurons and they're usually derived from human stem cells. So they're in they're in fact human neurons. And they wire up together and they start to show activity.

um, they don't really do anything very interesting, at least not yet. But indeed they're made out of the same stuff. Now it's it's hard to say whether we n we can't say for sure that that is a is a necessary condition. But if you're creating something that is literally made out of the same stuff, then that whole uncertainty goes away. Mm-hmm. Y you no longer face the question of whether you could do it in silicon'cause you're not doing it in silicon anymore.

So the position that you land on and mythology is a is a is a weak term and a strong term. Because it's not saying, you know, this is complete nonsense, but it's definitely saying that there's a bit of weird stuff going on that we need to iron out. Do you land on the position of like, based on my understanding of consciousness and the way that brains work, AI just cannot be conscious? Or is it a more reserved, like

Let's slow down a bit here. Like, maybe it's possible, but the general conversation around it is a bit confused. Like, how strong is the condemnation of this this view? Very sceptical, but I think in discussions about what kinds of things are or could be conscious, we need a certain residual humidity. Sure. I think

Simply because we just we don't know. We know so I'm a phenomenal realist as well. I think conscious experiences exist. So there is something about so from that starting point, I think there's something about the embodied, embedded

biological brain, um, that is sufficient for consciousness. The game is to figure out what that is. Now computational functionalism of the sort that would license claims that language models or other kinds of digital silicon AI could be conscious, is making one specific bet that below the level of the algorithmic description things don't matter.

But there are many other things that might matter that are much more tied to a biological substrate than an algorithm which by definition is is divorceable from it. So I I think that Anyone who says that AI could is conscious or impossible for it to be conscious is overstating what can be reasonably said. But having said that, I think digital silicon AI is is so unlikely. And I think the reason I think it's so unlikely is partly because there are many reasons

why we are likely to overattribute consciousness to these things that say more about our own cognitive biases, these conflations of intelligence and consciousness and the specific seductions of language as as something that draws us in. Yeah. And so I think that says more about ours and about the system, but more fundamentally, because of this. deep way in which you can't disentangle what brains are from what they do, what it's a a property some people call generative entrenchment.

This makes it very unlikely that the computational level, indeed if there- even if there is one in the brain, that makes it very unlikely that that what matters, that that can carry the load of everything that that brains do. Yeah. And if you put those together, then I think There's good reason to be very, very sceptical that AI as we know it now is capable of consciousness.

Yeah. We'll get back to the show in just a moment, but first, on days like today when I'm working and recording multiple episodes, I sometimes just like forget to eat. which would be bad enough if I wasn't already really bad at keeping on top of my nutrition. But also I kind of don't want to spend any time trying to make some food. And luckily in situations like this,

Huel, today's sponsor, come to the rescue. That's H U E L. This is the Black Edition, and this bottle contains a complete meal 400 calories. thirty five grams of vegan protein, twenty seven vitamins and minerals, and coming in at under five dollars. This is also the chocolate flavour, but Huel comes in all kinds of flavours, and different types as well. There's the classic edition, this black edition,

There's a light addition, and of course the powdered form too, whatever you prefer. I drink Huel almost every day. It's extremely convenient, it's gluten-free, there are no artificial flavourings or colourings or sweeteners, it's high protein, low sugar, low cost. And if you go to Hewell.com forward slash AlexO'Connor and use the code AlexOConnor at checkout, then as a new customer, you'll also get fifteen percent off. Complete nutrition while saving your time and your money. And with that said

Back to the show. I I

I wanna talk about those biases that you talk about in the piece, the three sort of facts about human psychology that make us sort of want to think of AI as conscious. But I'm also really interested in in what you said and what you wrote about what something does versus what it is. I get a lot of stick for wanting to know what things actually are more than just what they actually do. And it it causes a bit of a fuss sometimes when I really become a stickler on the point. But when you say

That in a brain you can't separate what it is from what it does. What what precisely do you mean by that? I don't think I I mean it in this metaphysically loaded sense in what you mean. What is the essence of of of the universe of of reality. But but I don't think I'm making any kind of claim that's that that strong or that controversial. Um I'm completely happy in this conversation to think of

what something does as related to what it is and if you and if you look ask what it is, you can pull it apart a bit more from a at least a methodological reductionism and it you can explain what it is in terms of what it does at at lower levels. Yeah. It's just that the more you do that, the less flexible you become with respect to realizing those same kinds of functions in different kinds of materials. Hm. So

in you know, it just takes something very very uncon uncontroversial like I don't know, building a building a bridge across a river. Um Only certain kinds of materials are up to the job. Yeah. Yeah. You you just can't build a bridge out of string. You know, it's not going to maybe you can actually if you wired anyway. It's not the it's not the ideal substrate. You can't build it out of out of cream cheese or water. Yeah. So

There are some things whose properties depend on on the material um that they're made of. And It may well be that biological systems. uh are subject to many of these kinds of constraints. Yeah. Yeah. So that's a it's not a it's not a radically controversial claim at all. It's not saying there's something magical about about the substrate, magical about about carbon. Mm-hmm. I think there's kind of weak and strong versions of saying the stuff matters. One is saying that

What what matters is what it does, but what it does is only realizable in certain kinds of material. Yeah. The computational view tends to push back against that by saying, Well, look, the whole point about computation is that um you can you don't worry about what it is, you know, any many things can can do it. Mm-hmm.

But that has to be justified. I d I think the problem is you can't take the computational view as a starting point, as an assumption, for granted. You've got to give good reasons for why. computations should be sufficient. So that's there's a that's the relatively uncontroversial view, just saying that, okay, consciousness may still depend on the functional organization of a system. But that that functional organization cannot be realized, implemented, instantiated

in non biological systems, or at least certainly not in in arbitrary materials like silicon. Maybe other things can do it, but maybe many other things can't. There's a stronger version which which which I am kind of attracted to, but I I'm not at all sure is right, which is the stuff matters in a more fundamental way, in a in a similar way to, let's say, how um the molecular structure of H two O matters for for properties of water. And here, you know, I I think that it's not

It's not an unreasonable position. Um there is something that that sort of explains why there's phenomenality at all to you know our brain, our embedded, embodied brains. And that factor may be something like the energetics of metabolism, the auto the self-producing autopoietic characteristic of living systems. And I don't know if that's true, but I think it's uh it's really worth considering. It's at least as plausible in my mind as the idea that it's a matter of of computation.

Yeah, because... a a bridge can only be made out of certain materials, but it still does rely on a particular functional complexity and a particular organization of that material. But to say that the the way in which this material is organized gives rise to something like a bridge is not to say that that's the only thing you need. You also need the material that

allows those properties to actualize a bridge, right? So you can't make it out of cream cheese. And in a similar way, like You know, the the functionalist or someone who thinks that a computer can create consciousness is a bit like someone who says, Well, let's just take, you know, every like bit of wood or concrete and replace it with a bit of cream cheese.

And instantly it's just d that's just not gonna work unless you really go down to the level of like, well, let's replace every atom in the cream cheese with every atom in the But then you've not got cream cheese anymore, right? Then you're talking about something different. So I think d y you're probably gonna then need to have some understanding of

what it means for something to be biological, what it means for something to be like a a living system, and that's only gonna go down to a certain level of complexity, because once you go deeper you're just doing like atomic physics. But something about being alive is crucial to consciousness, but is that more because of like the materials that living things are made out of, like carbon, or is it more to do with the sort of functional reality of what living systems do? Or is it both together?

I think this is the really exciting open question. Yeah. So I think it and it's the third part of of the general case against uh conscious AI as we know it. You know, the first is the collection of biases that we have.

The second is the scepticism that computation or substrate independent computation is sufficient. But the third is is equally important and more challenging in in my mind, which is No, th the first idea is about bio this this view being biological naturalism, that that consciousness is a property of living existence.

