Anil Seth: How Does Your Brain Construct Your Conscious Reality? When we look around, it feels like we're seeing an objective reality. But neuroscientist Anil Seth says everything we perceive, from objects to emotions, is an act of informed guesswork by the brain.
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How Does Your Brain Construct Your Conscious Reality?

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How Does Your Brain Construct Your Conscious Reality?

How Does Your Brain Construct Your Conscious Reality?

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GUY RAZ, HOST:

Today on the show, ideas about What Makes Us Us. And on that and most other questions, philosopher John Searle...

JOHN SEARLE: Hello.

RAZ: ...Is a pretty straight shooter.

SEARLE: Now try to speak a bit louder if you can.

RAZ: Sure. You can hear me OK?

SEARLE: Now you can. Yeah.

RAZ: OK. I was far away from the microphone. How are you?

SEARLE: Well, I'm OK, a bit - well, let's say hung-over. How about that?

RAZ: You're hung-over? What were you drinking?

SEARLE: Well, we had a pretty good dinner last night. And also I'm still - that's on top of jetlag. I got back from Europe a few days ago. But other than that, almost awake. How about that?

RAZ: (Laughter) That's great. But are you - but are you conscious?

SEARLE: Well, the truth of the matter is I am the decisive authority on that. And the answer is yes.

RAZ: (Laughter) OK, good.

John Searle's been teaching philosophy at UC Berkeley since...

SEARLE: '59, right.

RAZ: ...More than 50 years.

SEARLE: Seems like yesterday. But anyway...

RAZ: John's one of the leading experts on consciousness.

I've heard it described as sort of, like, the movie that we always have playing in our head. That's what consciousness is.

SEARLE: Well, OK. I don't like the movie metaphor because that suggests that there is a distinction between the movie and the guy watching the movie, and that's not true. We are the movie. It is the ongoing flow of conscious experiences that constitutes the magnificent feature of human life.

RAZ: But so little is known about consciousness, about why being you feels like something. And that's partly because consciousness and where it comes from is a relatively new question. At least...

SEARLE: That's right.

RAZ: ...In science.

SEARLE: When I first got interested, I used to go and talk to the brain-stabbers, you know, these neurobiologists and tell them look, what the hell am I paying you guys to do? Get busy, and solve the problem of consciousness. And a standard answer I got was, not a suitable subject for science. Science is about objective phenomena.

RAZ: Yeah. Like, well - this is for - this isn't real science.

SEARLE: Too kooky.

RAZ: Yeah, kooky.

SEARLE: And that's a mistake to think that. And now that has changed. We're now at a stage where consciousness - a perfectly respectable scientific problem like any other.

RAZ: So here's one of the biggest questions about consciousness, whether it's simply a product of the human brain or whether it's something more, whether our conscious mind lives on after we die, whether it was somewhere else before we came to be. Now, John Searle definitely comes down on one side of the question.

SEARLE: Consciousness is a biological process like, digestion or photosynthesis or the secretion of bile. And what we need to do is figure out how the brain does it as a biological piece of machinery.

RAZ: John explains exactly what he means on the TED stage.

(SOUNDBITE OF TED TALK)

SEARLE: Why consciousness? Well, it is the most important aspect of our lives for a very simple logical reason. Namely, it's a necessary condition on anything being important in our lives that we're conscious. I've - haven't yet given you a definition. You can't do this if you don't give a definition. People always say consciousness is very hard to define. I think it's rather easy to define, if you're not trying to give a scientific definition. We're not ready for a scientific definition. But here's a common sense definition.

Consciousness consists of all those states of feeling or sentience or awareness. It begins in the morning when you wake up from a dream of asleep. And it goes on all day until you fall asleep or die or otherwise become unconscious. Dreams are a form of consciousness on this definition. Now, that's the common sense definition. That's our target. If you're not talking about that, you're not talking about consciousness. OK. Now, why, then, is this curious reluctance and curious hostility to consciousness? Well, I think it's a combination of two features of our intellectual culture. But in fact, they share a common set of assumptions.

