The Incredible Consciousness of Edward Witten

Edward WittenWe’ll never understand consciousness, says Edward Witten. Ashutosh Jogalekar’s post here features a video of the eminent physicist talking about fundamentals; the bit about consciousness starts around 1:10 if you’re not interested in string theory and cosmology. John Horgan has also weighed in with some comments; Witten’s view is congenial to him because of his belief that science may be approaching an end state in which many big issues are basically settled while others remain permanently mysterious. Witten himself thinks we might possibly get a “final theory” of physics (maybe even a form of string theory), but guesses that it would be of a tricky kind, so that understanding and exploring the theory would itself be an endless project, rather the way number theory, which looks like a simple subject at first glance, proves to be capable of endless further research.

Witten, in response to a slightly weird question from the interviewer, declines to define consciousness, saying he prefers to leave it undefined like one of the undefined terms set out at the beginning of a maths book. He feels confident that the workings of the mind will be greatly clarified by ongoing research so that we will come to understand much better how the mechanisms operate. But why these processes are accompanied by something like consciousness seems likely to remain a mystery; no extension of physics that he can imagine seems likely to do the job, including the kind of new quantum mechanics that Roger Penrose believes is needed.

Witten is merely recording his intuitions, so we shouldn’t try to represent him as committed to any strong theoretical position; but his words clearly suggest that he is an optimist on the so-called Easy Problem and a pessimist on the Hard one. The problem he thinks may be unsolvable is the one about why there is “something it is like” to have experiences; what it is that seeing a red rose has over and above the acquisition of mere data.

If so, I think his incredulity joins a long tradition of those who feel intuitively that that kind of consciousness just is radically different from anything explained or explainable by physics. Horgan mentions the Mysterians, notably Colin McGinn, who holds that our brain just isn’t adapted to understanding how subjective experience and the physical world can be reconciled; but we could also invoke Brentano’s contention that mental intentionality is just utterly unlike any physical phenomenon; and even trace the same intuition back to Leibniz’s famous analogy of the mill; no matter what wheels and levers you put in your machine, there’s never going to be anything that could explain a perception (particularly telling given Leibniz’s enthusiasm for calculating machines and his belief that one day thinkers could use them to resolve complex disputes). Indeed, couldn’t we argue that contemporary consciousness sceptics like Dennett and the Churchlands also see an unbridgeable gap between physics and subjective, qualia-having consciousness? The difference is simply that in their eyes this makes that kind of consciousness nonsense, not a mystery.

We have to be a bit wary of trusting our intuitions. The idea that subjective consciousness arises when we’ve got enough neurons firing may sound like the idea that wine comes about when we’ve added enough water to the jar; but the idea that enough ones and zeroes in data registers could ever give rise to a decent game of chess looks pretty strange too.

As those who’ve read earlier posts may know, I think the missing ingredient is simply reality. The extra thing about consciousness that the theory of physics fails to include is just the reality of the experience, the one thing a theory can never include. Of course, the nature of reality is itself a considerable mystery, it just isn’t the one people have thought they were talking about. If I’m right, then Witten’s doubts are well-founded but less worrying than they may seem. If some future genius succeeds in generating an artificial brain with human-style mental functions, then by looking at its structure we’ll only ever see solutions to the Easy Problem, just as we may do in part when looking at normal biological brains. Once we switch on the artificial brain and it starts doing real things, then experience will happen.

Reality

knight 4This is the last of four posts about key ideas from my book The Shadow of Consciousness, and possibly the weirdest; this time the subject is reality.

Last time I suggested that qualia – the subjective aspect of experiences that gives them their what-it-is-like quality – are just the particularity, or haecceity, of real experiences. There is something it is like to see that red because you’re really seeing it; you’re not just understanding the theory, which is a cognitive state that doesn’t have any particular phenomenal nature. So we could say qualia are just the reality of experience. No mystery about it after all.