I think some of the first expressions of this were a little bit um blunt, if you like. They it's just it's almost an identity. No positive reasons, just consciousness is a property of living systems. That's that. And I'm not satisfied with that kind of explanation. I think you've got to give some positive reasons for why. What is it about biological systems that that matters for phenomenality? And

Yeah, I I think there are no knockdown arguments for why this has to be the case. But one story Which I give the outlines in in this essay that we're talking about and s longer versions elsewhere, is A story that runs from thinking about the brain as a prediction machine in which the contents of conscious experiences can be understood as.

underpinned by brain-based predictions about the causes of sensory signals. I I usually have called this the concept of a controlled hallucination, something like that. Um And that can be thought of computationally because it's all about Bayesian inference, but it doesn't have to be implemented computationally in the brain. I don't think it is implemented computationally. I think it's done in in in different ways.

And the story tries to draw a line all the way through from this process, which tells us things about. why conscious experiences have the characters they do, have the phenomenal properties they do, all the way down to Processes like metabolism and autopoesis, where living systems by their very nature, have to maintain and repro and produce not only reproduce, but produce themselves, keep on regenerating their own material basis and maintaining themselves

out of equilibrium with their environment, out of thermodynamic equilibrium with their environment. I mean that is what it means to be or one part of what it means to be alive. If you're in thermodynamic equilibrium you're no longer alive. And that too can be understood as a kind of process. of minimizing um the surprise of sensory data through this All right. difficult to unpack but very interesting free energy principle. Okay. Um, from Carl Friston and so on. Yeah.

Now there's a lot a lot in there and a lot of steps, not all of which are very clear. In fact th I think the most the trickiest step is to go from the idea of free energy in the free energy principle, which is all about or at least primarily when applied to life, about thermodynamic free energy, um, of the sort that that metabolism is involved in. So real, you know. energy work being uh done to transform substrates into energy that can be used by the cell to reproduce its part.

connecting that to this kind of more information theoretic free energy that corresponds to prediction error when we think about the brain as a prediction machine. Now you can line these up, but but I still I'm I'm personally not satisfied yet with with how this works. Hmm... Okay, I see. Okay, so... I wanna talk for a moment about you you mentioned this briefly earlier and you wrote about this too, about the way in which specifically like L LMs have just

burst open the door to credulity about conscious AI. Because We've got artificial intelligence doing all kinds of different things. You know, there's i in a self-driving car, like chess computers, whatever. But very rarely are you playing against a a chess computer and think, gosh It's so good at at, you know, knowing how to checkmate me, it must be conscious. There's something about language models that make people go there's something funny going on. And you know, if if the brain is

making predictions, if the brain is sort of working like a prediction machine, people might say that's kind of how L L Ms work. They they don't actually speak exactly, they don't use language, they just predict.

you know, what you would like to see next, what word you would like to see next, and then they'd sort of successfully produce it. There's something a bit m like eerie, maybe, about the language thing. And you write about how It's a little bit suspicious that something that so obviously is just trying to mimic human behavior has made us go, oh, maybe it's conscious. Uh yeah, I think that's that's part of the mythology aspect. That that there's a there's a sense in which

some motivated reasoning is going on here. Like we we we're still very human exceptionalist in our in our outlook. Yeah. I think. And we can think of kind of the march of of of science and philosophy as as repeated attempts to challenge or at least nuance this human exceptionalism because there are things that are distinctive about human beings, but you know, we're not at the centre of the universe, we're not unrelated to all other animals.

And I think cognitively and in terms of consciousness we're part of nature as well. Um, language has been one of those things that we think sets us apart. Yes. Uh this is actually under pressure in many directions, right? It's under pressure from L L Ns'cause they ha I think it'd be It'd be unkind it'd be unfair to say they don't have some form of language. Unkind. Unkind, I don't mind being unkind to the AI, but but we shouldn't be for other reasons for our own our own psychological health.

No, I know what you mean. And other animals are all these interesting actually applications of AI now to decode non non human animal communication. So I think language is gonna be itself a a little bit on unstable ground as something that motivates our our human exceptionalism, which is part of this mythology of of AI. But let me come back to to the point. So you mentioned chess playing programs and people not projecting consciousness into a chess playing program.

That's probably true, although when uh Deep Mind had AlphaGoat, there was this famous move. Mm-hmm. I don't remember people thinking that AlphaGo was conscious when it played move thirty seven or whatever the number was. ご視聴ありがとうございました there might have been a temptation to project some kind of mind into there, just a very uncanny one. The example I think is is easier is uh Alpha Fold.

Which is another AI system developed by DeepMind which helps you predict the structure of proteins. Very, very useful. Mm-hmm. I've never heard anyone describe this or worry that it might be experiencing things when it when it's doing its protein folding algorithmic acrobatics. But under the hood, it's very, very similar to to L L Ms. You know, it's an it's a bunch of neural networks and transformers running on silicon hardware, tuned up in different ways, trained on different data.

But if somebody thinks that GPT is conscious but AlphaFold isn't, You know, I'd I'd be really interested in what what justifies that distinction. It's kind of hard to to justify. Yeah, and it seems to just be sort of that it passes the Turing test, right? That it like is indistinguishable for us from a conscious agent. But again, that's a very sort of it it looks this way, towards us, rather than towards the thing. And it's it's so easily easy to be to be fooled by these kinds of things.

That's right. That's why, you know, I think if we if we are too tempted by seeing things through the lens of what a conscious human being is like and bind consciousness language and intelligence too close together. This can lead to both false positives and false negatives. You know, we can see consciousness when it's not there in the statistical acrobatics of LLMs, and we might miss consciousness where it really is.

Yeah. As we've done in the whole history of human treatment of non human animals, and as we might now do in synthetic biology and organoids.

Yeah, and of course the the consciousness that's in the atoms that make up the universe that I I know you you You have a lot to say about um but I i we do I think we do sort of both rely on this intuition in different directions in that like, you know, where I wanna go off on my weird tangents about idealism and panpsychism and all that kind of stuff, I I often begin

by in intentionally just trying to isolate consciousness. Before we can study anything and look at its nature, you've got to isolate the thing that you're talking about and You know, consciousness is not the same thing as the content of conscious experience. It's like, you know, I'm seeing things right now, I'm seeing a chair.

But like the the the visual of the chair is not the same thing as consciousness. It's one of the things that's happening to my consciousness. I like to think of it as and so I I like to ask people, you know if I close your eyes, if I took away your eyesight, would you still be conscious? And the answer is yes. And you can take away hearing and they're still conscious. You can take away memory and they might still be conscious. And

Whatever you're left over with is the thing that consciousness is. Now for me that allows me to say, and that means consciousness is really simple and it could abound in the universe, but it also allows us to say, therefore be extremely careful

in saying that well, because this computer has memory, maybe it's got cameras and it can see things, maybe it's got a sense of humour. I think the test to run is Whatever quality you're looking at in an AI system to say it's conscious, if you took that quality away from a human and they would still be considered conscious, then it's not a good metric to use, you know?

a good argument, I like that. I think it's I think you're you're right that if you can do that, you certainly can't treat the presence of that

As a sufficient condition. Yes, quite. There might be interesting things about jointly sufficient conditions and so on, but but I think it's certainly a good question to ask oneself. Yeah. Um And I you know, this this thought experiment, mm-hmm, this is one I quite like actually, unlike neural replacement thought experiments, this idea of stripping things away because it does help us at least try to get out of our human centered perspectives a little bit.

And you know, there's an old I think it's a Greek version of this called Avicana's Man. Yeah, yeah, I know. man, yeah. So the floating man again you strip away I think it's more about self than consciousness, but Yeah, he's he's trying to to it's sort of a a a prefiguring of the of the Cartesian, you know, I think therefore I am type thing of like taking away all sense data essentially. And the reason he's

floating or flying is because he's not supposed to feel anything. There's no touch, there's no sight, there's no nothing. And yet you would still just have this thing called like awareness. And and yeah, it's it's trying to isolate and I think in a way Descartes was kind of trying to do the same thing, but a in a slightly less sophisticated or um helpful way for this particular application, which is like

What is the thing? Descartes, like, well maybe my sight is deceiving me, maybe this chair isn't really here, all of it but what's what's left over as like the nub of experience itself? And yeah, uh Avicenna does the does the same thing. And I think whatever we're left with, it's not gonna be like recognizably human. That's right.

