John Searle on Consciousness and the Brain at TEDxCERN (Transcript)

I don’t think: “Well, maybe these guys are right.” 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. That’s the first feature of consciousness. It is real and irreducible. You cannot get rid of it by showing that it’s an illusion, in a way that you can with other standard illusions.

The second feature is this one that has been such a source of trouble to us. And that is all of our conscious states have this qualitative character to them; there is something that it feels like to drink beer, which is not what feels like to do your income tax, or listen to music.

And this qualitative field automatically generates a third feature, namely, conscious states are by definition subjective, in the sense that they only exist as experienced by some human or animal subjects, some self that experiences them. Maybe we will be able to build a conscious machine. Since we don’t know how our brains do it, we are not in the position so far to build a conscious machine.

Okay, another feature of consciousness is that it comes in unified conscious fields. So I don’t just have the sight of people in front of me, and the sound of my voice, and the weight of my shoes against the floor, but they occur to me as part of one single great conscious field that stretches forward and backward. That is the key to understanding the enormous power of consciousness. And we have not been able to do that in a robot. The disappointment of robotics derives from the fact that we don’t know how to make a conscious robot, so we don’t have a machine that can do this kind of thing.

The next feature of consciousness after this marvelous, unified conscious field is that it functions causally in our behavior. I gave you a scientific demonstration by raising my hand, but how is that possible? How can it be that this thought in my brain can move material objects? Well, I will tell you the answer. I mean we don’t know the detailed answer, but we know the basic part of the answer — and that is, there are sequences of neuron firings and they terminate where the acetylcholine is secreted at the axon end-plates of the motor neurons, sorry to use philosophical terminology here. But when it is secreted at the axon end-plates of the motor neurons, a whole lot of wonderful things happen in the ion channels and the damned arm goes up.

Now think of what I have told you. One and the same event, my conscious decision to raise my arm has a level of description where it has all of these touchy-feely, spiritual qualities, it’s a thought in my brain but at the same time, it’s busy secreting acetylcholine and doing all sorts of other things as it makes its way from the motor cortex down through the nerves fibers and the arm.

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Now, what that tells us is that our traditional vocabularies for discussing these issues, are totally obsolete. One and the same event, has a level of description where it’s neurobiological, and another level of description where it’s mental, and that’s a single event and that’s how nature works, that’s how it’s possible for consciousness to function causally.

Now, with that in mind, with going through these various features of consciousness, let’s go back and answer some of those early objections.

Well, the first one I said, was consciousness doesn’t exist, it’s an illusion. Well, I’ve already answered that, I don’t think we need to worry about that.

But the second one, had an incredible influence and may still be around, and that is if consciousness exists, it’s really something else; it’s really a digital computer program running in your brain, and that’s what we need to do to create consciousness, is get the right program. Forget about the hardware, any hardware will do, provided it’s rich enough and stable enough to carry the program.

Now, we know that that’s wrong. I mean, anybody who’s thought about computers at all can see that that’s wrong. Because computation is defined as symbol manipulation, usually thought of as 0s and 1s, but any symbols will do. You get an algorithm that you can program in a binary code and that’s the defining trait of the computer program. But we know that’s purely syntactical, that’s symbolic, we know that actual human consciousness has something more than that, it’s got a content, in addition to the syntax, it’s got a semantics.

Now, I made that argument, — oh, my god, I don’t want to think about it — more than 30 years ago, but there is a deeper argument implicit in what I’ve told you. And I want to tell you that argument briefly, and that is: consciousness creates an observer independent reality. It creates a reality of money, property, government, marriage, CERN, conferences, cocktail parties, and summer vacations. And all of those are creations of consciousness. Their existence is observer-relative. It’s only relative to conscious agents; that a piece of paper is a money, or a bunch of buildings is a university.

Now, ask yourselves about computation. Is that absolute? Like force, and mass, and gravitational attraction? Or is it observer-relative? Well, some computations are intrinsic. I add two plus two to get four, that’s going on no matter what anybody thinks. But when I hold out my pocket calculator and do the calculation, the only intrinsic phenomenon is the electronic circuit and its behavior. That’s the only absolute phenomenon. All the rest is interpreted by us.

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Computation only exists relative to consciousness. Either a conscious agent is carrying out the computation or it has got a piece of machinery that admits of a computational interpretation. Now that doesn’t mean computation is arbitrary, I spent a lot of money on this hardware, but we have this persistent confusion between objectivity and subjectivity as features of reality, and objectivity and subjectivity as features of claims.

And the bottom line of this part of my talk, is this: you can have a completely objective science, a science where you make objectively true claims about a domain whose existence is subjective, whose existence is in the human brain, consisting of subjective states or sensations, or feeling, or awareness. So the objection, that you can’t have an objective science of consciousness because it’s subjective, and science is objective, that’s a pun, that’s a bad pun on objectivity and subjectivity. You can make objective claims about a domain that is subjective in its mode of existence, and indeed, that’s what neurologists do. You have patients that actually suffered pains and you are trying to get an objective science of that.

OK, I promised to refute all these guys, but I don’t have an awful lot of time left, but let me refute a couple more of them.

I said that behaviorism ought to be one of the great embarrassments of our intellectual culture, because it’s refuted the moment you think about it. Your mental states are identical with your behavior? Well, think about the distinction between feeling a pain, and engaging in pain behavior. I mean, I won’t demonstrate pain behavior but I can tell you I am not having any pains right now. So it’s an obvious mistake.

Why did they make the mistake? The mistake was, and you go back and ready the literature on this, you can see this over and over, they think, if you accept the irreducible existence of consciousness, you’re giving up on science, you’re giving up on 300 years of human progress and human hope and all the rest of it.

And the message I want to leave you with is consciousness has to become accepted as a genuine biological phenomenon, as much subject to scientific analysis as any other phenomena in biology, or, for that matter, the rest of science.

Thank you very much.