Archive for August, 2004

Picture: Descartes.

Le 'Dennettian Novelist' n'existe pas...

Poor Descartes, as I have remarked before, usually comes in for a ritual denunciation in books about consciousness, blamed for having espoused or even invented dualism, the doctrine of the separation of body and spirit. I think it would be more accurate to see him as presenting a new secular and rational perspective on the conception of the soul which was then prevalent (and to a considerable extent, still is); one which actually narrowed down its sphere of influence to the pineal gland. It seems perverse to me to suggest that later European thinkers got their dualism from Descartes rather than from the common Christian heritage, though that seems to be the way most people see it

But Descartes is relevant to the current debate about consciousness in other ways, too. In particular, I think his most famous argument, the ‘cogito’, challenges some currently-popular perspectives in a way which is well worth considering.

The cogito (‘cogito ergo sum’ – I think, therefore I am) is surely the most well-known argument in philosophy – it occupies the kind of place in its field which the Mona Lisa, Hamlet’s soliloquy, or Beethoven’s Fifth Symphony, occupy in theirs. This kind of mass popularity can, paradoxically become a barrier to proper appreciation. In order to draw out its importance for consciousness, I should like to focus on two points about it: first, it isn’t original; second, it isn’t logical.

Not original, because the same argument can actually be found in St Augustine. I don’t think anyone knows for sure whether Descartes found it there or came up with it independently, but the obvious question is – if St Augustine came up with it first, why aren’t we all talking about St Augustine’s cogito?

The reason, I think, is that the argument was of no great importance to St Augustine. He was in pursuit of faith, not doubt, and was more interested in God’s existence than his own. He puts no particular stress on the cogito argument, and readers who aren’t particularly looking out for it could easily read it without noticing its signficance. For Descartes, by contrast, everything depended on it. He needed a point of certainty from which to begin the construction of his metaphysics: St Augustine already had a source of certainty in God. Descartes also turned to God as a guarantor of knowledge, of course, but in his case, unprecedentedly, God did not come first. In this respect, modern philosophers are mostly in the same boat as Descartes, and if they want certainty, they have to undertake a similar exploration.

Not logical? I don’t, of course, mean that the cogito is illogical, or contains flawed reasoning. But the cogito is often interpreted as a piece of pure logic, an a priori argument whose truth does not depend on observation, like the truths of mathematics. This is a mistake.

Suppose the characters ‘2 + 2 = 4’ were to appear by chance in the pattern of clouds in the sky: the statement they represent would still be true. But if the clouds somehow lined up to form the words ‘cogito ergo sum’, it would be false – the clouds are not doing any thinking. Descartes is not offering a logical proof, but making a claim that certain kinds of perception, or thought, are immune from error. In particular, when I perceive my own existence, I cannot be wrong, because if I didn’t exist no perceiving would be going on. Even doubting my own existence actually proves it, because only entities which exist can doubt their own reality.

There may be just a few other perceptions which have a similar immunity from error. Arguably, you can’t be wrong about being in pain, for example, though you might be wrong about the existence of the dentist. But I digress…

The point here is that if you’re looking for philosophical certainty, and you can’t get it from God, it can only be found in the first-person view, and in the self. But the first-person view, and the reality of the self, are just what many modern thinkers about consciousness would want to do without. These days, we look to empirical science for the truth, and distrust our own inner phenomenal experience, although all our knowledge of the world, and of science, actually derives in the final analysis from interpretation of our own subjective phenomenal experiences (doesn’t it?).

It wasn’t always quite like this. In Brentano’s day it was natural to think that the business of psychology included the classification and study of one’s own inner, subjective sensations: but the disastrous over-development and subsequent collapse of introspectionist psychology functioned like a nuclear explosion, not merely destroying the existing structures, but rendering the whole territory of phenomenal experience uninhabitable and even unvisitable for a generation. During the era of Behaviourism, subjective experience and even consciousness itself was actually denied as a result. Those days have passed, but many still feel that if something can’t be investigated from the third-person point of view, it can’t be brought within respectable science at all.

I suppose this epitomises the dilemma of consciousness as it exists today: direct, first-person investigation of phenomenal experience seems to lead nowhere, but certain key aspects of consciousness – qualia, meaning, selfhood, and so on – seem to have no place in the objective third-person account.

Some, of course, are bold enough to offer eliminative accounts of these intractable phenomena: for them, the Cartesian suggestion that all knowledge ultimately springs from phenomenal experience must surely be profoundly unpalatable. Could this be one of the reasons why Descartes keeps getting such a drubbing?