Certainly not. And that that would be, I think, very strange. Yeah. That would be basically to sort of deny that that consciousness could be expressed outside the human case, which which I think would be a a very wrong claim. I was thinking of Avicenna's man Yesterday because I was in a flotation tank. Oh cool. Yeah.

And and um you know, this I do this now and again and sometimes it's relaxing, sometimes it doesn't go so well and yesterday for various reasons. I don't know why it didn't go so well. And of course Your eyes are closed. It's quiet in there. Nothing perfectly quiet, whatever, but it's pretty quiet. You're floating. So you do kind of lose the sense of your at least your body configuration. Kind of not so sure where my hands are. But

Other senses come to the fore and yesterday in this flotation tank, you know, just my the sound of my heart beating just became very, very dominant. So we have all these senses of the body. And I think this is relevant firstly'cause it's just it's hard to uh it puts pressure on the idea that we can just strip away these centers because other things will bubble up. Yeah. But what I don't what I think it points to, so where I land when I try to imagine what would be left.

Where I land is something like the feeling of being alive. Right, I c I see. What does that mean? It's a bit it's a bit unclear but it's Yeah. It's it's what I imagine might be there when you strip away indeed all extra receptive perception, all visual, auditory content, all cognitive content too. So not the Cartesian rational thinking that's left. That that your mind quietens. So this is some overlap with states of pure awareness in meditation and and some psychedelics.

So you strip that away, you strip away the experience of m emotion, of specific emotions, you strip away the experience of the body as an object in the world, you strip away the first person perspective. Memory is gone. Intention is gone. Can you strip away is there anything left and could you strip that away and still be conscious? My my intuition is a good way to think about that is this basic feeling of being a living organism without shape.

boundary specific content, yeah, but that it's kind of persisting in time. Yeah. In some way. I mean Descartes famously to establish his mind body dualism, keeping them separate, the the way he gets there is just by saying like, Well, I can conceive of myself existing without a body.

And I can certainly conceive of my body existing without my mind, just like a dead corpse. And although they might be tied up in various ways, the the fact that they are conceptually different means that they are different things. They might they might coincide, but they're they're literally conceptually, you know, separable. And that's that's basically his sort of principal grounds for saying that they are different types of things.

I want to ask you if you can imagine yourself without a body. And most people I think sort of go like, yeah, sure I can sort of imagine floating around in the void. But I mean given everything that you know about consciousness and your understanding of how it works. Can you actually make sense of some kind of conscious being that has no embodiment whatsoever? Or is that actually something that you now, given your views, sort of can't imagine?

Embodiment in the sense of having a physical substrate. Yeah. Or in having a body interacting with an environment. Just having a physical Okay, because the diff I'm I mean the uh yeah, I just mentioned that because one can think of, let's say, an organoid as it has a physical substrate. Mm-hmm. But it doesn't have a senses or or motor effectors or legs or any it doesn't have limbs. So it's kind of disembodied in the sense that we might use embodiment But it has no.

contact with the outside world or anything. But no, I'm I mean like not even not even having that. Okay. Can you imagine I mean even like conceptually, can you imagine just sort of existing in in the void with no physical I think conceptual conceptual imagination of this sort is too low a bar. I don't say much store break. Yes, you know, I mean they're concepts. I can I can create a concept in which there is a disembodied consciousness. Yeah. Can write stories about it.

Uh, but I think this is you can't really use that to carry much weight. Yeah, sure. Um it's a problem with these kinds of conceivability arguments in general I think. So it's it's it's a bit like can I imagine a Boeing seven four seven well they they're out of service now. Can I imagine a Boeing seven eight seven fly backwards? Through the air. Well, yes, of course I can imagine it, I can picture it.

But the more I know about aerodynamics and engineering, you know, nomologically, so given the laws of physics as they are, yeah, you can't have planes that fly backwards. That's where I land. Yes, conceptually I think it's possible to imagine these things. But if I want to understand how things are in the world a as it is, with the laws of nature as they are, then the more I know about the brain, the body,

how intimate these connections are and how explanatory they are as well. Then it becomes Yeah, it becomes less it doesn't really mean anything to say that I can conceive it. Yeah. And I think that also the reason I asked you that was because

There's a level at which you can conceive something and then upon learning new information you suddenly can't. Like a child can imagine a plane flying backwards because you just picture it in your head. But once you know how planes work, once you know how lift is generated.

It's like you actually kind of now can't imagine the plane flying backwards. I mean you can you can literally imagine a physical object moving across the sky, but you can't imagine it flying backwards because flight is a is a is a physical concept that is applicable to the laws of physics as as we know it, you know.

And once you understand on a deeper level, like it's just not even something you can properly conceive of, unless you're just sort of intentionally fooling yourself. And if you know or are convinced that consciousness is a product of living systems Then maybe sort of Descartes was just wrong. You shouldn't be able to conceive of such a thing, at least in the real world, you know.

I think that's yeah, the more you know about it, the less likely it becomes that that these things are separable. Um, this goes to the neural replacement thought experiment as well. If you don't know anything about neurons, it's very easy to imagine that you could replace one. with something made of silicon. Or if you if you've kind of reified the metaphor of the brain being a computer to think that it's really is a computer, then you might also think

that you can replace a neuron with a with a silicon thing because computationally you might be able to say they could be equivalent. But the more you know about how real neurons work, what they do How their collective behavior self organizes and assembles and changes over time. Then, just like a plane flying backwards, It becomes less and less conceivable for the world in which we live, for the kinds of things in the physical world which we have.

Yeah. We were just talking about Matthew Cobb before we started recording. I I just had him on my show and

He's got this book, The Idea of the Brain, which is a history of the way people have thought about the brain. And he sort of try he said to me that he wasn't really sure how to structure the book until he realised he could do it by what was the leading analogy? Like what what did how did people think about what the brain was? And Like it's astonishing that Basically, humans have always just picked the most complicated thing that exists.

and just been like, brains are like that. You know? F for some ancient writers a brain is like a is like a complex sort of musical instrument. Or some or for for some people, uh w when like mechanical um what's the word with you know pumping air through tubes and stuff, hydraulics, you know, became a thing. The brain began to be seen as this like hydraulic

system and air was being pumped through the veins and stuff. And then we discover electricity and we're like, oh the the brain is electrical and we invent computers and we're like, oh no no, it's not like air going through the veins. It's like it's it's kinda like zeros and ones and it's like bits and it's And we start confusing the map for the play. 'Cause we start forgetting that this is just an analogy to help us understand. And

we'll never know what the next big technology is going to be. But, you know, I like to reflect on whoever it was in like the eighteen hundreds or nineteen hundreds who said, Oh, there's nothing more to invent anymore. Like we're done. I can't possibly conceive anything. I think that whatever comes next, we're probably just gonna say, No, no, a brain is a bit like that, but it's I mean it's already happening a little bit, isn't it? I mean, e even though computers are still involved

We have AI, but we also have things like the internet, these very distributed sort of self organizing systems. So so the metaphor is beginning to to alter, even if it hasn't completely given way to a new technology altogether. But yeah, Matthew's book is great. I think it it really makes the point that we we always have to be careful not to confuse

The metaphor with the thing itself. This is like Whitehead's fallacy of misplaced concreteness as well. We we just we'll get ourselves into trouble. It doesn't mean that the metaphor is aren't valuable. And I think the the the metaphor of the brain as a computer is a particularly tricky one because it's not just that we're taking a complicated technological system and and trying to find the ways in which it might be analogous.

the idea of the brain as a computer also draws in all these theorems from computer science and physics. um about the generality of computation as well. And there's a an ongoing debate about what physical processes count as computation. Is everything computational? And we have like John Wheeler that everything is computation. It's fundamental. So it's a bit of a trickier one, but I think it's based on On two specific Two specific events.

that when put together give rise to to a strong temptation to think that computation is is all there is. And the first of these was from Turing, who basically came up with the idea of of a of an algorithm, of Turing according of of computation according to Turing, this idea of mapping

sequences of symbols to other sequences of symbols. And he showed this was very, very powerful with the idea of the universal Turing machine, you know, a machine, an abstract machine that could implement any algorithm. Mm. But what what does that mean? Like when when you say algorithm, what are you talking about? Exactly this an algorithm is something that maps one sequence of symbols through a series of steps to another sequence of symbols, like a mathematical rep recipe. That's an algorithm.

