The Conscious Mind

Interview Transcripts

David Chalmers

Interview 3/8/06 by John Rieger

Part One

David Chalmers, the subject of consciousness certainly seems to produce a lot of flying feathers. John Searle wrote recently that “all the most famous and influential theories are false.” The International Dictionary of Psychology, which you quote, says “nothing worth reading has ever been written about it.” And the philosopher Patricia Churchland lampoons what you call “the hard problem” as “The Hornswoggle Problem.” What accounts for all this learned invective?

Well, the problem of consciousness is the last frontier for philosophy and for science. It’s the thing that we don’t understand. It’s the thing, consciousness is the property of ourselves that is most central to our own existence, right? All of us are conscious. We experience the world out there sort of indirectly, but we experience our own minds directly. So, number 1, absolutely central to our own existence. We know it absolutely directly. Number 2, absolutely mysterious, and ill understood. Put those two things together you get something that people care a lot about, but don’t yet know a lot about, and that makes for a lot of argument and disagreement.

Maybe you could be a little more explicit. What is the problem of consciousness, and why is it so hard to get a handle on?

The central problem of consciousness is that of direct subjective experience of a first person inner life of the mind. I find it useful to distinguish what I call the easy problems of consciousness from the “hard problem” of consciousness. The easy problems are how do we explain how people walk and talk and verbally report. Why are they sometimes awake. Why are they sometimes asleep. That’s consciousness from the outside, the third person perspective on consciousness. The hard problem of consciousness is the first person perspective. While all that walking and talking and processing is going on, there’s something that it’s like from the inside, a direct, first person, subjective experience of the mind. The hard problem of consciousness is where on earth does that come from? How can we explain that first person experience of seeing, of hearing, of feeling in terms of the interactions of a whole lot of neurons in the brain? You know, why doesn’t it all go on in the dark? That’s the fundamental problem of consciousness, and right now nobody has a good answer to it.

You say that consciousness is a surprising feature of the universe? What’s so surprising about it?

Just think of the universe the way that some people like to think about it, as a bunch of atoms in the void. We’ve got this giant 4-dimensional creature stretching from the big bang to the big crunch, maybe infinite in all directions, and there are particles within it, fundamental particles making up atoms, making up molecules, making up cells, making up living beings. You look at all this from the objective, third person point of view and it makes sense to some extent—physics, it gives you chemistry, it gives you biology, and so on. But nothing in all of this looked at from the third person perspective makes it predictable that there would be such a thing as consciousness.

Now you might think if God designed a universe like that, atoms all the way up, it would be a universe of extremely fine-tuned machines—organisms, automata, you know, interacting in extremely complex ways. But there’d be no reason to expect that there’d be something that it’s like for these machines, from the inside, to experience the world. Where would feeling, or experience, or mind come into this picture? So we know we are conscious, it’s a fundamental fact of our existence, but we only know that from the inside, and if I just looked at you from the outside and saw the way that you were walking and talking and so on, I’d have no particular reason to believe that there’s a first person, subjective point of view.

Now wait a minute buddy!

Now I think you’re conscious; I don’t think you’re a zombie, but the reason I think you’re conscious is I’m conscious, and I think you’re like me. So the fundamental fact of consciousness comes from my own first person knowledge of the mind. You know, Descartes said, “I think, therefore I am.” I know I’m thinking, I know I’m conscious, so I know I’m here, and then derivatively I know you’re there too.

When you’re talking about consciousness, I’m just an ordinary guy, I go about my life and I spend most of my time focused on things like work and food. What’s consciousness in all that? Where is something you can point to and say “there’s an example”?

