In Our Time - Consciousness

Episode Date: November 25, 1999

Melvyn Bragg and guests discuss the problems of consciousness, one of the greatest mysteries facing science and philosophy today. The frustrations, the stubborn facts and the curiosities of today’s thinkers, philosophers, physicists and psychologists, demonstrate the elusiveness, and the utter impenetrability of consciousness. Can we explain our perception of colour, smell or what it is like to be in love in purely physical terms? Can memory, conviction and reason be explained primarily in terms of neural firing sequences in the brain? Three centuries ago Descartes famously believed that the problem was best solved by being ignored. Was he right? Could it be that the human mind is just not built to understand its own basis?With Ted Honderich, philosopher and former Grote Professor of the Philosophy of Mind and Logic, University College, London; Sir Roger Penrose eminent physicist, mathematician and author of The Large, The Small, and the Human Mind.

Thanks for downloading the In Our Time podcast. For more details about In Our Time and for our terms of use, please go to BBC.co.com.uk forward slash Radio 4. I hope you enjoy the program. Hello, one of the greatest mysteries facing science and philosophy today is the problem of consciousness. Can we explain our perception of colour or smell or what is like to be in love in purely physical terms? Can memory, conviction and reason be explained primarily in terms of neural firing sequences in the brain? Three centuries ago, Descartes famously believed that the problem was best solved by being ignored. Was he right? Could it be that the human mind is just not built to understand its own basis? With me to try to unravel the complexities of consciousness are the philosopher Ted Hondrick,

recently retired from his post as Grote Professor of the Philosophy of Mind and Logic at University College London, and the eminent physicist and mathematician Sir Roger Penrose, author of, amongst many other books, The Large, the Small and the Human Mind. He's the former Rouse Bold Professor of Mathematics at Oxford. Is it possible, elliptically or briefly, to say what consciousness is, Roger Panneras? Well, that's a difficult question. But I mean, by consciousness, I would tend to mean basically awareness, but also that's the sort of passive aspect of consciousness,

but also free will, whatever these things mean, I would say is included in sort of the active aspect of consciousness. but basically being aware it's hard to define because I don't think we really know what it is yet. Well, that's... Ted Honrick? I think consciousness is at bottom

something you can call perceptual consciousness. That is, being aware of the room you're in or perhaps aware of the car you're driving. And if one asks the question, what is it to be aware of one's surroundings, what is it to be perceptually conscious? I think the proper answer is essentially this. it's for a world in a way to exist.

It's for a world in a way to exist. That answer isn't this one, that the world exists and you're somehow aware of it. Rather, the claim is that what it is to be aware of a world is for the world to exist. That's my own view and not popular, but it might be true anyway. Roger Penrose, why does this consciousness,

why is it so fascinating for both philosophers and science, I think it's something that people have been, of course, interested in since we begin to think about things at all. But I think the main question is why scientists have become interested in it. And I think it is a bit of a new phenomenon that scientists have taken this subject seriously. I think it's partly a matter of being able much more accurately to tell where different things are happening in the brain, are these techniques like PET scans and so on, which can pinpoint. thoughts, things of that sort. It doesn't tell us much more,

because to know where something is happening, doesn't really tell us what's going on, which makes the phenomenon of being aware what is it that does that. What sort of pinpointing, to be more specific for our lessons, what sort of pinpointing would you give us an example of scientists developing in this area and therefore thinking they can have an interest in this area?

Well, there are certain very clear-cut things like perception of motion or perception of colour, which are in two quite different parts of the brain. I mean, this is one of the big puzzles that neurophysiologists have about understanding how it is we form a mental image of something because the different ingredients to that mental image

are involved, different parts of the brain are involved, and they can be quite different, in quite widely separated regions on the brain. But yet one doesn't have this somehow image of different things separate. So there's this problem of how we form one image. But the fact that these different aspects of an image are in a sense registered in different parts of the brain

is something that's known now from these kinds of scans that can be done. Ted Honrick. Could I promote a certain distinction, which I think is very necessary here? There's the question of what consciousness is, first of all, and it's the one we began with and gave our initial answers to. and there's the question of what the basis or explanation or cause of consciousness is. And that second question is, of course, a separate one. Now, many people believe that the basis or cause or explanation of consciousness is in the brain,

and indeed in particular parts of it, which are well studied. I wasn't quite clear whether Roger Penrose had the view that not only the basis or cause of consciousness is in the brain, but also had the view, perhaps slightly more remarkable, that consciousness itself is that stuff in the brain, that is essentially electrochemical activity. That second view is perhaps less attractive than the first, sometimes called eliminative materialism, and usually held in places of strong sunlight.