One feature is the tradition of religious dualism. Consciousness is not a part of the physical world. It's a part of the spiritual world. It belongs to the soul. And the soul is not a part of the physical world. That's the tradition of God, the soul and immortality. There's another tradition that thinks it's opposed to this but accepts the worst assumption. That tradition thinks that we are heavy-duty, scientific materialists. Consciousness is not a part of the physical world. Either it doesn't exist at all, or it's something else - a computer program or some damfool thing.

But in any case, it's not part of science. And I used to get into an argument that really gave me a stomachache. Here's how it went. Science is objective. Consciousness is subjective. Therefore, there cannot be a science of consciousness. OK. So that's - these twin traditions are paralyzing us. It's very hard to get out of these twin traditions. And I have only one real message in this lecture. And that is all of our conscious states, without exception, are caused by lower-level neural biological processes in the brain. And they are realized, in the brain, as higher-level or system features.

RAZ: So how does consciousness originate in our biology?

SEARLE: Well, we don't know the details of how the brain produces consciousness, but we know it does. And that's the stunning thing about our life. Each of us is conscious. And we have that peculiar form of consciousness, which is human consciousness. And the way that it's possible is because of the neuronal configuration of the brain.

However, for me to say it that way is really just a blank check. We don't know the details of how it works. And I think it's kind of one of those scandals of intellectual life is we do not know how brain processes cause and sustain consciousness. But we know they do. And that's the important fact for this discussion right now is we are conscious beasts. Consciousness is produced in the brain, and it's maintained in the brain.

RAZ: It is amazing. There you are in Berkeley. I'm in Washington, D.C. Here we are having a conversation. And it - as I speak, something is making me do this. Something is making me say these words and...

SEARLE: Yeah.

RAZ: ...Think about this in a specific way. And that is just mind-boggling.

SEARLE: Yeah. Well, OK. Here's the wonderful thing that you put your finger on right now. And that is this combination that we share, this enormous, shared background with other human beings. And yet, at the same time, each of us is absolutely unique.

RAZ: Yeah.

SEARLE: So it's this marvelous combination that I am part of a great river of humanity that stretches back - well, not merely thousands, but millions of years and that, on top of that, I have my own individuality. I can express my own uniqueness.

RAZ: But do we have any idea what causes it? Like, what gives us consciousness?

SEARLE: OK. A Darwinian natural selection has produced this enormous specialization among primates. And somehow or other, we lucked out. I mean, I think other primates are marvelous, but I have no desire to be a chimpanzee or an orangutang because I think we've got it made in the sense that we have this remarkable feature of human consciousness. So evolution has given us this fantastic property. But I - of course, evolution only works if there is a underlying substratum. We have the Atomic Theory of Matter. It eventually generates big carbon-based molecules.

At some point, some of those became alive and out of life grew human animal existence and finally human consciousness. And consciousness is an ordinary part of the physical world, and it's this tradition of thinking that the world divides into two kinds, the mental and the physical, and the mental is not studiable the way the physical is. That's a silly review, and I think we've overcome it. And now we've got to get busy and solve the problem of consciousness.

(SOUNDBITE OF TED TALK)

SEARLE: All right. But now we get into some harder questions. Let's specify the exact features of consciousness. Well, the first feature is it's real and irreducible. You can't get rid of it. You see, the distinction between reality and illusion is a distinction between how things consciously seem to us and how they really are. It consciously seems like there's a - I like the French arc en ciel. It seems like there's an arch in the sky. Or it seems like the sun is setting over the mountains. It consciously seems to us, but that's not really happening. But for that distinction between how things consciously seem and how they really are, you can't make that distinction for the very existence of consciousness because where the very existence of consciousness is concerned, if it consciously seems to you that you are conscious, you are conscious.