Ok, so you’re eating your meal, and let’s look at you from the outside point of view: okay, you look at your plate and you see a nice bit of hamburger there, and you pick it up and you put it into your mouth, you chew on it a bit, you swallow it, this sends some signals up to your brain, your brain processes it, and you react, and maybe you say “yumm.” That’s all from the third person point of view. That’s behavior, and that’s processing. But now we look at it from the first person point of view. When you ate that, it tasted like something to you. It had a really distinctive, subjective experience of, you know, the taste of hamburger. When you listen to music, there’s a bunch of processing from the outside—hits your ear, hits your brain, you react—that’s all behavior and processing. But consciousness is the direct, subjective experience of the music, what it sounds like to you in the inner movie theater of your mind, this movie theater we have made up of, you know, far more complex than any normal movie, made up of images and sounds and tastes and feelings, the stuff that we experience directly: that’s what I mean by consciousness.

Do you think that we have an intuitive sense of the philosophical questions here? Does our ordinary talk about consciousness and minds and brains make any sense?

Yeah, I think most people do have a pretty good idea of what we mean by consciousness. Consciousness is so straightforward that sometimes it’s hard to get people to see what the problem is. I mean, we know about consciousness really directly. The problem really comes about once you’ve got within a certain kind of scientific point of view—you know, the point of view of the physical universe, of the third person understandable viewpoint of science. Once you’ve got to there—and that’s already a step away from the ordinary common sense picture of the world—once you’ve stepped into the scientific picture of the world, the question then is how do you recover consciousness from that. So, you know, for some people that’s an extra step. They say, “well, what’s the problem of consciousness, it’s the most straightforward thing in the world?” The problem is how to reconcile this straightforward thing with this massive body of theory that we have in science.

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Part Two

Well, now I’ve been thinking lately about itches.

Itches?

Itches, yes. When I have an itch I have a disposition to scratch. But if I look a little bit more closely and ask what does the itch feel like, well, then I find I run into a puzzle, because I can say, well, it feels like somebody is poking me with a pencil, or it feels like a bug is crawling on my skin—all references to external objects, all references to possible causes of the sensation, but no intrinsic language for the description of the sensation itself. The sensation of an itch, like the redness of red or the sweetness of something sweet, seems to be strangely ineffable, and isn’t that rather suspicious? Isn’t it kind of strange that we can only characterize inward experiences be reference to outward circumstances?

Yeah! It’s one of the big problems of consciousness that makes it so challenging. Wittgenstein said something like, “an inward process stands in need of an outward criterion.” So it’s a problem about the relationship between consciousness and language. The words we have for describing consciousness all seem to be sort of relational. They depend on these external properties. Why? Well, that’s the way that language learning works. In learning a language and getting words for experiences, in getting words for things, we look at things that we can all point to together. So I can point to a certain bit of food, or I can point to a fly, I can point to a tree, and we’ll get words for those things. When it comes to getting words for consciousness, I can point to my inner state of consciousness, but that won’t help you, because you can’t see my state of consciousness directly. Instead we can see something like, you know, the mosquito and point to that and then talk about the sensation you get when the mosquito stings you, and say, “Okay, that’s an itch.” But it is interesting that we don’t have these pure sensation words for consciousness. I don’t think any of that suggest that these states aren’t real. I think they’re still perfectly real, but it’s a problem in the language we have for taking about them.

We’ve seen some radical moves in the direction of a materialism that eliminates all reference to inner states in the 20th century, and we still have philosophers active today who think that the discussion of inner states is more or less meaningless.

Well it’s interesting. Psychology got started as a science of consciousness, and the psychologists in the mid-nineteenth century thought the fundamental object of their study was states of consciousness, introspected directly, and they made some progress. But around the early 20th century some people started to get frustrated with this. People differed in the conclusions they came to. One person said they introspected one thing; another person introspected another thing. So there was a backlash, and this backlash led to the onset of behaviorism in the sciences of the mind for much of the 20th century. People said, okay, here’s a good objective way to study the mind. We’ll study things we can measure directly from the third person point of view. We’ll study behavior. And things gradually got better in the second half of the twentieth century, as people said, okay, we can look at inner processes too—the brain, the mechanisms, and so on.