You really are going a bit too fast for us. You've got to take this one, well, I'm going to take this one stage at a time. You'll maybe have brilliant listeners out there, but just one point at a time. Do you want to reply to the first part of that, Roger? Well, let me say, I don't think it's electrochemical processes in the brain. Let me just, I mean, I could say a bit more what I do think it is, but that's certainly not my view.

I think we're a long way to go before we know what's going on. So I think there's something quite different from ordinary physical processes involved. Can I go back for one moment here? Can you tell us about the theories of functionalism, which were one way to understand the modern understanding of consciousness, as I understand it, following on from Gilbert Ryle's book in the middle of the century, middle of this century, concept of the mind,

initiated behaviorism and then functionalism, which became an idea, a way of looking at it. If you could tell us what that was and where it got to. I take it that functionalism might be thought to have its origin in certain truisms. If you tried to explain, say, what a desire was, a desire in general, it would be impossible to leave out that desires are owed to or spring from perceptions or input, and they give rise to behavior or output. The desire for a glass of wine is, very typically, the effect of seeing the man with the tray of glasses, and it's the cause of one's arm going out to grasp a glass. So an adequate conception of a desire would include the input and the output. Functionalism takes the radical step of saying that the desire is no more than whatever is in those causal or possibly logical relations.

It's just the state that is the effect of certain input and the cause of certain output. So love is a series of bodily movements, for instance? Well, functionalism is yet more, so to speak, elusive than that, because what, makes the thing a desire is that it's in those relationships. It needn't be neurochemical and it needn't be silicon and it needn't be anything. Whatever is in those relations, that is, whatever functions in this way is a certain kind of effect and a certain kind of cause is a desire. And more generally, conscious states are things that stand in these causal or indeed logical or computational relations.

That roughly is functionalism. Thank you very much. Roger Penrose, you, of course, you're a physicist and you're coming at consciousness from that point of view. But you've, so far, you've been, as you said publicly, well in your books, you've been disappointed.

Because you've spoken of a missing physics. You've said that physics can deal marvelously with the big problems, Newtonian physics, there's a tiny, tiny problem from quantum physics, but there's a missing physics. First of all, what's that? And secondly, why should that have the answer?

Well, I think there are two separate issues here. One is that it has nothing to do with the mind, or at least it doesn't have to have, namely that there is something missing, fundamentally missing in our physical picture of the world. Now, this just comes from physics. And the thing that I regard as missing is the sort of bridge between the quantum level, which describes how atoms, fundamental particles, molecules behave, and the large-scale classical level, which describes how cricket balls behave. And there is a sort of stopgap way in which this is treated at the moment. But I think this is just a fudge and that we are going to have to have some new physics which bridges that gap. And I just think it's missing.

Now, whether that has anything to do with consciousness, of course, is a separate issue. And I think my main reasons for believing it has something to do with consciousness or that consciousness depends upon it, put it like that. I don't think it answers the question of what consciousness is. but I think consciousness depends upon this missing ingredient. And the reasons come partly from the belief that the two levels of physics that we do understand, the quantum and classical levels,

are basically computational. So there are things that we could simulate on a computer as we understand computers today. And I have strong reasons to believe that our conscious thinking is not something of that character. So if we believe it's physical, we have to look to something which is not in our present physical worldview. And the most likely place is this gap between the small and the large scales.

