WHAT is consciousness? It is a question that has exercised the minds of neuroscientists and neuro-philosophers for decades – and plain old philosophers for centuries. And it continues to do so. For many – mostly philosophers – consciousness and the related question of the mind is immaterial. In some sense it is not of the material world in which we live but exists outside of our everyday lives. This is what the philosopher Gilbert Ryle described disparagingly as the ‘ghost in the machine’. For others – mostly neuroscientists – it is entirely material.
It is fair to say that most neuroscientists believe that consciousness is part of the physical world. In The Idea of the Brain Matthew Cobb takes as his starting point Francis Crick’s materialist assumption that everything we feel and perceive is ‘in fact no more than the behaviour of a vast assembly of nerve cells and their associated molecules’. Cobb largely agrees with this assumption but concedes that understanding how consciousness emerges remains elusive and is likely to remain so for many decades. That is not to say scientists are thrashing around in the dark. He writes: “Probably the most precise agreed localisation is that the level of consciousness is largely determined by the brainstem and the basal forebrain, while its content – what is being perceived – is processed by the cortex, hypothalamus and so on.”
All this is important because consciousness largely determines who we are and whether or not we have freewill – as our everyday experience tells us we do. The concept of freewill was challenged by a series of experiments by the neuroscientist Benjamin Libet that seemed to show that decisions we think have been taken by our conscious minds have in fact ‘already been taken by your nervous system’. That conclusion has itself been challenged by those who hold that ‘Libet’s experiment holds only if subjects are making arbitrary choices, not if they making important, deliberate decisions’. For example, when you are driving you are normally unaware of the actual process of driving except when you taking action to avoid an accident.
Interestingly, a key element of Cobb’s trawl through the history of brain research is that philosophers and scientists alike have used metaphors to help explain the function of the brain and to prompt further research. Much of this has been fruitful, although, as Cobb points out, there always comes a stage when the understanding that metaphors allow is ‘outweighed by the limits they impose’. Past metaphors have included the brain as a form of clockwork and later as a tree. The current metaphor is the brain as a computer. And Cobb believes that we are approaching the end of the computer metaphor. What is not clear, however, is what will replace it. And of course once we fully understand consciousness – if we ever do – then there will be no need of metaphors.
For now though the computer model remains the dominant one and one of the fruitful lines of enquiry suggests that consciousness is an emergent property which begins its journey in the brain. This involves the claim that the resulting effect – consciousness – is bigger than the sum of its parts and, as Cobb puts it, ‘obeys its own lawfulness’. But one of the problems of the computer model – and most other models for that matter – is that it excludes the environment in which the brain is embedded. Cobb writes: “This might seem trivially obvious, but neither the body nor the environment feature in modelling approaches that seek to understand the brain.” This really is strange because the brain obviously interacts with the body and with the external environment. Indeed, one of the astonishing features of consciousness is the ability to look out from the dark theatre of the skull to observe, interpret and construct the external world. “Excluding these aspects from the model, or from the experimental set-up, will lead at best to an inadequate understanding,” writes Cobb.
The complexity of the brain and the resulting consciousness, mind and sense of Self is such that Cobb believes that we will spend the next century making advances before we have finally solved the riddle. Maybe the various computational projects will come good. “Or a theory will somehow pop out of the vast amounts of imaging data we are generating. Or we will slowly piece together a theory (or theories) out of a series of separate but satisfactory explanations.” Cobb continues like this with several possibilities of the way forward. But just to emphasise the difficulty of the way ahead he finishes the book with simply: “Or…”
Of course, one possibility that Cobb does not countenance is that scientists will never solve the enigma of consciousness. And, maybe, consciousness is not after all a material thing. But at least the scientific approach allows for enquiry, research and the accumulation of evidence – as has and is happening. If, on the other hand, consciousness is an immaterial entity then, by definition, it is not susceptible to scientific enquiry and will remain beyond our understanding for ever.
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