That's you know, people might use it loose more loosely, but that's technically, in my understanding, what it is. Mappings from symbols to other symbols. You can do a lot with that, but it's not clear that everything is a matter of mapping symbols to to other symbols. And indeed, Turing's classic paper on this, which is now like ninety years old. Wow.

was motivated by the the idea of the halting problem. The idea of showing that there was some even within computer science, there's some functions which could not be solved algorithmically. So there are limits even there, but then many things in the real world are not algorithmic, uh things that are continuous, things that are inherently random, being some examples So there's more to the universe than Turing computation. And then the second event was Walter Pitts and Warren McCullough.

right there at the beginning of AI and of cybernetics, who showed that simple neural networks, if you just had these you know these co computational abstractions, if you like, of artificial neurons that summed up their inputs and generated an output. those could implement logical operations and given other things like storage and whatever

they could be Turing complete. They could implement any algorithm. And you put these two th things together and they're both really important observations and you you you understand that If you strip away everything about the brain apart from, you know, idealize it in terms of this network of neurons that are connected, um, that just sum up their inputs and pass on outputs. You can get everything that Turing computation can give you. And that's very, very powerful. And I think that's why.

For decades now, people have sort of thought that we don't have to worry about anything else in the brain. We can throw it all away, because at that level of abstraction, we get everything that Turing computation can offer. That's useful to know, but Turing computation can't do everything and it's very unclear that you know it can realise

all the properties of the brain. And when you look at a brain you realize that in fact it's all it's you can't separate what it is from what it does. That really puts pressure on the idea that Turing computation is all that matters. Mm. We we talked about this earlier. I mean you you were sort of talking about separating what a thing is from what it does and we talked about bridges and stuff, but

You say in the piece that like with a computer, you can separate what it is from what it does, but with the brain you can't. And I'm I'm still a little bit unclear on like what the difference is and and and what you mean specifically. Like maybe you can explain why you can with a brain and can't or can with a computer and can't with the brain. It's partly a kind of theoretical thing and it's partly a practical engineering thing. So

the practical engineering thing is computers are useful because because they're built this way. You know, we can run the same program on different computers, they they do the same thing. We can run different programs on the same computer and and they'll do

different things. They have this kind of perfect interoperability which makes them useful. And that emerges from the fundamental principle of Turing computation, which is You know, people argue about it, but there's a general consensus that computation in this sense is

supposed to be at any rate substrate independent. Yeah. That once you've defined the algorithm. Yeah, that's all you need to know what the system is is going to do. Yeah. So long as the stuff that's implementing it is capable of of implementing it. That's that's enough. And brains firstly

Evolution didn't design brains for that kind of interoperability. You know, how if I took the functional dynamics of my brain and it they don't have to work in in your brain, they won't work in your brain. But there was never any evolutionary pressure for that. in the first place. In fact there's evolutionary pressure the opposite direction, because maintaining this sharp separation of scales, you know, insulating one level of dynamics from from another.

is energetically very expensive. Mm. You know, if you just think about a digital computer, it takes energy to make sure that ones remain ones and zeros remain zeros. That's one reason that AI systems are so much more energy inefficient than than real brains. Mm. If you want energy efficiency, which evolution cares about

And you don't need this sharp separation of scales, you're not gonna get it. You know, you're gonna get systems where what it does is much more entangled with what it is, because evolution doesn't require there to be a separation. Even I think even more interestingly, and this is something which I think is a very exciting line of work uh that's opening up at the moment, there may be functional benefits for systems. that are entangled in this way, that are scale integrated in this way.

Um they may be able to do things that are much harder to do in systems where you try and enforce a sharp separation between different levels of of dynamics. Yeah. If you look at But brains. they seem to be like this in in their normal conscious states, they they sort of sit in what we call this subcritical regime where small differences can make

Yep. Differences at larger scales and and and and vice versa. So there's a lot of kind of dependencies across levels of description, which I think is is gonna turn out to be pretty important in understanding how brains do what they do, whether it's consciousness or cognition. Mm-hmm. Do you think I mean you were talking about

like evolutionary pressures to make the brain do particular things. Just more broadly, it might bring to mind the question of evolutionary explanations for consciousness. Uh like W when I've spoken about consciousness And people sort of just say, Well, you know, there's gotta be some evolutionary benefit. Like that's why consciousness exists, because by being conscious, you know, you avoid pain and you you're sort of doing things that help you to survive.

And two thoughts come to my mind when I hear this. Firstly If something is not possible, it doesn't matter if it's evolutionarily beneficial. You know, if if matter cannot produce consciousness, It it would also be very evolutionary beneficial if I could make two and two equal six, like when I wanted to. But that's not gonna happen even if it's beneficial, right? But more to the point, it seems to me That any kind of evolutionary service consciousness can provide Could also be provided by

uh unconscious reactivity by the sort of philosophical zombie type figure, or some some thing that doesn't have a complex brain that such that it produces experiences, but just that naturally moves away from heat, or follows the sun like a flower does in the garden without requiring this thing called consciousness. Do you think that there is a good evolutionary reason for consciousness? Given I I asked that in the vein of saying that I think it's kind of evolutionarily redundant.

You think it is evolutionary redundant or you think? It I think it is redundant. I I can't think of a of a service that consciousness would perform evolutionarily that couldn't be performed without inner experience being present. You know what I mean? Yeah, I I I get that. I I'm sympathetic. Mm-hmm.

to that kind of view though I don't know it to be the case. So i it it I still wanna reserve in part of my mind room for the possibility that there may be Certain functions, certain things that that could be evolutionarily beneficial. Mm-hmm. which do indeed require conscious experience, that cannot be done via unconscious mechanisms. Um I don't yeah, I I'm not sure if that's true, but I I don't think it's it's excluded. This doesn't mean that it's redundant in those cases where it exists.

Right. It may be the case. And I think so this is the more likely perspective fr from my point of view that Conscious experiences have functions for biological organisms. Yeah, I'm I'm not really on board with epiphenomenalism or th or you know it just seems like a very strange perspective. If we if we if we think about what conscious experiences are like in general,

they're easy to interpret in terms of having useful functions for us. You know, they bring together in the most general sense, they bring together a large amount of organism relevant information across many different modalities. in a sort of format, you can call conscious experience a format here, you know, that that is centered on the body.

that involves aspects of the body over time and that sort of immediately suggests opportunities for for action and and response um in terms of intentions and and urges and and and and so on. very counterfactual and empirically a lot of things that we do do seem to require consciousness. I mean this is the active empirical study of the difference between conscious and unconscious perception.

Yeah. So even if you can imme you can come up with a system which could implement these functions without being conscious. I think for the kinds of things that we are, for the living creatures that we are. evolution has sort of used the r the available resource of the potential for experience that living systems have um and drawn on it to to create expressions of consciousness which are functional for us.

You just said unconscious perceptions. Mm-hmm. I'm just intrigued as to what those are and how we study them if they're unconscious.

It's the family and friends event at Shoppers Drug Mart. Get 20% off almost all regular-priced merchandise. Two days only: Tuesday, April 28th, and Wednesday, April 29th. Open your PC Optima app to get your coupon. So this has really been one of the the workhorses of empirical consciousness research in neuroscience and psychology. You know, the idea is maybe you you you try to match as closely as possible The signals coming into the brain, the

but you try and create conditions where on one in one condition there's no corresponding conscious experience and on in the other condition there is. A classic example is something like, um Masking in perception. Yeah. So you can you know, you can show an image, but if you surround it with other images in the right way, then people don't perceive, don't consciously perceive the image in the middle. Mm-hmm. Um but it's still present, it's still presented to their visual systems.