And you've talked about microtubules being a possible key to understanding. Yes, and again it's a somewhat negative argument in the sense that I don't see any role for this gap being sort of relevant in ordinary nerve signal propagation. You have to look down more deeply into smaller structures, more organized, structures, things of a more crystal-like nature, which could possibly support the quantum level, and you need to go both sides, if you like. You need something which could support quantum level activity and something classical so that you can make use of the bridge between the two. But it is a somewhat negative argument. Yeah. Ted Hon. What do you think of this argument? Well, I'm afraid, Melvin, possibly to your irritation, I would like to go back to the two questions,

which I wanted to separate. I was just trying to sort of get a cleaner line. And the two questions are, what is consciousness? And secondly, what is its cause or basis? And they are distinct. Now, it's very unclear to me whether Roger thinks consciousness is microtubules or microtubular activity, that is neurophysiological activity of some sort, or whether he thinks that that neurophysiological activity is the basis or ground or cause of consciousness. Now, if he thinks the second thing, that is a fairly conventional view,

a version of the thought that consciousness is somehow based in the brain, but doesn't give us any answer to the first and fundamental question, what consciousness really is. Can I perhaps comment? So I think the important thing is we need to know more about what the world is like. I mean, when you ask questions like what consciousness is, we don't even know what an electron is. I mean, until we know better what the physical world is like,

we're not going to know how we can fit the phenomenon of consciousness in together with that physical picture. So I think I have a feeling that you're looking at this rather, if you like, an old-fashioned way in which physics is viewed. We're going to have to know more about the physical world before we can attempt seriously to answer this kind of question. But still, could I ask the question once more? You mentioned microtubules, which are,

there are a neurochemical fact. Do you take consciousness to consist in them or to be based on them? No, the microtubules are just a vehicle. I mean, they're not the important phenomenon. The important thing is to tap into something in the physical world which is much deeper than those things we know about the physical world already. We have some feeling about the quantum level of the world. We have some feeling about the classical level of the world.

we have almost none about the bridge between the two. And I believe you need to tap into that bridge in order to sort of manifest consciousness. Can I ask you, Roger, you've always claimed that consciousness can't be simulated by computers. Given apparent advances in artificial intelligence, why you feel so strongly about that? What's your evidence?

I think there's more than one piece of evidence there. I mean, computers certainly do wonderful things, and of course one famous example is Deep Blue in its chess match against Garra Kasparov, where it did win the match. Lucky it might have been, but it did win the match. However, there are chess positions which you can give to Deep Blue

and it simply makes completely stupid moves. And you can understand why it makes this stupid moves and you can understand what the right moves are. And the reason is it has no understanding. I would say that the word understanding more or less characterizes what I regard the things that computers can't do. They don't have any understanding. You can see why they do well in the tasks that they do well.

It's human understanding that is being applied again and again and again and again, but there's no understanding that the computer has. So that for the computer model doesn't take your very much. You use the example of children's grasp of natural numbers here, don't you? Yes, I think that's rather good example. The trouble with chess is that it's a finite game, and you could ultimately design a computer which by brute force computation could do as well as you like, in principle. I mean, it's beyond present-day capabilities.

But in mathematics and the natural numbers, just zero, one, two, three, four, and so on, is an infinite family, and there is no way to encapsulate all the properties of the natural numbers simply in terms of rules or mechanical procedures. and that I think reveals the phenomenon of understanding more clearly than something like a finite game like chess. Does that help in the search for consciousness, Ted Honour? I'm afraid it darkens the scene absolutely in several ways. Roger Penrose has an idea that somehow understanding or insight

is going to be particularly enlightening with respect to the subject of consciousness. and I fail to see that. If one thinks about organisms from the amoeba up, at some point, consciousness becomes a fact of such an organism. A very low-grade organism, but it is conscious. It's a long way off the understanding or insight or whatever, which Roger Penrose associates with consciousness. That's one point.

I have another, but maybe I'll wait for that. No, that's one at a time. It's easy. In this sort of linear discussion, it does work better, yes. Have you answered that? Yes. I think there's a misunderstanding here. I'm not saying that this is the only manifestation of consciousness.

I mean, the perception of the color red is a manifestation of consciousness. There are all sorts of things where consciousness is involved. I'm just not talking about those particular things. And if I want to show that something lies outside computation, then if I can show it in one example, then that's sufficient. That means that you can't do it with computation. Now, I just think you can't make a computational device perceive red either, but that's not something where I can apply mathematical arguments.