But still until quite close to the end of the 20th century there was a fear of bringing consciousness and subjectivity back into science because of this thought that it’s so hard to access directly. Now I think things have got a lot better in the last ten or fifteen years. There’s been a real return to consciousness among scientists, but it’s still certainly true, there are people out there who think: science is what you can objectively measure; this stuff that you can’t directly measure objectively, it’s just, you know, that’s not science, that’s religion or spirituality or philosophy or something else.

Why do you think people have come back to taking consciousness more seriously?

I think everybody in their heart of hearts knew all along that this was the central challenge for a science of the mind. And, you know, consciousness is one of the major problems, maybe the major problem that science hasn’t yet figured out. At the end of the day, if we were to just ignore it and set it aside, we wouldn’t be respectable scientists. As scientists, as philosophers we need a whole picture of the world.

So what’s happened in the last 10 or 20 years is, I guess, that people have felt that, okay, now maybe we’ve got a way into the phenomena. Certain tools have been developed that have made it possible for people to approach what seemed like this huge mystery in a sort of step by step way. One of them is the development of imaging tools for looking at what’s going on in the brain, and also other tools for investigating what’s going on at the level of neurons to try and figure out the neural correlates of consciousness, those brain states that go along with states of consciousness. Of course that doesn’t remove the mystery, but it’s a way into the problem.

Suppose we had determined all the neural correlates of consciousness. In fact, suppose we understood the necessary and sufficient conditions for consciousness so completely that we could build a conscious something, a conscious machine. Would there still be something left to explain?

I think there might be. At least, it’s not guaranteed that doing all that is going to explain everything about consciousness. Now it could happen that in coming to understand the neural correlates of consciousness and getting a really good picture of all these mechanisms, then we’d have the insight, the crucial insight that would enable us to see, okay, well, here is the connection between all that and consciousness, but I think it would have to be an extra insight. Merely mapping out all the brain areas, and what’s active and what’s not, what leads to certain kinds of motor behavior, what leads to certain kinds of integration, what leads to a certain kinds of report—merely doing that won’t tell you why we’re conscious. I mean, in principle you can imagine all that going on in a robot, in a zombie, with no first person point of view at all. So neural correlates are absolutely central to the science of consciousness, but on their own they’re not enough. We need the extra thing that tells you why is it that when you have all that processing you then get these first person data of consciousness. That is, we need some part of the theory that’s the bridge between the neural story and the phenomenological first person story about consciousness.

Well, since you mention zombies, it’s always sort of amused me that only in the philosophy of mind and in horror movies do we dependably encounter zombies. Maybe you could introduce us to the zombie more intimately, and tell us what the zombie has to say about consciousness?

The zombies that philosophers talk about are different from the ones you see in Hollywood movies, or the ones you hear about in the Haitian tradition of voodoo. I guess the ones you see in Hollywood movies are creatures risen from the dead that like to go around eating people’s brains. The ones you see in the voodoo tradition are creatures that have had a curious sapping of free will, and act like slaves to their masters. Philosophical zombies are not quite like that. They’re behaviorally identical to ordinary human beings. From the outside they walk, they talk, they respond just like a normal person. But on the inside they’re not conscious. Now nobody thinks zombies exist. They’re a purely hypothetical construct, a thought experiment. But people talk about them because they provide a contrast with us, the conscious beings that we know we are.

The question is, why aren’t we zombies? Why couldn’t evolution just have produced a bunch of creatures who walk and talk and respond as sophisticatedly as you and as me, but without any first person subjective experience of colors, of sounds, of tastes, of images, of feelings? Now it didn’t, but why didn’t it? Why couldn’t there have been a universe that was particle for particle identical to ours, but in which there was no consciousness—it was just a world of zombies? Our world is not like that, but I don’t see any contradiction in that hypothesis, so the thought is, well, what was the extra thing that had to happen to get consciousness into our world instead of it being a world of zombies? And that’s a way of getting at the philosophical problem of consciousness.

Can a thought experiment like that really get any purchase on the world? How can you prove anything about the world with a thought experiment like that, to wit, that something extra would be required to explain consciousness?