So in that case, you might be tempted to say the perception was was unconscious. Mm-hmm. If you show an image really, really, really briefly, that might be the case as well. A colleague of mine, Axel Clearman's in Belgium, is he's he's developed a a tachistoscope, so a device very simple. It's just able to show images certainly m millisecond, possibly even microsecond, uh resolution. Right. Um

A more an example we use in our lab is we use something called continuous flash suppression. So we'd show an image. to one eye, and then in the other eye we show this kind of continually changing Mondrian of colored squares. And the person in that situation we'll only consciously see the change in coloured squares. Mm. Does it make a difference which eye you put it into?

Uh sometimes yes. If i people have dominant eyes, so i it can do. Yeah, okay. Um but the point is that you can you can create a situation where some sensory information is present to that person's brain and you can show that it, you know, it makes some kind of difference, yet they don't report consciously perceiving it. Yeah, I see. That's what I'm getting at. Yeah, I just I I don't know. I I I f I find To find out if someone has consciously perceived something

You kinda have to ask them, right? And I suppose I'm I'm just still a little bit like I've got a bit of whiplash from split brain patients and their ability to like draw an image that they've seen without telling you that they'll tell you no, I didn't see anything, but they obviously did'cause they'll draw it in their and with their hand.

And it that almost feels to me like when you when you ask the language part of their brain, their left hemisphere, did you see it? they'll say they'll say no. And if you ask the right hemisphere, it says yes by drawing the picture. And so I'm just I don't know, it makes me suspicious to the extent to which As long as someone says, No, I didn't see it, we can kind of count that as, so to speak, unconscious.

No, I mean you diagnize the the problem beautifully. It's it's it's a h it's a real really tricky area. Yeah. Um and there's still

very lively there's debate about whether anything counts as unconscious perception. Yeah, but right. What one of the issues th the thing you mentioned about verbal report is is absolutely key. And um You know, it could be that, as in a split-brain patient, if you verbally ask someone whether they consciously saw something, they might say no. But let's say you ask them to draw it or to push a button, something like that, you'll get a different response.

So there's a complication there. Typically in these experiments they require on pushing buttons or something like that rather than people verbally saying what what they saw and ways you can kind of counterbalance across hemispheres and sort of but it gets but yeah, it gets it gets really tricky. There's a conceptual issue here too, which is that It could be that. A conscious experience is still happening, let's say in your visual cortex, or supported by your visual cortex.

but that you don't have cognitive access to it at all. The philosopher Ned Bloch kind of argues for this possibility in this dis in this distinction between phenomenal consciousness and access consciousness. Which is the idea that cognitive access, whether it's through verbal report or pushing a button or whatever it might be, is is optional and you could still have conscious perception even without access to it.

That's really, really tricky to get an experimental handle on because if you don't have cognitive access to it, then how would you ever know that that it was going on? You've got to have some other other reason, other justification. Yeah, I'm

increasingly suspicious is the concept of the subconscious. I'm glad to hear you say that that's like a a normal thing that people are discussing because like I don't know. I think typically we think if there's something which What I call my like self, my my sort of reflective, uh linguistic, communicative self can't like access, we call it sort of subconscious.

But then I don't know. I think it depends on the degree to which you believe that consciousness must be centralized and smooth. You know, some people interpret this split brain related stuff, alien hand syndrome, all of that good stuff. As essentially showing that there are kind of two centers of consciousness that are in communication with each other in such a way that I guess you kinda just experience both at one time. And similarly to how like my eyesight

really sort of appears to me like it's one thing. Like I I I'm not sort of aware that I've got two eyes right now. It's only by sort of taking one away that I can kind of get a grip on it. It just sort of mixes together, but it's uncontroversial that I've got two eyes. There are two things seeing right now, but it's just sort of mixed together. Some people think that the brains are doing the same thing. What is your view on

They're like locus of consciousness. Is there one? Is there two? Is there many more? Is it sort of a a silly question to ask? I don't think it's a silly question to ask. It's a very, very hard question to answer. Yeah. Uh and there's a lot of debate about the unity of consciousness, which I think get gets at the at the heart of this. Mm-hmm. And the split brain case is is one of the key uh pressure points. Yeah. Um so

Some people tend to think of the unity of consciousness as being something axiomatic, that there can be only one, like Highlander. Right. Um Because it's very hard to imagine. too separate, you know. Consciousness being disunified. What what what might that even mean? It's not s much to say there's two A two conscious agents in in one body. I mean that that could happen in a split brain, that seems

possible. I mean the evidence is really mixed by the way with split brain patients. It gets very interesting when you look at it in in detail. It's like actually there's there seems to be problems with integrating things across the midline rather than detecting things at all. And there's all these subtleties about cross queuing. Like one half of the brain can see what the the other half of the body does and might make inferences based on

I would love to talk about that. I want to allow you to finish what you were saying, but I would love to talk about that. And But but yeah, to the to the unity point, I I think that if we so I always tend to try and Not be, I mean, I'm frustratingly non committal about these things. Like consciousness seems unified to most of us most of the time. I would not want to be.

build a theory that r required that to always be so because I think it might again be be right back to our discussion of human exceptionalism. Now there might be cases where conscious experiences become interestingly distributed, nonunified in certain ways. Octopuses give me a good provocation here where you know maybe their consciousness is decentralized. Um in a way that that just isn't the case for for animals like us who are highly cephalized. So Cephalized.

Well, we all our neurons are in the head and our neural architecture sort of div if consciousness evolved, if we think that's a useful perspective for us, it's evolved in such a way that w we experience consciousness from a particular perspective which is somewhere in our heads. What's that word? Cephalized I think it's a word. I think it means that most of our nervous system is inside, is in one place in in our head. She wonder where sephal comes from. Is that with like a C?

Yeah, C E P H. I mean some people say kethill rather than Cephel so Yeah, no, I've just not heard that one. That's it. Cephalopod. Which literally means brain foot. Oh. And they have more neurons in their limbs than in their Central. Like brain foot. Right. confused. I was like if we're whatever the word was cephalo cephalo or something.

Well w we have a lot of sufferization, so our nervous systems are concentrated in That's why I got confused because I thought cephalopods, but cephalopods don't have it concentrated. No, there's also the pod. Yeah, I etymology. I'm having Adam Alexic, the the etymology nerd on soon. I'll ask him about it, but um it's hardly, you know, either of our fields. Yeah, I I mean the first time we spoke on on this show years and years ago

uh we talked about the extent to which we experience ourselves as up in the brain as well. And I'm always sort of I sort of wonder, is that because that's where the brain is? Is it because it's where the senses are? You know, we talked about strapping a camera onto Like your belt. and then like putting on a VR headset and living

experiencing the world from from your belt buckle and and whether you would the sense of where you are would move down to to to your stomach. Um and I I kind of suspect that that maybe it would. I I'm not sure. But it weird to think about, like where I am, I feel unified, but at the same time I'm if as long as I pay attention, I can separate out the feeling of the chair from the visual experience that I'm having. Um I can sort of

I don't know, I can I can pay attention to the fact that maybe, you know, maybe I feel a bit hungry and maybe I feel a little bit like, you know, I'm a bit uncomfortable, I'm gonna shift position. And I I can kind of separate out those experiences. So I've never quite known exactly what it means to say that consciousness is unified.'Cause like true unity of conscious experience would seem to imply like

No delineation whatsoever, that's just experience. But I'm I'm I'm already being able to separate out various aspects of my consciousness. Yeah, I don't think it I don't think unity implies lack of differentiation of what's happening within consciousness. I think most uses of the term unity in in this context.

suggests that all of these things are happening within a unified conscious field. Yeah. You can pay attention to different parts of it and they can have different characteristics. But there's no sort of um the consciousness of your of of redness in the environment is is happening completely separately from consciousness of your other parts of your your visual field. It's all bound into into one. Sure. But yes, it has structure too. I think that's that's fine.

