Roger, what is it about consciousness that attracted you as a mathematical physicist to go into an area that you hadn't been in before? Well, I think my interest in this area came way before that. My father had a big interest in these issues, and he became interested, professionally, he was interested in the inheritance of mental disease.
But we used to have discussions about whether consciousness could be computational activity. It was the kind of thing that people were getting interested in. In fact, secretly, at one stage of my life, I was secretly wanting to be a brain surgeon, so I'd open the brains up and see how it worked, which never quite worked out.
But it was really later, when, still thinking that maybe we were all computers or something, I had an interest in Gödel's theorem. This was when I was an undergraduate in mathematics in London, London University. And I went to Cambridge then as a graduate student and there I went to courses on various things which I found interesting, like Bondi's course on cosmology and Dirac's course on quantum mechanics.
And another course which was given by a lecturer by the name of Steen, who talked about Godel's theorem and Turing machines and all this. And I think it was at that stage that I formed my view that there has to be something going on when we understand things, particularly mathematics, which is the... ...what it was about, which cannot be done by computers.
The understanding of what you're doing is something different from computation. I had no idea what it might be, but from Dirac's lectures I sort of picked up this paradox between the measurement process and the rules of quantum mechanics. What was the core element of consciousness that made you reject the computational theory?
I think it was the Gödel argument. And from Steen's lectures, it made it completely clear, and things he put it in a way which is not the way often people do it. People usually, at least in popular accounts, say, oh, well, Gödel's theorem shows there are things in mathematics you can't prove, you see, unprovable statements. And I didn't like the idea of that. But Steen made it completely clear that, well, provable by what means, you see.
Now, do you trust the means of proof? If you trust the means of proof, then you can transcend them. Now what's going on there, you see? It means our understanding enables us to go beyond any rules of proof that you trust. So I think I formulated my ideas then that what we do when we consciously understand something is not computation.
But that was really a result of the lectures in mathematical logic I went to in Cambridge. So that's the fundamental point, that... That consciousness is not computational.
So then you have to give another explanation. I think there's where Dirac's lectures came in. I felt you needed somewhere where there was a gap in our understanding. Now, I don't know how long it took me to formulate this belief.
I think it gradually came over many years. And I didn't think much of it. I just formed a view that what's involved in conscious thinking... Can't be entirely described by the physics that we know. And where is the main gap in the physics we know?
Well, it's in the quantum mechanical, the sort of contradiction between the continuous evolution that's given by the Schrodinger equation and the discrete probabilistic thing which happens when you make a measurement. The two things fit nicely together, but they're inconsistent with each other. And the... the argument against that is that you have two mysteries and you try to solve two mysteries like a simultaneous equation and magic it works. Well I know people accuse me, well one mystery, one mystery, why don't they fit?
It's not that you see. No, it's clearly logical. Whether it's taking logic too far, I don't know.
It's that there has to be something outside the physical, it has to be something which is important to something of the physical. the operation of the bit. There are lots of things we don't know, you know, we don't know even now whether the universe is spatially open or closed. Well, what's that got to do with it?
We don't know what rules are that define the masses of particles individually. There's lots of mysteries there. That's not directly relevant. But something, the only thing which could be directly relevant is this big gap in our understanding which has to do with the two procedures of quantum mechanics which are inconsistent with each other. So it needs some other theory to fill that gap.
And that is the one place that I could think of, and still the only place I can think of, You've got a big enough gap which could be filled by some new theory in which computation doesn't rule. Everything else we know you can at least as closely as you like simulate in a computation what the physical world is doing according to that physical theory. But the one place we don't know that is in this state reduction, the big missing thing in quantum mechanics. And how does then that relate to the phenomenology, what we feel like when we're conscious? Well it doesn't.
Not really. I mean it does in the sense that You see, there are many aspects to consciousness which it doesn't touch. You see, happiness, pain, appreciation of beauty. Well, it does to some degree, but none of these things are very direct.
But the one thing that it does touch is the understanding, the quality of understanding something. Now that quality seems to me, according to the Gödel arguments and so on, that quality is the most important. isn't a computational process. You understand, you stand back, you understand what's going on.
And what does that mean? I don't know. But whatever it means, it is something which requires your awareness. It just doesn't make sense.
to me to say of an entity that it understands something if it's not even aware of it. Just the use of words implies that that involves awareness. Now that's one tiny little ingredient of what awareness is, of what consciousness is. Nevertheless, it's enough, in my view, to make a start.
It doesn't answer all the other questions. You know, what's involved when you perceive the color red or something like that. Certainly those things are not addressed by this.
But at least if you can find one thing, and that's this one thing which is understanding, and in this very limited area of understanding mathematics, only because that's when you can make arguments. There are lots of things where understanding applies, and you can't make rigorous arguments about it. But here is one where you can make rigorous arguments, and those rigorous arguments, it seems to me, pretty clearly... Tell us that our understanding is not a computational process.