Physics of Consciousness - David Wallace

David Wallace

David Wallace is a philosopher of physics at the Philosophy School of the University of Southern California, after twenty-two years at the University of Oxford as a student, researcher and faculty.

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David
Wallace

Philosopher of Physics, University of Southern California

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Robert Lawrence Kuhn:

David, as a philosopher of physics, what do you think of the efforts of recent times, particularly here at the FQXI conference, to elicit advanced ideas in physics, particularly quantum physics and different structures, to explain consciousness as being something other than the, just the simple biological emergence of what happens macroscopically among neurons in the brain.

David Wallace:

Sure. It's always kind of difficult because some of the smartest people I know and some pretty good friends take these approaches very seriously. I find it very difficult to take it seriously at all. It seems that we don't think we need a fundamental physics of digestion or fundamental physics of respiration, even though these are difficult biological processes that we're really lacking a root for. Consciousness people seem to think is different and the reasons they think it's different, I think, are intuitions and hunches, which can feel very plausible, but when you really interrogate them, are hard to sustain.

Robert Lawrence Kuhn:

Well, I think it's obvious that, as one famous philosopher said, the consciousness is an output of the brain as urine is an output of the kidney. Now, the difference is, and it's very complicated how the kidney filters and all of that, and the other organs as well. The difference is the phenomenological inner movie, the inner subjectivity that we all know that I have, as an individual, and I infer that you do, but you know, I can never know that you could be...everybody else in this world could be an inner zombie, as we say, and I could be the only one conscious. We'll never know that. But that phenomenon is a radical difference, isn't it?

David Wallace:

Well, you say that. You've passionately made that case, but assuming that this consciousness is not actually kicking the electrons and atoms around your brain, and almost no one thinks it is, then you'd have made just as passionate the case, just as convincing if you're one of these zombies.

Robert Lawrence Kuhn:

No. For certain, that's absolutely true, but that argument can be utilized that, because I'm knowing it myself, therefore, and anybody else, and you could envision a zombie doing that for exactly the reason that you said. Therefore, there has to be something else. That argument is used exactly the reverse.

David Wallace:

I don't think you can envisage it. I mean, what you're doing when you're envisaging it is you've got a sort of picture in your mind of a person or a robot or whatever and then you're just thinking to yourself, well, that's not conscious, but you don't know that. I mean, by analogy, and this is an analogy of Dan Dennett's, but I could imagine a cell that wasn't alive. Here's me doing it now. I'm imaging a cell, vivid detail, then I'm thinking this cell isn't alive, but that doesn't really mean that I've imagined an un-alive cell. I just haven't thought enough about it. It turns out, if you think really hard about how that cell works, it's living.

Robert Lawrence Kuhn:

You made a point that, and seemed to think it was self-evident, which to me it's not, that consciousness can't interact. That's one of a whole series of theories of consciousness and philosophy of mind, that consciousness in an epiphenomenon, that it sort of is the foam on the wave. It doesn't cause anything, but it just rides along the surface. That's just one theory. It may be right, but you can't dismiss all the other theories.

David Wallace:

Well, let's try it. Let's suppose that there really was a new substance, a consciousnessite, which is not described at all by any physicality we have so far, but actually, when we look really hard at the brain, we find that our – we get a much better theory if we recognize that the electrons are being pushed around by the consciousnessite and we do lots of experiments to support this. Okay, fine. Now somebody comes along and says I can imagine somebody whose brain is just the same and had all the same consciousnessite, but wasn't conscious, and then the question just goes to one regress further. Anything that we're describing in the language of interactions and dynamics is equally open to this objection that says, well, I can imagine all that going on without consciousness. So if you think that objection works, you don't really improve things by supposing there's an interaction.

Robert Lawrence Kuhn:

Okay, but you're, I think you're still left with the primary problem, which is the phenomenal, phenomenology of what we feel and see being a step function different, being a radical difference from everything else we know in the universe.

David Wallace:

How is it different?

Robert Lawrence Kuhn:

It's different because if I, if I stub my toe and we see lots of spikes along the C fibers that go to a certain part of my brain, that's one thing and my intense feeling of pain, and knowing what it's like to feel that is a radically different thing. Now, you can correlate them perfectly and that's why many people have come up with an identity theory, which in a sense is a perfect scientific answer, but it seems conceptually absurd to say that my pain is this. They're correlated, but the feeling of the pain versus just seeing sodium ions and potassium ions going through membranes and all that, I mean, it's radically different categories.

David Wallace:

We have a really deep intuition that these are radically different, and I share that intuition. What I don't think we have is anything that goes beyond that intuition. We don't have an argument. We don't have a deduction that says these are not the same things and attempts to get it just mean more intuitions come up and I just don't think intuitions are a great route to truth in science. Lots of things are really counterintuitive. It's really, really counterintuitive that your pain literally is a whole bunch of electrical, structural, and functional goings-on in the brain, but the fact is not counterintuitive, that it's counterintuitive doesn't make it false.

Robert Lawrence Kuhn:

So, what...what...the conclusion of what you would say is that we live in a universe, in a structure of existence, where it is possible for electrical activities to literally be the feeling of consciousness?

David Wallace:

I don't think we live in a universe where it's possible; I think we live in a universe where it's actual.