Except of course there is a mystery – what is reality? There’s something oddly arbitrary about reality; some things are real, others are not. That cake on the table in front of me; it could be real as far as you know; or it could indeed be that the cake is a lie. The number 47, though, is quite different; you don’t need to check the table or any location; you don’t need to look for an example, or count to fifty; it couldn’t have been the case that there was no number 47. Things that are real in the sense we need for haecceity seem to depend on events for their reality. I will borrow some terminology from Meinong and call that dependent or contingent kind of reality existence, while what the number 47 has got is subsistence.

What is existence, then? Things that exist depend on events, I suggested; if I made a cake and put it in the table, it exists; if no-one did that, it doesn’t. Real things are part of a matrix of cause and effect, a matrix we could call history. Everything real has to have causes and effects. We can prove that perhaps, by considering the cake’s continuing existence. It exists now because it existed a moment ago; if it had no causal effects, it wouldn’t be able to cause its own future reality, and it wouldn’t be here. If it wasn’t here, then it couldn’t have had preceding causes, so it didn’t exist in the past either. Ergo, things without causal effects don’t exist.

Now that’s interesting because of course, one of the difficult things about qualia is that they apparently can’t have causal effects. If so, I seem to have accidentally proved that they don’t exist! I think things get unavoidably complex here. What I think is going on is that qualia in general, the having of a subjective side, is bestowed on things by being real, and that reality means causal efficacy. However, particular qualia are determined by the objective physical aspects of things; and it’s those that give specific causal powers. It looks to us as if qualia have no causal effects because all the particular causal powers have been accounted for in the objective physical account. There seems to be no role for qualia. What we miss is that without reality nothing has causal powers at all.

Let’s digress slightly to consider yet again my zombie twin. He’s exactly like me, except that he has no qualia, and that is supposed to show that qualia are over and above the account given by physics. Now according to me that is actually not possible, because if my zombie twin is real, and physically just the same, he must end up with the same qualia. However, if we doubt this possibility, David Chalmers and others invite us at least to accept that he is conceivable. Now we might feel that whether we can or can’t conceive of a thing is a poor indicator of anything, but leaving that aside I think the invitation to consider the zombie twin’s conceivability draws us towards thinking of a conceptual twin rather than a real one. Conceptual twins – imaginary, counterfactual, or non-existent ones – merely subsist; they are not real and so the issue of qualia does not arise. The fact that imaginary twins lack qualia doesn’t prove what it was meant to; properly understood it just shows that qualia are an aspect of real experience.

Anyway, are we comfortable with the idea of reality? Not really, because the buzzing complexity and arbitrariness of real things seems to demand an explanation. If I’m right about all real things necessarily being part of a causal matrix, they are in the end all part of one vast entity whose curious firm should somehow be explicable.

Alas, it isn’t. We have two ways of explaining things. One is pure reason: we might be able to deduce the real world from first principles and show that it is logically necessary. Unfortunately pure reason alone is very bad at giving us details of reality; it deals only with Platonic, theoretical entities which subsist but do not exist. To tell us anything about reality it must at least be given a few real facts to work on; but when we’re trying to account for reality as a whole that’s just what we can’t provide.

The other kind of explanation we can give is empirical; we can research reality itself scientifically and draw conclusions. But empirical explanations operate only within the causal matrix; they explain one state of affairs in terms of another, usually earlier one. It’s not possible to account for reality itself this way.

It looks then, as if reality is doomed to remain at least somewhat mysterious, unless we somehow find a third way, neither empirical nor rational.

A rather downbeat note to end on, but sincere thanks to all those who have helped make the discussion so interesting so far…

The Stove of Consciousness

I’ve been reading A.C. Grayling’s biography of Descartes: he advances the novel theory that Descartes was a spy. This is actually a rather shrewd suggestion which makes quite a lot of sense given Descartes’ wandering, secretive life. On balance I think he probably wasn’t conducting secret espionage missions – it’s unlikely we’ll ever know for sure, of course – but I think it’s certainly an idea any future biographer will have to address.

