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.