So talk to me about this uh evidence about split brain patience and consciousness because like the The pop science and pop philosophy version of this is like, whoa, how cool it is that if you take a split brain p patient who's had the connection severed between their two hemispheres,

their brains seem to act independently. You can show them a word to only one side and they'll tell you they didn't see it, but they'll be able to draw it. Um and some other really weird stuff, like you can I think like if you show somebody the words like I'm trying to think of an example here, but like um Uh it's not a great example, but like the word market and super, you know, and and they're on one side.

they'll sort of separate out the concepts. They'll they'll draw a market and then they'll draw some representation of super. Whereas healthy brains would put them together into supermarkets. Stuff like that's going on. Stuff like that. I mean a classic example would would be, you know, you you um It's but it's not each eye sa Yeah. Yeah. The left visual field goes to the right hand.

Exactly. But you can still talk. If you set it up rightly, you can still talk in terms of left brain, right brain. And so one thing you might do is recognizing that in most cases language is lateralized to the the left brain, the left hemisphere. you can show, let's say, an image to the left hemisphere, um, and then something else to the to the right hemisphere.

and then see what happens. And I think a classic example f right back to Mike Gazaniger and so on is that um you s you show something relatively prosaic to the to the left verbal hemisphere and then you show something kind of funny to the right hemisphere and the person starts laughing and then you ask them why they're laughing

And what they'll do is they'll kind of confabulate a reason why what was shown to the left hemisphere might be funny. Yeah. But it's got nothing to do with that. It's because there was something funny shown to the the other part of the brain. So there there are these amazing examples of dissociations. Of course the most amazing thing about split brain patients is that

Under almost any circumstances it's impossible to tell that anything's happened at all. I find this really quite quite astounding. You need these very specific experimental setups. But it does get a bit. um complex. Firstly, a lot of these things tend to resolve over time. Very few split brain operations completely segregate the hemispheres. These days they're not done that much because medication, thankfully, for epilepsy, has has improved.

uh a former postdoc of mine, now a professor at in Amsterdam, did a series of experiments on vision um showing that in a split brain patient, actually there they were each hemisphere was able to detect visual stimuli anywhere in the visual field. Mm. But what they couldn't do was integrate across it. So this is a bit like your supermarket argument. It was the integration across the midline that was that was not um possible. Yeah.

So I I still find it fascinating. One possibility Tim Bain, one of my colleagues, um, talks about sometimes is that it may not be a stable thing. Maybe maybe under some circumstances there's one agent and other under other circumstances there are two. Again, putting pressure on an assumption we might make, which is that the number of conscious agents hosted by a Yeah, by a skull has to be the same. Octopuses are great for that too, because like

their their limbs will kind of like do their own thing. It almost seems like sometimes an octopus's arm will go over here and then it will be like, Oh, you know, what's that? As if the th the the arm is informing the the brain. But if there's a predator that comes by, suddenly the legs all just like shoot into space in into place and and they sort of

swim away real fast, as if when needed, they can sort of act as one mind, but when not, they can sort of separate out a little bit. Maybe something similar goes on in the brain. You you said maybe some of these cases resolve over time. Well this is now I'm I'm kind of reaching very, very into the the recesses of my memory at the moment. But I'm I think you see the the strongest examples like the one of of the person laughing when you show something funny. I think these are most

prominent quite soon after after surgery. A lot of these things that the most fascinating about cases of of brain surgery or brain injury tend to sort of normalise a little bit. So another famous one is neglect where people seem to be unaware of what's happening on one half of their visual field after brain damage. That too tends to kind of ameliorate a little bit right over time. I see.

It d doesn't mean it's not real, it just means that it it's one of the reasons these things are quite hard to study. Yeah. Yeah. Does the other do you know about the Cranio Pagus twins? I don't think so. This is the other w it's kind of the opposite of split brain, which I think is is is almost more fascinating. Sure. Um so this is the case, you know you can get conjoined twins. Yep. Um so twins born

They cannot be separated. They usually join somewhere in the abdomen or the hip, so they may share a part of a digestive system or something like that or even or even a heart. Um there's at least one case of conjoined twins who share a brain. they cannot be surgically separated and and then they've been around for I don't know how old they are, but I think they're in the teens now. Um Wow. And what is going on there? Well what is it li are they are they are they individuals? Do they

They seem to be. Yeah. Yeah. So I I've I've never met them. I've only sort of read about them second hand. Yeah. Uh but they they seem to have somewhat different personalities but they also seem to share things, so one will be able to taste what the other one eats. Well For instance. Yeah, that's weird. Are they are they like aware of each other's thoughts? They seem to be, as you might imagine, extraordinarily synchronized in their in their behaviors. So it's I don't know

what their thoughts are but they in in and I've just seen these videos I mean I feel bad'cause I've this is just me watching videos of these things. But but they seem to complete each other's sentences. Yeah. So that seems to indicate that maybe they do sort of share at least the you know, the contours of a single thought. But then again, basically they're getting pretty much the same sensory input all the time and they have the same sensory experiences going back throughout their whole lives.

never know how to make heads or tails of of these people and in fact there's an interesting analogous question to be asked about AI, which I'll ask in a minute, but first just because it came to mind when you were talking about um showing one thing to one eye and and not the other. Um yeah, I I really like Ian McGilchrist and one of Ian McGilchrist's most important concepts is the concept of focus. And he says that focus isn't really it doesn't seem to be like a brain activity as such.

I don't quite know how he characterizes it, but he talks about how like if if I played two sequences of of like random numbers or words into each of your ears, so different sequence in each ear, and I just told you, just pay attention to the right ear. Then afterwards you could recite, you know, the the series of numbers, but you wouldn't be able to tell me what what the left one was. Whereas if I asked you to focus on the left hand side, you could do it vice versa. And that's the same.

just it's so it's extremely simple. Like, yeah, obviously, yeah, I'm focusing on one and not the other. But that just baffles me because I'm like, well, what's the difference? What is the thing that's changing. When I just decide to d I'm not moving, there's no new information really. There's no I'm just making this decision to to sort of I'm just I'm just pushing my attention over here and pushing my attention over there. That's the difference. Attention.

That just seems su such a strange like what what do you think attention is? Like i do you think attention is just a another kind of brain activity? Do you think it a a a sort of pre brain activity like uh qualifier as to how the brain activity occurs, like j you know what I mean? Like it seems weird for me to say that that attention or focus is just a brain activity because it seems to be the means through which I determine what brain activity happens. You know what I mean? Yeah.

W I think both I think that's it it would be strange if it didn't. I don't think would have the functional role that that it has. I think attention is one of those words, it's only slightly less mysterious than than consciousness. But I think it is less mysterious. I think it's less sort of metaphysically loaded. But it's one of those things that seems fairly natural, like I pay attention to something, but but when you ask what that really means, it gets very difficult very, very quickly. Um

Th but there are lots of of ways to study. I mean it's one of the classic paradigms indeed. As you said, you can pay attention to different streams of sensory information. And that will make a difference to what you can remember, to what you do, and and and so on, many things. Uh it is, I think. Uh something that's not. conscious experience. We're more likely to be conscious of things we pay attention to.

I don't think it's a a complete gate. You know, some people might take an extreme view and say we're only conscious of that which we're paying attention to. Right.

I think this is probably overstating it. Mm-hmm. But I think conscious contents have become dominated by by attention. And in the brain you can think of many ways that might play out. You know, the the more extreme views might take it as a sort of really strict gating mechanism that that only things you're paying attention to get through the gate and can influence other parts of the brain. I prefer to think of it using the the overall framing of this brain as a prediction machine idea.

that attention is i firstly it's not just one thing, it's many things. It's kind of many ways of adjusting the sort of the gain, the signal to noise ratio. Mm-hmm. How much does the brain update its

inferences about what's going on based on some sensory data. Paying attention to something is equivalent to saying This sensory prediction error, this piece of sensory information is is worth uh well, I was gonna say worth paying attention to, but that's a bit circular, is going to have more of an impact on the perceptual inference.

on this sort of continuing unfolding process of prediction error and prediction error minimization. Yeah. So on this point of the unity of experience. I mean, let's go back to the topic at hand that you have written about and has obviously caught a lot of attention and impressed a lot of people and and won a prize for for its eloquence. Um well, I say for its eloquence, also for its, you know, scientific and philosophical rigour. Uh and that's AI consciousness.