I was interested, though, to see what Grayling made of the stove.  Descartes himself tells us that when held up in Germany by the advance of winter, he spent the day alone in a stove, and that was where his radical rebuilding of his own beliefs began.  This famous incident has the sort of place in the history of philosophy that the apple falling on Newton’s head has in the history of science: and it has been doubted and queried in a similar way. But Descartes seems pretty clear about it: “je demeurais tout le jour enfermé seul dans un poêle, où j’avais tout le loisir m’entretenir de mes pensées”.

Some say it must in fact have been a bread-oven or a similarly large affair: Descartes was not a large man and he was particularly averse to cold and disturbance, but it would surely have to have been a commodious stove for him to have been comfortable in there all day. Some say that Bavarian houses of the period had large stoves, and certainly in the baroque palaces of the region one can see vast ornate ones that look as if they might have had room for a diminutive French philosopher. Some commonsensical people say that “un poêle” must simply have meant a stove-heated room; and this is in fact the view which Grayling adopts firmly and without discussion.

Personally I’m inclined to take Descartes’ words at face value; but really the question of whether he really sat in a real stove misses the point. Why does Descartes, a rather secretive man, even mention the matter at all? It must be because, true or not, it has metaphorical significance; it gives us additional keys to Descartes’ meaning which we ought not to discard out of literal-mindedness. (Grayling, in fairness, is writing history, not philosophy.)

For one thing Descartes’ isolation in the stove functions as a sort of thought-experiment. He wants to be able to doubt everything, but it’s hard to dismiss the world as a set of illusions when it’s battering away at your senses: so suppose we were in a place that was warm, dark, and silent?  Second, it recalls Plato’s cave metaphor. Plato had his unfortunate exemplar chained in a cave where his only knowledge of the world outside came from flickering shadows on the wall; he wanted to suggest that what we take to be the real world is a similarly poor reflection of a majestic eternal reality. Descartes wants to work up a similar metaphor to a quite different conclusion, ultimately vindicating our senses and the physical world; perhaps this points up his rebellion against ancient authority. Third, in a way congenial to modern thinking and probably not unacceptable to Descartes, the isolation in the stove resembles and evokes the isolation of the brain in the skull.

The stove metaphor has other possible implications, but for us the most interesting thing is perhaps how it embodies and possibly helped to consolidate one of the most persistent metaphors about consciousness, one that has figured strongly in discussion for centuries, remains dominant, yet is really quite unwarranted. This is that consciousness is internal. We routinely talk about “the external world” when discussing mental experience. The external world is what the senses are supposed to tell us about, but sometimes fail to; it is distinct from an internal world where we receive the messages and where things like emotions and intentions have their existence. The impression of consciousness being inside looking out is strongly reinforced by the way the ears and the brain seem to feed straight into the brain: but we know that impression of being located in the head would be the same if human anatomy actually put the brain in the stomach, so long as the eyes and ears remained where they are. In fact our discussions would make just as much sense if we described consciousness as external and the physical world as internal (or consciousness as ‘above’ and the physical world as ‘below’ or vice versa)

If we take consciousness to be a neural process there is of course, a sense in which it is certainly in the brain; but only in the sense that my money is in the bank’s computer (though I can’t get it out with a hammer) or Pride and Prejudice is in the pages of that book over there (and not, after all, in my head). Strictly or properly, stories and totals don’t have the property of physical location, and nor, really, does consciousness.

Does it matter if the metaphor is convenient? Well, it may well be that the traditional inside view encourages us to fall into certain errors. It has often been argued (and still is) for example that because we’re sometimes wrong about what we’re seeing or hearing, we must in fact only ever see an intermediate representation, never the  real world itself. I think this is a mistake, but it’s one that the internal/external view helps to make plausible.  It may well be, in my opinion, that habitually thinking of consciousness as having a simple physical location makes it more difficult for us to understand it properly.

So perhaps we ought to make a concerted effort to stop, but to be honest I think the metaphor is just too deeply rooted. At the end of the day you can take the thinker out of the stove, but you can’t take the stove out of the thinker.