Here’s one way to think about it. What we get from scientific and experimental investigations of consciousness is facts about correlations between brain states and consciousness. You know, this neural state, this kind of consciousness. This kind of behavior goes along with this kind of consciousness. But correlations aren’t enough—you know, when one thing happens, the other thing happens. What we want out of a theory of consciousness is explanation, and explanation requires something stronger than correlation. And here is where, I think, reasoning is required to distinguish between correlation and explanation. If it turns out, for example, that it’s perfectly coherent to imagine all those brain processes going on in the absence of consciousness, then it looks like our theory needs an extra component to explain why it is that when you have all those brain states you get consciousness.

So here’s what I take to be the moral of the big mystery of consciousness: the fact that you can’t get it all from the third person point of view means that the fundamental principles of physics, although they might be enough to get you to chemistry and to biology and so on, they’re not enough to get you to consciousness. What does that mean? You’ve just got to add in something extra and fundamental into our theory. And we’ve done that before. Fundamental theories of nature get expanded. My view is that to bring consciousness into the picture, our fundamental theory of nature needs to be enlarged.

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Part Three

Well now you’ve actually suggested that we might need a new class of fundamental properties—phenomenal or I think you’ve called the “proto-phenomenal” properties—sort of consciousness precursors, if I get you right. How does that get us anywhere?

Well we have this phenomenon that, you know, this has come up a number of times in the history of science. Say, you know, Maxwell trying to explain electromagnetic phenomena in terms of the fundamental entities they had already—space, time, mass and so on. It turns out it couldn’t be done. To explain electromagnetic phenomena you needed to go beyond space, time and mass and so on. You needed to introduce the new fundamental property of electric charge, and new fundamental principles of electromagnetism that helped us bring in electromagnetic phenomena. I mean, I think that what we’re confronting now in the case of consciousness is something analogous to this: we’ve got our fundamental entities—space, time, mass, charge, and the fundamental laws governing that. Well that gets us a lot of stuff. None of it tells us why there should be consciousness, or tells us what consciousness should be like.

So I think the moral here has to be the same. Every now and then our repertoire of fundamental properties has to be expanded. Let’s bring in some new ones—consciousness or proto-consciousness or whatever—then once we’ve done that we can look at the fundamental laws and connect consciousness to the underlying physical properties and the pre-existing properties. Once we’ve done this we have so much more power in our theories, we can start articulating this fundamental connection between the third person domain and the first person domain, and then we can start saying, okay, what is the right connecting principle, where the theory that lacked those things just left consciousness out entirely.

So in an age when the dominant scientific paradigm is overwhelmingly physicalist, you seem to be some kind of a dualist, with the additional twist that you’ve got a kind of an atomist dualism. Maybe there are consciousness atoms? Maybe the nature of conscious things is determined by the nature of its fundamental particles, just the way since the dawn of modern physics we’ve taken the nature of physical things to be determined by the nature of their fundamental particles. Am I following you here?

Yeah… I think of myself as a naturalist, somebody who wants to explain everything, including very complicated things, in terms of very simple things. And I take it this is what we’ve got out of the progress of science: we’ve managed to boil down the complex to explanations in terms of simple properties interacting by simple laws. And I’d like to think the same goes for consciousness. But the moral is even though physicalism is an extremely attractive point of view—it’s one that I’ve been very attracted to myself—everything we’ve learned about consciousness tells us that just taking the kind of fundamentals that physics gives you and the kind of fundamental laws that they give you, nothing there is ever going to bring consciousness into the picture. So we’ve got to add something else to the picture, and, you know, by extending naturalist reasoning, I think the default hypothesis should be that what you add is as simple as possible. Extra simple fundamental laws, extra simple fundamental properties. And then see where that will get you.