And we've just been talking about how sort of weird it is to think about where the locus of the locus of focus is, where unified conscious experiences might exist and how they interact in

We we were on a panel hosted by Brian Cox, A Question of Science, which was it was good fun. It was a little um I remember sort of walking in and and br and Brian sort of being like, uh, oh, you know, let's not let's not talk about this pan psych and stuff. And I was like Okay,'cause I'd never met him before, so I was just sort of like, Hey, um so

Gonna gonna maybe gonna maybe do that anyway if that's all right with you. Uh it was good fun. Um and one of the things that I said and it was kind of tongue in cheek and I I didn't mean for people to laugh, but they did. Uh But it's got a serious point in it, is like, when we talk about AI being conscious, what do we really mean? Like I know you kinda think it's probably not gonna happen, but the thing you're imagining is not happening

I'm like, what really are we talking about? Okay, so ChatGPT becomes conscious, cool. But as I said on this panel You've got ChatGPT on your phone, maybe. I've got it on my phone. It's on we've all got our own sort of accounts. I'm having a conversation here. Even within my account, there are multiple streams of conversation. And yet at the same time You know, like open AI is like

software and and computing power is not stored in my phone. It's stored somewhere else and my phone is connecting to it. And I I I'm like, what would it even mean? Would people sort of imagine Each individual conversation is like a new conscious being waking up.

unaware of the other ones? Or is it like a conjoined twin where they're they're they're their own thing, conversations, but they're kind of connected and can kind of interact with each other? Or if they're like one chat GPT consciousness that exists wherever OpenAI, San Francisco, whatever is is is based and we're kind of interacting with avatars or like as if the conscious agent is like sending messages back and forth. How how can we even think about what it would look like?

I think this is this is a great observation. It's um David Chalmers has written a nice piece about this. I think it's called What We Talk To When We Talk To A Large Language Model. Nice. Um and On the one hand, I think all the things you say just highlights the trouble we get into if we get captured by the f this the superficial fact that these things are linguistically competent. Mm-hmm.

under the hood, they're massively different. And it's not only now a question of silicon and algorithms, but also, yeah, w is there an identity? What is the identity over time? What what's actually talking to you? Is it

Is it it's not the foundation model,'cause that's stable. Is it an instance? Is it a server farm? The server farms Yeah. You can put a query in, it could be processed in Arizona. Yeah. Half in Arizona and half in New York and maybe the other way around the next the next time. So it's what's stable? Also, and I think this is key, you can leave a conversation for a day or you know, a year. Right.

back to it. But you come back to it. Yeah. And from the seeming perspective of that conversation that doesn't make a difference, yet time Time is fundamental both to how biological brains work and to our experience, to the nature of of conscious experience for for human beings. So seen that way, I think noting these differences. just should highlight the danger of reaching assumptions about AI consciousness on the basis of their fluency with language, their ability to pass the Turing test.

But on the other way, I think it's really valuable to sort of set aside at least temporarily not forget about, but temporarily set aside the question of whether they are in fact conscious and ask exactly how you put it. For the sake of argument, let's let's just ponder what it would be like if they were. And I think in doing this, We can we can probe at all these issues like the unity of consciousness.

that we take of as th that that we that are so hard to get out from underneath of in the human case. Yeah. And and then maybe, you know, it it sort of gives an insight into The a wider space of possible minds. These minds need not be conscious minds, but There is very likely a very large space of possible kinds of minds. And we are in one sp region of this space. Maybe biological minds in general are in a larger space.

But they are still somewhat constrained by the fact that biological minds evolved within bodies, probably almost all of the time. Maybe think about fungi or something like that, but most of the time. But there may be other kinds of minds. Which don't have those constraints, which could be very different. And the comparative approach is always useful. And I think we can do that. without making any imputations that these strange new minds need experience anything.

Yeah. I mean I think that i the extent to which it's difficult to make sense of what we would even mean by conscious AI could be an indication that the thing we're talking about is like

A little bit senseless, maybe. Um but it's also going to depend on what your theory of consciousness is and what your sort of hunch about the nature of of consciousness is. And you said earlier that you believe in this idea of the controlled hallucination which you've

talked about a bunch and you talk about it in being you, your book, and I suppose it might just be helpful for people who are hearing you for the first time on this show to just briefly sort of overview where you're coming from when it comes to consciousness before you start thinking about AI. Yeah. So the the overall perspective I have on consciousness is to be very pragmatic, really. Like I

when asked, I describe myself as a pragmatic materialist. I don't know that materialism is true and I I don't want to be a person who is who's sort of out there on the front lines defending materialism against all karmas, but I think it's a useful I've always found it a useful perspective to adopt because it gives us the resources

to at least chip away at the problem of consciousness. And by chipping away, I take something like this what I call the real problem approach. So, you know, consciousness exists, phenomenal realist. It has many different properties. Vision is different from emotion is different from Um audition is different from memory and and so on.

What I'm interested in is a kind of unified way of thinking about different kinds of conscious experiences that explains their relation to each other, that explains their character, and that

progressively might explain something like their dependence on a particular kind of substrate, whether it's biological or or not. The controlled hallucination view is is an expression of this. It's really a a gloss on a pretty old idea, which is perception as inference, which goes back to well, in philosophy back to Kant at least, and the idea that there's a numen and a phenomenon, and then in psychology to Hermann von Helmholtz He was the first person to talk about

Perception is a process of unconscious inference. So the brain is engaged in trying to infer the causes of sensory signals, but all of that goes on under the hood. It's not even unconscious perception. Those are the unconscious processes that underpin Perception. And what we're aware of is the brain's best guess, the brain's most what the brain comes to as the most likely

Interpretation of the causes of the sensory signals that it gets. That's why I call it a controlled hallucination. Um and it kind of flips. what used to be the textbook view of perception on its head. You know, it's it's classical to think about perception as a process of reading out the world. Yeah. In this outside in direction. Information comes into the eyes and is read out by the brain and you get deeper and deeper and it reads out more and more complex things.

This view goes the other way and it says the content of our experience, even though it seems to be out there and we sort of passively register it, no, we actively generate it. And the sensory signals are used to calibrate these predictions so that they're useful for the organism. Yeah. And some of the classic examples of this are things like The the checkerboard illusion, you know, which Alex will put up on screen right now. And uh it's you know, the the two squares which look

Like they're different colours, but square A and square B on your screen are the same colour. And you can prove it with various ways and if you don't believe us, you know, take it into Photoshop and check it, whatever. Um and even when you know that You see them as different colours because your brain is essentially constructing a narrative. Like why why would you want to perceive them as as, you know, the actual

shade of the of the pixel that's lighting up on your screen. It makes sense for your brain to interpret the world in a way that makes sense narratively. And so there's a sense in which, yeah, we are constantly generating the world. We the first time we spoke on the show, we talked about like the audio illusions, the Yanni Laurel thing, the brainstorm Green Needle thing and

it some of these like whichever one you're like looking out for or listening for is the one that you hear. Like you're literally able to construct your perceptual reality. I feel like every time I've heard you talk about the controlled hallucination, I've I've come a bit closer to kind of understanding where you're coming from. But at the same time underlying all of this for me. It's this presupposition that there must be experience.

Right. Like I think if you say there is this thing called consciousness Now let's talk about like what it's doing and what its nature is. Like, yeah, there's lots of evidence to suggest that we're sort of the consciousness is as much outward as it is inward. That's cool. But Do you see this controlled hallucination view as also like an explanation of what consciousness sort of is in the first place, or just why, granted the mystery of it existing at all, it presents itself in a particular way?

