Modern Mind

consciousness has been very much the flavour of the decade, and it is fair to say that those involved in the subject fall into four camps. There are those, like the British philosopher Colin McGinn, who argue that consciousness is resistant to explanation
in principle
and for all time. 79 Philosophers we have met before – such as Thomas Nagel and Hilary Putnam – also add that at the present (and maybe for all time) science cannot account for qualia, the first-personphenomenal experience that we understand as consciousness. Then there are two types of reductionist. Those like Daniel Dennett, who claim not only that consciousness can be explained by science but that construction of an artificially intelligent machine that will be conscious is not far off, may be called the ‘hard’ reductionists. 80 The soft reductionists, typified by John Searle, believe that consciousness does depend on the physical properties of the brain but think we are nowhere near solving just how these processes work, and dismiss the very idea that machines will ever be conscious. 81 Finally, there are those like Roger Penrose who believe that a new kind of dualism is needed, that in effect a whole new set of physical laws may apply inside the brain, which account for consciousness. 82 Penrose’s particular contribution is that quantum physics operate within tiny structures, known as tubules, within the nerve cells of the brain to produce – in some as yet unspecified way – the phenomena we recognise as consciousness. 83 Penrose actually thinks that we live in three worlds – the physical, the mental, and the mathematical: ‘The physical world grounds the mental world, which in turn grounds the mathematical world and the mathematical world is the ground of the physical world and so on around the circle.’ 84 Many people, who find this tantalising, nonetheless don’t feel Penrose has
proved
anything. His speculation is enticing and original, but it is still speculation.
    Instead, it is the two forms of reductionism that in the present climate attract most interest. For people like Dennett, human consciousness and identity arise from the narrative of their lives, and this can be related to specific brain states. For example, there is growing evidence that the ability to ‘apply intentional predicates to other people is a human universal’ and is associated with a specific area of the brain (the orbitofrontal cortex); in certain states of autism, this ability is defective. There is also evidence that the blood supply to the orbitofrontal cortex increases when people ‘process’ intentional verbs as opposed to non-intentional ones, and that damage to this area of the brain can lead to a failure to introspect. 85 Suggestive as this is, it is also the case that the microanatomy of the brain varies quite considerably from individual to individual, and that a particular phenomenal experience is represented at several different points in the brain, which clearly require integration. Any ‘deep’ patterns relating experience to brain activity have yet to be discovered, and seem to be a long way off, though this is still the most likely way forward.
    A related approach – perhaps to be expected, given other developments in recent years – is to look at the brain and consciousness in a Darwinian light. In what sense is consciousness adaptive? This approach has produced two views – one that the brain was in effect ‘jerry-built’ in evolution to accomplish very many and very different tasks. On this view, there are at base three organs: a reptilian core (the seat of our basic drives), a palaeomammalian layer, which produces such things as affection for offspring, and a neomammalian brain, the seat of reasoning, language, and other ‘higher functions.’ 86 The second approach is to argue that throughout evolution (and throughout our bodies) there have been emergent properties: for example, there is always a biochemical explanation underlying a physiological phenomenon – sodium/potassium fluxacross a membrane being also nerve action potential. 87 In this sense, then, consciousness is nothing new in principle even if, at the moment, we don’t fully understand it.
    Studies of nerve action through the animal kingdom have also shown that nerves work by either firing or not firing; intensity is represented by the rate of firing – the more intense the stimulation, the faster the turning on and off of any particular nerve. This of