(LAUGHTER)

SEARLE: I mean, if a bunch of experts come to me and say we are heavy duty neurobiologists and we've done a study of you, Searle, and we're convinced you are not conscious. You are a very cleverly constructed robot. I don't think, well, maybe these guys are right, you know? I don't think that for a moment because - I mean, Descartes may have made a lot of mistakes, but he was right about this. You cannot doubt the existence of your own consciousness.

(SOUNDBITE OF MUSIC)

RAZ: OK. So we still cannot explain consciousness from a scientific perspective.

SEARLE: Yeah.

RAZ: But my question to you is if we could figure this out, right, in the same way, like, we pulled together and figured out the human genome.

SEARLE: Yeah.

RAZ: If we could figure out consciousness, could we recreate it? I mean, we could - we could we create artificial versions of ourselves, like conscious versions?

SEARLE: I don't see why not. Now, I don't think we're anywhere near this. And there may be theoretical obstacles that make it impossible. But as far as we know, the brain is an organ like any other. And if you understand how it works, then you can do it artificially in the same way that you can do an artificial heart. But if you think biologically, and I'm urging that we should think biologically, then it seems to me there's no obstacle in principle to two achievements. One is we have a complete understanding of how the brain does it. We're a long way from that, but I think it's a reasonable research project. And secondly, we have at least the possibility of doing it artificially.

RAZ: I mean (laughter) I mean, it seems that there is no attribute of being human that tells us more about a human, an individual human, than a consciousness.

SEARLE: Well, OK, but we are not the only beasts that are conscious. We know that the primates are conscious. I'm pretty certain all the mammals are conscious. So it isn't just us, but we have special forms of consciousness, special forms of society, special forms of culture, that other animals don't have. And all of those are expressed in our consciousness.

RAZ: I mean, our ability to be introspective, our ability to have this conversation.

SEARLE: Absolutely. Take away consciousness and NPR's out of business...

RAZ: Out of business.

SEARLE: ...As is the University of California.

RAZ: Yeah.

SEARLE: So the idea that some or other consciousness can be ignored or it doesn't matter - consciousness matters more than anything simply because if something is important, something matters only relative to consciousness. So people ask me sometimes, well, what's the function of consciousness? Why does it matter? And that's a crazy question. It's like saying, what's the function of life or why does life matter? Because everything else matters in relation to consciousness.

RAZ: Could there just be some mystery about it? I mean, could the consciousness process be something that really can't be figured out?

SEARLE: Well, that's always possible. We make this assumption - and we have to make it - that everything's understandable by us. Now, we know that that must be false for a very simple reason. Our brains are selected for hunter-gatherer environments. And as far as we know, there hasn't been any substantial change in the genome for 30,000 years or so. But we have every reason to suppose that there are limits to our brain's capacity to understand reality. We don't know in advance what the limits are, so we have to keep pushing forward as if there were no limits. And then we'll discover what the limits might be.

(SOUNDBITE OF MUSIC)

RAZ: John Searle is a professor of philosophy at UC, Berkeley. You can see his entire talk at ted.com.

(SOUNDBITE OF SONG, "JELLYFISH GENES")

SPRITES: (Singing) Why sell yourself short when you can be everything that you want? I'd like the mind of the brilliant man, please. I'll take the wings of a hummingbird. They say DNA make us who we are. Give me jellyfish genes so I can glow in the dark.

RAZ: Hey, thanks for listening to our show this week, What Makes Us Us. If you want to find out more about who was on it, go to ted.npr.org. To see hundreds more TED Talks, check out ted.com and the TED app. Our production staff here at NPR includes Jeff Rogers, Brent Baughman, Meghan Keane, Neva Grant, Sanaz Meshkinpour and Casey Herman, with help from Daniel Shukin. Our intern is Rachel Faulkner. Our partners at TED are Chris Anderson, Kelly Stoetzel and Janet Lee. I'm Guy Raz and you've been listening to ideas worth spreading right here on the TED RADIO HOUR from NPR.

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