Well, now you do spend some time on this in The Conscious Mind, so I don’t feel I’m trying to draw you into saying things that you haven’t said before, but I certainly think you’ve said some things… I know that, in his review of your book in the New York Review of Books eight or nine years ago, John Searle must have set a record for using the word “absurd” in a short article in addressing some of these views of yours, and in particular the idea that these phenomenal or proto-phenomenal properties could exist, and what would they be, would it be that some form of rudimentary inwardness associated with atoms and molecules? Would tiny little particles have tiny little mental attributes? These are very strange speculations that you’ve engaged in.

Well, I think one thing we’ve learned from the progress of science over the last hundred years or more, is that the universe is a pretty strange place. We shouldn’t expect the universe to conform to our first intuitions of common sense. We’ve found that already with quantum mechanics, with relativity, and perhaps string theory. And so I don’t place too much weight on common sense intuitions of here is how one would expect the world to be.

But here the question is how far down the natural order does consciousness go? I take it that we think that humans are conscious. Most of us think that monkeys and dogs and cats are conscious. You start to ask people about worms and flies, whatever, and, yeah, maybe they have some simple experience. And then the question is, as systems get smaller and simpler and so on, where does consciousness disappear, where does it wink out? And here I think the fact is we just don’t know the answer to that question. And there are two possibilities. One is that it winks out somewhere around the level of the cell or the fly or the worm. The other possibility is that it goes all the way down.

Now maybe you think that sounds strange and mysterious, but, damn, we already know that subatomic physics is as mysterious and strange as it could be. We don’t have the consciousness meter to measure physical systems from the outside, so one speculation—one that a lot of scientists and philosophers have taken seriously throughout history—is maybe there’s some precursor to consciousness at the bottom of the natural order. I mean, many people have pointed out that physics characterizes its entities only extrinsically. You know, we hear about atoms and electrons in terms of how they affect other atoms and electrons. It doesn’t tell us what they’re like in themselves. You know, Immanuel Kant said we can never know the nature of the thing in itself. So one speculation that I think is worth taking seriously is the idea that right down there at the bottom of the natural order is some basic precursor to consciousness.

Now it’s just speculation. I don’t know whether that’s true. But if it is true, then it really would allow an integration of consciousness with physics in a very fundamental way, and merely saying it seems counterintuitive to me that an atom should be associated with some precursor of consciousness, I just don’t think that carries terribly much weight. The question is whether that hypothesis can, at the end of the day, end up playing a powerful theoretical role for us in giving an explanation of consciousness, and that’s just an open question.

You’ve also entertained—and here again I won’t say you’ve espoused, but you’ve entertained the idea that there might be something that it’s like to be a thermostat. Do you think a simple mechanism like a thermostat could be conscious in some sense, and why even pursue that speculation?

Well, it seems kind of strange and bizarre to think a thermostat could be conscious, but it seems strange and bizarre from the outside to think, if you didn’t know already, to think that a brain could be conscious—this big gray mass of stuff with complex interacting electrical signals. But we know the brain is. So now the question again is, how much simpler can you get and still have consciousness? Well, you go down to the earthworm, you go down to the bacteria, and the question is, okay, at what point down the way do we lose the thing which is essential to consciousness?

Now there are two kinds of hypotheses. One is that consciousness requires a special kind of complexity. Maybe it takes you a thousand pieces interacting in just the right way to give you consciousness. That’s just an hypothesis. No one’s ever given any evidence for it. It could be true. But the other hypothesis is that consciousness comes from actually something very simple. So one idea that I’ve got some sympathy with is that consciousness arises from information processing itself. Anything which processes any kind of information is gonna be associated with some kind of consciousness. Much simpler consciousness than the kind we have.

Nobody is suggesting that a thermostat is going to be able to think, or have emotions or dream, and so on, but the thought is, okay, a thermostat is the simplest possible information processing mechanism. It’s got three different states, which we think of as too cold, too hot, just right. Who’s to say that associated with that extrinsic characterization of the states of something like a thermostat there isn’t some primitive precursor state of consciousness that’s somehow analogous to what goes on in the brain, but at the simplest possible level. Maybe it sounds crazy, but I don’t think one ought to place too much weight on common sense here. It’s a matter of where our best theories go.