Picture: Twin Earth. Blandula Once upon a time (1750, in fact – or in any case, some time before the development of modern chemistry) there were two very similar planets. One was Earth: the other was also called Earth, but to save confusion let’s call it Twin Earth. The general size, geography, climate and biology of Twin Earth were all pretty much like those of Earth – in fact, the two planets were virtually indistinguishable, with each person having an identical twin on the other planet.

However, there was one particular difference. On Twin Earth, the transparent liquid which made up the seas, lakes and rivers, which the animals drank, and which fell as rain – the substance, in fact, which the locals called ‘water’ – was not H2O, but XYZ. In most respects, and without resort to more sophisticated chemistry, it was impossible to spot any difference between the qualities and behaviour of XYZ and those of H2O.

(At this point, scientifically inclined readers may look worried and begin saying things like ‘Yeah, but look… it couldn’t be exactly the same as real water’. Well no, not really: with a bit of thought we could probably find a more plausible version, but H2O versus XYZ was what Hilary Putnam originally chose, and it doesn’t really affect the argument.)

The strange result is that when Robinson, on Earth, thinks about the contents of his glass, he is thinking about H2O. But when Twin-Earth Robinson thinks an exactly similar thought, with exactly similar brain states, he is thinking about XYZ. The difference in what they are thinking about arises entirely from differences in the external world, not from any difference in the two brains. In the words of Putnam’s famous slogan ‘meaning isn’t in the head’.

In one way, this doesn’t seem so surprising: it seems almost common sense that meaning is affected by context. On the other hand, it seems a natural assumption that what you think about is pretty much under your own control, something you arrange for yourself within your own skull irrespective of the outside world. The Twin Earth argument undercuts the idea that meaning can arise from mental images or representations alone, which raises a difficulty for anyone wanting to endow a computer with consciousness, and anyone applying a functionalist interpretation to human consciousness. Computational representations in one’s head cannot, it seems, be the same thing as psychological propositions in one’s mind, at least not without some further ingredient.

Bitbucket The problem is illusory. Dennett sees this. First, he suggests, consider the behaviour of the coin-recognising mechanism in a slot machine. It may have been designed for American coins, but what if it is put to work ‘recognising’ Panamanian quarter-balboas (which are the same shape and weight). Do we say the machine is still (mistakenly) recognising US quarters, or has it somehow switched over to being a quarter-balboa recogniser? Who cares? If we like we can say that the intention of the designer means that the machine is still a US-quarter-recogniser, or equally, that the person who installed it in Panama has effectively transformed it into a ‘q-balber’ instead. In the end, we can interpret it whichever way suits us, can’t we?

OK then. Now consider Twin Earth. Let’s suppose, instead of the water case, we think about horses. On Twin Earth, let’s say, they have schmorses instead; animals which resemble horses closely apart from genetics and some internal details. If some helpful philosophical aliens transport Robinson from Earth to Twin Earth, and he sees a schmorse, what does he mean when he says ‘there’s a horse’? Does he still mean ‘horse’, or does he now really mean ‘schmorse’?

Isn’t this the same as the coin machine? Horse, schmorse, what’s the difference?

Blandula But the two cases aren’t the same. It’s OK to decide arbitrarily in the case of the coin machine, because the coin machine doesn’t mean to identify any particular coin. It does whatever we intend it to do. But my thoughts don’t depend on how you interpret my behaviour. The machine only has derived intentionality – any meanings come from the designer or user. But people have real, original intentionality. When I mean something, I mean it all by myself, irrespective of how other people may construe my meaning.

Bitbucket Ah, but that’s just where you’re wrong, and that’s what Dennett explicitly denies. On your argument, meanings must remain forever a magic mystery: if you want a rational explanation, you have to accept that original, intrinsic meaningfulness is absurd. How can anything, even a brain, mean anything intrinsically?

Blandula I might ask, if all intentionality is derived, where does it ultimately come from? Dennett seems to think we can generate it from nothing by, as it were, taking in each other’s washing. But if there’s one thing that’s clear to me, it is that the meaning of my thoughts doesn’t in itself depend on other people’s interpretations. I’ll agree that Dennett is right about one thing though – this is one of the key issues, where people’s intuitions divide sharply – almost as if they were on different planets…

Picture: Francis Crick. The death of Francis Crick at the end of last month drew many eulogies, most of which naturally highlighted the discovery of the double helix structure of DNA. In the latter part of his life, however, Crick turned his attention to the problem of consciousness rather than genetics or microbiology. He seems to have been temperamentally inclined to working in collaboration with a partner – having cracked the mystery of DNA with Watson, he now developed a fruitful partnership with Christof Koch. His view of consciousness, however, was summed up in his own book ‘The Astonishing Hypothesis’.