So I'm certainly not saying this is the characteristic of consciousness, that consciousness is only understanding. There are many other aspects of consciousness, certainly, but it's the only one I can get a handle on and to show that it is clearly, from mathematical argument, something outside a purely computational activity. Well, take us to your next question? I remain baffled about what Roger Penrose thinks consciousness is,

but let me say just something about computation and computers. Certainly it's the case that present computers only compute, but I think Roger Penrose also holds the view that mechanical devices or artifacts couldn't do this other she-she thing that is understanding or insight. It's not at all obvious that you shouldn't have a mechanical device which did that, non-computationally.

And indeed, I think he actually allows that in his book rather late on, in which case I'm not quite sure why he's so condescending about the poor computer. The, to have a device which behaves non-computationally would have to build it out of something we don't know about how to do at the moment. Ordinary, I mean, that's part of my argument. If you use simply classical physics, some use cogs and balls running around, things like that, that wouldn't do it. If you use purely quantum end of things,

that wouldn't do it either. So this is the reason I say you need something beyond the present physical picture. Can I go back just a little bit in order to go forward? There have been lots of people writing it. We mentioned Descartes, well, far too briefly. Hobbes' idea that there was no fundamental

difference between our minds and our bodies. Is that a view which has any sort of currency at all today still, Ted Honore? Well, it does have currency in Southern California and Australia, those places of strong sunlight, which may affect philosophical reflection. That is, there is the view that the mind is nothing but the brain, where that means that consciousness consists in nothing but electrochemical activity. But it's very much a minority view. Functionalism, the view that you mentioned earlier has, so to speak, replaced eliminated materialism,

but seems open to as serious objection as eliminated materialism. That is, we intuitively say both of those views leave something out. If somebody says consciousness is merely electrochemical activity, we're convinced that they've left something out in their account of consciousness, and so with the functionalist picture, I might add that if it turned out at some future date that micro-tubules in the brain were identified with consciousness, or their stuff was said to be consciousness,

we would feel as strongly that something had been left out. But since Roger Penrose refuses to say whether he's characterizing consciousness in terms of this stuff or merely saying that consciousness is based in this stuff, I don't know whether that point applies to him. I think I've never claimed I know what consciousness is. And I think the program is to try and understand what consciousness is through various reasons,

okay, philosophical arts, argument, logical argument, mathematical argument, physical argument, psychological argument, and so on, neurophysiological arguments. But I'm not saying I know what it is, so I don't think it's fair to ask me this question to define it or anything like that. I don't think it's microtubules, that's not the point. The point about the microtubules is that they're the best bet that I know of in making use of the various aspects of physical world that I think we're going to need to be.

to call upon. Ted Honour, can I ask you, do you think that physics at the level practiced by Roger Penrose and people has got absolutely nothing to offer to the philosophy of consciousness? Because you seem to be banging down on it all the time.

I mean, I'm an outsider, I'm in both of the impression I'm getting, do you think there's nothing to offer? Do you think that the mind is not available to the sort of investigation, which Penrose has claimed no more than investigation,

that he is conducting, that is something that philosophers can discuss, assume, take us that agenda, which is the agenda of themselves alone. I think I thought with just about everybody else that consciousness or mental activity, let me simply say consciousness, is related to the brain. That is part of the explanation of somebody's being conscious is brain activity. And indeed this is a well-held and well-researched view. But while it's the case that physics will contribute more and more

to that account of the basis of consciousness, I think nobody thinks that consciousness consists in electrochemical activity. Roger Penrose doesn't say so. So if it's the case that consciousness is other than brain activity, then no matter the amount of science that goes into investigating brain activity, you won't have got a conception of consciousness from it. But you seem to me to be very close to saying that no matter, that can be discussed or described can describe consciousness.

But it is not something that we can, that can be discovered through a discovery of matter. Whatever matter, however tentatively Penrose has put forward as a possible explanation for consciousness, you say, well, no, that doesn't get us anywhere. I think that his view is, his view, well, I'm not quite sure what his view is. It's a little hard to pin it down. But I think of you...

Well, the fact that it's hard to pin it down part of his view. Yeah. Well, maybe ought to have pinned it down before he arrived for this discussion then, or before he wrote his book. No, no, no. But does need pinning down. One's allowed to have honest doubt in religion.