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Part Four

I want to go in another direction here. I’ll take another example that John Searle’s fond of. A restaurant offers me a choice of pasta or veal. I reflect a bit, I make up my mind and I order the veal. So I made a conscious choice which resulted in the action of ordering the veal. So, consciousness can be a cause of physical events. Now, is there anything problematic about that story?

Right now we don’t know. Again, the very natural intuitive reaction is, sure, whenever I’m conscious this makes a direct difference to my behavior. I feel the flame, it hurts, I withdraw my hand. But there’s two different views here. One is that consciousness makes a difference. The other one is that it doesn’t. David Hume observed that whenever we see two things happening right next to each other in regularity—you know, a conscious choice, and then a physical action—we infer a causal connection there, because we experience them together. But we don’t know that.

One of the big questions that’s central in this field is how does consciousness actually make a difference inside the natural order, and right now nobody has a really good answer to that question, so there’s a number of different hypotheses. But one of them, which I take very seriously, is that it doesn’t, and that consciousness is sort of, you know, the first person, if you like, projection of all of that third person activity, but it doesn’t reach back in and make a difference. Another hypothesis is that it does, and right now I think we’re not at the point where we can choose between those.

Well, that first option that you mentioned is often called epiphenomenalism. Are you an epiphenomenalist?

I don’t know. What leads many people to take epiphenomenalism seriously—it’s a combination of two things. One is that consciousness is something that goes beyond the physical. You’re not going to be able to get a complete explanation of consciousness in physical terms. Two is the idea that physics, the physical, is a closed system: for everything physical that happens at the bottom level of physics or even in the brain, there’s a physical cause and a physical explanation. Put those two things together—everything physical has a physical cause, but consciousness isn’t physical—then it becomes very hard to see how consciousness can itself make a difference to physical events, because that would require something physical having a non-physical cause. So that’s the reasoning that leads some people to epiphenomenalism. Denying it then requires denying one of the two principles that got you there—either saying that consciousness was physical all along, or saying that physics isn’t causally closed in that way.

Is there a similar problem going the other direction, how the physical effects consciousness?

Yes and no. The disanalogy… I mean there’s a big question how could something physical affect something in consciousness. But the disanalogy is, in physics we have this principle of closure. Everything physical has a physical explanation. It’s a beautiful, closed, autonomous system. Consciousness doesn’t seem to be like that. Events pop into consciousness out of nowhere all the time with no particular conscious cause, consciousness fades away and so on, so if you just look at the consciousness in the world, it doesn’t seem to form this closed, autonomous system. So there’s not a problem which is analogous to the one that came up with physics—how could something interfere with that? In fact. you look at states of consciousness, so jumbled and chaotic, it looks like they’re just crying out for external causes. There are physical processes that affect consciousness, there are unconscious processes that affect consciousness, and so on, so there’s much less of a problem with the idea that the kind of regularities that you find in consciousness could be the product of regularities in an underlying physical order. Although, of course, there’s still an explanation about what form would that connection take.

It’s true that all these studies of split brain patients, and brain-damaged patients, and neural correlates of sensory awareness and that kind of thing have shown in great detail that, do something to the brain and your states of awareness change. But on the other hand I think all of us are deeply committed to the idea that we don’t just “wait and see” what we choose. We decide, and we choose the veal.

Oh sure, we decide, we choose the veal, but that leaves open the role of consciousness in that choice. I mean, each of us are complexes, I think, of conscious aspects and unconscious aspects and physical aspects. We are not merely our consciousness. We are not merely our brain. We’re big complexes of both. So it’s an open question what goes on when we decide and when we choose.