The hypothesis in question is ‘…that “You”, your joys and your sorrows, your memories and your ambitions, your sense of personal identity and free will, are in fact no more than the behaviour of a vast assembly of nerve cells and their associated molecules.’

It has been suggested by some that this is not such an astonishing hypothesis after all. Certainly the idea that our mental life arises from the activity of the brain has been a mainstream one for a considerable time, but the key words in Crick’s hypothesis are perhaps ‘no more than’. On the face of it, this is indeed a fairly extreme claim; a reductionism which stops just short of denying the actual existence of consciousness. The quotation marks around the word ‘You’ suggest that Crick was also tempted by scepticism about the self.

It’s difficult to be absolutely clear about Crick’s philosophical position, however. Searle criticised ‘The Astonishing Hypothesis’ for not being clear about exactly what kind of reductionism it was putting forward, and with some justice: at times Crick talks in terms of emergence, and he seems to want to disavow naive or eliminativist reductionism, but his bottom line does seem to be that consciousness is nothing more than the activity of neurons.

One reason for this lack of clarity is perhaps that Crick, as he very fairly points out, is not even trying to set out a finished theory, only a hypothesis and a suggested line of attack. But the fundamental reason is that Crick is really interested in telling a scientific story, not a philosophical one. Most of the book is taken up with doing this. Crick’s strategy is to approach consciousness via a consideration of the faculty of vision. He gives a very clear and interesting account of research in this area, with a well-judged balance of speculation and caution. Personally, however, I think the focus on vision dooms the enterprise from the start, at least as far as consciousness is concerned. The best one can hope to get by investigating vision alone is some insight into attention and sensory awareness; the central issues of consciousness are likely to remain untouched. Blind people are fully conscious, after all!

It’s also true that Crick’s close focus on neurons at the expense of philosophy seems to lead him into some dubious positions. He and Koch are particularly known for the view that consciousness arises when sets of neurons fire in a co-ordinated way, at frequencies around 40 Hertz. Crick suggests that synchronised firing of this kind might, in particular, be the neural correlate of visual awareness. To be really consistent with Crick’s general attitude, the firing really needs to be visual awareness, not just correlated with it, but that is perhaps a nit-picking point: the more fundamental difficulty is that no explanation is ever offered as to why co-ordinated firing should give rise to conscious experience. Crick suggests that this kind of co-ordination might be the answer to the notorious binding problem, because it explains how neurons in different visual areas which respond to different qualities of the seen object (form colour, motion, etc) ‘temporarily become active as a unit’, but it seems that at best that might be part of the answer. A particularly difficult aspect of the problem is that different pieces of sensory data which relate to the same object don’t arrive in one place in the brain at the same time, yet our conscious experience never seems to suffer from, as it were, faulty lip sync. It’s hard to see how simultaneous patterns of firing could deal with the chronological problem.

At the end of the book, Crick offers a short and tentative postscript setting out an idea about free will. This is really an explanation for why people think they have free will – Crick is presumably a determinist. His idea is that there is an unconscious part of the brain which makes the plans for what we are going to do: these plans then pop into the conscious mind as if from nowhere, giving an impression of free will. The conscious mind may be able to guess the factors behind the plans, or it may get them wrong: either way, it feels there is some mystery about the process. Crick, drawing on some research by Damasio, goes so far as to suggest that this unconscious planning facility (the ‘seat of the will’) is probably located in or near the anterior cingulate sulcus.

Of course it is perfectly true that the processes which give rise to conscious thought are not themselves conscious (otherwise we should be caught in a vicious regress), but that does not imply that consciousness is not in the driving seat. Often when we make a complex decision or draw up an explicit plan, we weigh the factors and consider possible events consciously in our minds, and it seems very hard to believe that this kind of process, which surely bears a remarkable resemblance to decision-making, is not ultimately responsible for the plan or decision which is eventually arrived at. Indeed, I think most people believe that making decisions and plans, and allowing human beings to rise above the influence of their immediate current environment, is exactly what consciousness is for.

As Crick himself would probably have been the first to agree, ‘The Astonishing Hypothesis’ is not the place to look for philosophy: but ten years after publication, in a fast moving field, it is still worth reading.