I don't see if I shouldn't apply to physics as well. Well, honest doubt is all right. I mean, I'm very happy that he should have honest doubt, and I certainly have honest doubt about his views. But it is, it is. You have any honest doubt about your own views? It's a matter of interest. I have great honest doubt about my own view,

but let me tell you what the view is, and perhaps you'd like to bat it around. a little bit. All right? Sure. If you ask me what it is for me or Roger or you now to be conscious or conscious of this room and we reflect on that and we all do have a grip of what it is, we all think incidentally that it's got a lot to do with the brain, it seems to me that the most persuasive first answer you can come to is that what it is for me to be conscious of this room is for this room in a way to exist. Yes?

Now, you're perhaps likely to hear that sentence in a way which suggests something like this. I'm not making any advance. I'm not giving any analysis of what it is to be conscious of this room because I'm merely saying that a world exists in some metaphorical sense. And so there's no real explanation of what consciousness is in talking about the existence in a way of a world. and I would like to dispute that, and it's the center of my view.

If you think of the physical world, according to one conception, or the physical or the objective world, it consists, as I think indeed Roger implied a while back, it consists in atoms and sofas, roughly speaking. And the sofas are in space, and they are perceived by us, and the atoms are in space and not perceived bias, but they are causal with respect to the sofas. Now, if you think of the perceived part of the physical world, the sofas, that world, in a sense, depends on our perceptual apparatus. Bats, for example, don't have the capability of having an appreciation of the visual properties of the world.

So the physical world in its sofa part depends on us generally. And if you now go back to the world of perceptual consciousness, my world of perceptual consciousness, that depends on me. But the fact that it depends on me shouldn't turn it into a mental world any more than the fact that the perceived part of a physical world depends on all of us, our perceptual apparatus, turns that into a mental world.

So I really want to say that the answer to the question of what perceptual consciousness is is that it consists in the existence of a world which has a particular dependence on the perceiver. Do you think that that explanation allows your investigation to continue in the way you're sitting about it? Or does it run contrary to what you're finding?

I think I have more trouble understanding Ted's view than he is having understanding mine here. I really don't understand. I don't see how you can explain what consciousness is from somehow. I mean, you seem to be attributing the existence of the external world to our consciousness of it,

which I don't think you're saying that, are you? But it's the way it sounds. What about different individuals? So you've had two or three individuals, all perceiving the same sofa. Are there several sofas, or is there one sofa? If there's nobody in the room and there's still a sofa, is there still a sofa there? If one asks the question, what is it to be aware of this room? And I answer, it's for a world in a way to exist.

That world depends in part on the perceiver, and in part on that other world, the world of atoms, the physical world in its other part. It has that dual dependence. What do we bring to bear on our? perception? What is our perception? What is the stuff out of which our perception comes? Is there stuff? And if there is stuff, why can't Roger Penrose's investigation be getting somewhere near it? Can you answer that, Roger? Because I know. Well, yeah, well, go ahead. I mean,

if you can see something about it. Perhaps this mayor may or may not help. It's just a direct question to Roger Penrose. Is consciousness in the brain? Well, it's a feature of the brain's activity, no doubt about that, but you want to locate it in a certain place. I'm just asking whether on your view it's true that consciousness is in the brain. Well, when you say in, I'm very confused by that. I mean, it's a phenomenon. You're easily confused. It's a phenomenon which is an activity of the brain, yes.

I mean, it wouldn't be there if the brain wasn't there. But you want me to locate it with spatial coordinates or something, is that the idea? Because it's not a local thing. I'm sure it's not localized. It would help me to understand your view if you directly answered that question because on one understanding of your view, consciousness does seem to be in the brain.

It's a matter of these microtubules, where a matter means, it more or less is these microtubules. And that seems to me... It isn't the microtubules. I don't mind it being located... That seems to be an extremely unlikely idea. I'm not saying it is the micro... I never said that.

I think you keep bringing it back to that, and they're not saying that. But the alternative view is a truism, which is just to the effect that consciousness, whatever it is, and you're now saying you don't know what it is, is somehow based in the brain. We all knew that.

It's been true for a century. Last word to Roger Penrose. I think we're going to have to learn a lot more about what the physical world is like. This is the trouble. I mean, I think you have a very archaic view of what the physical world is like. We've got to know more about that

before we can answer these questions. Well, that's true. Very much. Well, I enjoyed that. And thank you very much. Roger Penrose. Thank you very much, Ted Honorick. and thank you for listening.

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