So here’s one view: first you get the state of consciousness, you know, the conscious decision, and that bit of consciousness reaches back in and affects the choice. But here’s another view: I’m a big complex of physical stuff, unconscious stuff and conscious stuff. All that goes on when I make a choice. There’s a bunch of physical stuff happening, there’s a bunch of conscious stuff happening, and it’s the physical stuff that makes my arm reach out and do what it does, and the conscious stuff is a kind of projection of that. Now does that imply that I didn’t make a choice or that I didn’t have free will?

Well, “conscious” choice—nothing seems more characteristic of it than that element of free will?

Yep, but it is an open question what the relationship is between the conscious experience of choice and the event that happens. And, you know, plenty of psychologists have done studies in recent years suggesting that, you know, the conscious experience plays a less central role in that choice than we thought that it did. There are cases, for example when people think they’re doing the choosing when in fact something else is doing the choosing. There are cases where people have the experience of making a conscious choice, but things have happened in their brain a half a second beforehand that already make it look like the choice has been determined.

Now I’m not saying those prove anything, but I’m saying it’s an open question just what the relationship is between that conscious experience of choice and the later action. And I’m not sure that it’s such a great catastrophe if it turns out, that consciousness turns out to be a projection of a bunch of underlying mechanisms in the brain. I think that consciousness is the thing that gives meaning to our lives. It gives an interpretation to all that sort of meaningless stuff that’s going on underneath in the brain, in the world and so on. Is it central to all that, that consciousness needs to feed back in and affect that stuff? Well, it would be intuitive and nice if it did, but it doesn’t seem to me to be obviously essential.

Searle, whom I’ve mentioned a couple of times here, says quite adamantly that consciousness is a physical phenomenon, like digestion, caused by the brain, which just happens to have a first person ontology. It’s a physical phenomenon that just happens to have a first person ontology. Does that solve any problems as far as you can see?

Well, I think it’s not clear that this view is entirely consistent. One is, if you’re saying it’s a physical process in the brain, you’re saying it’s reducible to a physical process in the brain, and at the same time you’re saying it has its own irreducible first person ontology, then those two claims, I think, are in strong tension with each other. Now digestion is reducible to a process in the stomach. We wouldn’t even normally say that digestion is “caused by” processes in the stomach. Digestion just is those process in the stomach. So now the question is, okay, we could be reductionists about consciousness, and say consciousness just is that process in the brain, or we can say consciousness is caused by those processes in the brain, but once you say consciousness is caused by those process in the brain, as Searle did there, you’re implying that it’s in a certain sense separate from and irreducible to those processes in the brain. And then you start saying consciousness has its own first-person ontology, and you’re starting to say, okay, consciousness isn’t so analogous to those purely reducible physical processes like digestion after all. And I suspect that’s the position where that reasoning of Searle will end up taking one if you pursue it to the end, although maybe Searle himself doesn’t want to go that way.

Well, somebody once said that the history of philosophy is characterized not so much by solving problems as by losing interest in them. Do you think that we will have a theory of consciousness, of phenomenal consciousness, of first-person experience, or do you think we’ll just throw up our hands, and move on, and be satisfied with cognitive neuroscience?

I don’t think the problem of consciousness is ever going to go away. I mean it’s had its ups and downs in the history of the subject, but it’s one of the central problems, not just of philosophy, but of science. It’s a manifest datum of our existence that we’re conscious. And it’s just manifest that it poses a special problem of explanation. So there may be a few cycles to come where people throw up their hands, but people are always going to come back to it, and I don’t think it’s the case that we’re ever going to be satisfied just with a story about the mechanisms and about the behavior that leaves consciousness out. So it’s going to keep coming back and hitting us in the head. And I’m an optimist about these things. I don’t think the solution is around the corner. We’re not talking ten or twenty years. But fifty years, a hundred years down the line, things are gonna look pretty different. We may have a different conception of what the ingredients are gonna be for a theory of consciousness, and what its shape might be. And I’m optimistic that 100 years, maybe 200 years down the line we’re going to be a whole lot closer at least to a theory of consciousness than we are now.

Professor Chalmers, thank you very much.

Thanks a lot.

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