Much more the latter. Yeah. I don't think it really tells us what consciousness is. Now I have this this ongoing discussion with with panpsychist philosophers like Philip Goff, who I know you know. And he will always say to me, in fact I saw him last week, he will always say to me things like, Everything that you, you know, you materialist oriented scientists come up with about the brain and its relationship to consciousness is completely compatible.

With something like panpsychism, probably compatible with with idealism and and other things as well. And I think that's probably true. I have no reason to doubt it. Uh-huh. But the question for me is. is a pragmatically materialist view. Well, I don't know what what things really are. I mean, as you said many times on on podcasts with with guests that you know, you can take a chair apart, you find molecules, you take mol molecules apart, you find atoms, you take those apart, protons.

Quarks, quantum fields. What what ac what actually is Yeah. Right. Is something I'm certainly not qualified to answer. Is it is it mental states? Is it stuff? That has in addition to physical fundamental properties, mm-hmm, qualitative conscious properties as well. Um I don't know. But the thing is, I think a pragmatic materialism that says at the li level of analysis that we currently

are interested in, or I am interested in, which is brains are made of stuff. And I tend to be more interested than most people in in what they're made of too, and not treating them again as just computers that happen to be made of meat. Um Am I am I moving the needle on explaining properties of the phenomenon? Mm-hmm. Or am I barking up the wrong tree entirely and making matters worse? Yeah. So Imagine a a kind of controlled experiment. You take a bunch of

of uh scientists who who have uh a sort of panpsychist outlook. Mm-hmm. And you take another bunch of scientists who have a materialist outlook, both sort of pragmatically held, just Yep. They don't really know, but that's their predilection. And then you let them loose to construct their theories and do their experiments. And then you come back in fifty years. Yep. And you see from some view from nowhere, metaphysical view from nowhere.

which group has come up with uh m better again, criteria not defined, better accounts of of consciousness, made more progress. Mm-hmm. I don't know the answer to that, but my suspicion is that at least from where we are now, We get further. with a materialist outlook. Mm-hmm and I mean this what I certain and and why do I think that? Well, this whole view, for instance, of perception as controlled hallucination goes some way to articulating that. You know, we start with a view that

our experiences some sort of outward in reado, and then we realise that maybe something to do with internal generative models and prediction. And then we realise that that's that principle, which is based on a sort of materialist account of neurons Um and they're dynamic. we realise, oh, we can understand emotion through those same principles. We can understand the experience of free will.

within that same framework, we begin to draw together apparently disparate phenomena in ways which have a a kind of inner coherence and which have predictive and explanatory power. Mm-hmm. we may still come up short, and in fact we do come up short when addressing, you know, the question of well, why is there consciousness at all? And but but we understand more about the phenomenon. And for me

I wonder whether the more we do that, the less perplexed we'll become about the the fundamental mystery that the different metaphysical frameworks are trying to to grapple with. Yeah, maybe. The reason why I've been sort of unconvinced, unimpressed by this this view of consciousness that you have is maybe because of the fact that I'm sort of I'm mistaking what your what your project is. It's a little bit like You know, if we were talking about music, you know, there's a piano over there

And you could start playing major chords and minor chords and you could start talking about like how music works. You could start saying that there's like a harmonic series and like there there are kind of you know, you could do it in terms of strings like Pythagoras and there's there are sort of vibrations and Yeah, the the the ones which are the right

sort of uh frequency of vibration compared to others creates the happy sound and the sad sound. And you can talk about all this stuff. You can talk about artistic input. You can talk about how playing various ways produces different sounds. And you could do all of that and have this whole music theory. You construct the whole of the the like any musical theoretical canon and never once

have needed to know or address the question of like, well what is music? Oh, it's it's vibrations in the air. That's what's actually happening. Is like, you know, the air is being vibrated and that is hitting your eardrum. You wouldn't need to even address that. to have what some people would say is like a theory of music, you know, a complete, robust theory of music. But I wanna know, you know,

What's causing that musical note? I want to know that it's vibrations in the air. Right. And I feel like with a lot of so-called theories of consciousness, they're like these theories of music that don't address what the music actually is. And I wonder the extent to which you see your view of consciousness as being one or the other, or both, or whether you would say that you're sort of leaving that question of what it actually is to the side.

I think there's a you know, if I was gonna be unkind to myself, it's a sort of kicking the can down the road. Right. On on that question. But I don't think it is quite like that because I think the road changes and the can changes. Yeah. As as you do this. And this is Because

What we think of as the the mystery of of consciousness is is a bunch of related mysteries. There are things like what does free will exist? What is the nature of free will? Things like that. I think the more we can sort of dissolve those mysteries or wrap them into a single framework, a single approach. we we do make progress. I also want to know How do we fit consciousness into our a fundamental view?

of of the universe. I don't know what actually exists. You know, I I I think that stuff exists, but what stuff is, I I don't know. It may may all be mental states. I don't know. But I think there's the kinds of theories and experiments and explanations that we can construct. come about mainly through thinking Through following the sci the scientific method in general has been about explaining phenomena in terms of the physical attributes of things. Mm-hmm.

Even if those physical attributes turn out to be non fundamental in some way, there is a suspicion that this will not work when it comes to consciousness. Mm-hmm. And I just I'm suspicious of that suspicion. Yeah. You know, I I wanna wait and see and see what's left, just as in we might strip away all the contingent aspects of conscious experience. Let's strip away.

all the answerable questions about consciousness that follow from thinking about its relationship to what we think of as physical processes and see what's left. Maybe there will still be a very deep residual mystery.

But maybe there won't. I mean the historical analogy which I use with caution here,'cause I know it's imperfect, is life. Yeah. Right. That life was considered Uh well, I mean, beyond physics and chemistry, that there may have to even be something non naturalistic, which seems strange talking about life, but something supernatural, Elon Vital, something not accounted for by the laws of nature as they were.

And of course we don't understand everything about life, but that sense of mystery has receded, and we can now see that many things we think of as as as definitional of life can be accounted for through biochemistry, physics, so on. Yep. Quantum mechanics to some extent as well. So the sense that there was something incredibly resistive

to this kind of explanation didn't persist over time. Now life is not the same thing as consciousness. Consciousness seems to have this different mode of existence. Yeah. But

aspects of it are kind of describable. We can describe different kinds of experience. We want to answer questions about which kinds of systems have consciousness at all. And I think perspective of of understanding how consciousness in humans is related to the physical systems that we are, and then generalizing bit by bit outward. is the right way to answer these kinds of questions. And back to AI. You know, we we need to come up with a way of talking, a way of thinking about

Is AI conscious? Because that underpins a lot of moral and ethical decision-making. It's already affecting policy and and people's behavior. And from a materialist a lightly held materialist view, you know, we can start from the assumption that it is something about there's something about the materiality of an embodied embedded human brain that matters. Maybe it's the computation, I doubt it.

Maybe it's something else. We now have a research agenda about okay, what aspect of our materiality matters and and why? And I think coming up with Justified, testable. Examinations of that question, hopefully answers to it, will help us say the things that we we really need to say about AI, but also about non-human animals, about all kinds of situations.

So maybe this does speak to the fact that that there are slightly different agendas here. I think a science of consciousness really needs to address itself to these immediate questions as well as the ultimate questions of what consciousness really is.

Yeah. Well, the essay is The Mythology of Conscious AI. It'll be in the description. Congratulations again. It's a it's a great read and it's it's well needed, I think, because there isn't much in the way of like level headed, let's say, discussion about AI and sort of trying to calm people down on this front and not from the perspective of like, you know,

avoiding doomerism and the AI takeover and terminated robots, just sort of put that on the shelf for a moment. Let's just think about computation, consciousness, how it all works.

It's uh it's it's fresh air. So I'll make sure that's linked in the description. As well as B and you, your book's been around for years now. We talked about it the first time we met, but there's there'll be more in there on the sort of controlled hallucination related stuff. And also, thanks for coming back. It's been fun. Thank you, Alex.