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beginning it was clear that there was simply ‘too much going on’. There could be no simpler experiment than to scan the brain of a subject when first reading, then speaking, then listening to, a single word such as ‘chair’. This should, it was anticipated, show the relevant part of the brain ‘lighting up’ – the visual cortex when reading, the speech centre when speaking, and the hearing cortex when listening. But no, the brain scan showed that each separate task ‘lit up’ not just the relevant part of the brain, but generated a blizzard of electrical activity across vast networks of millions of neurons – while thinking about the meaning of a word and speaking appeared to activate the brain virtually in its entirety. The brain, it seemed, must work in a way previously never really appreciated – not as an aggregate of distinct specialised parts, but as an integrated whole, with the same neuronal circuits performing many different functions.

      The initial surprise at discovering how the brain fragmented the sights and sounds of the world ‘out there’ into a myriad of separate components grew greater still as it became clear that there was no compensating mechanism that might reintegrate all those fragments back together again into that personal experience of being at the centre, moment by moment, of a coherent, ever-changing world. Reflecting on this problem of how to ‘bind’ all the fragments back together again, Nobel Prize-winner David Hubel of Harvard University observed:

      This abiding tendency for attributes such as form, colour and movement to be handled by separate structures in the brain immediately raises the question how all the information is finally assembled, say for perceiving a bouncing red ball. It obviously must be assembled – but where and how, we have no idea.

      But the greatest perplexity of all was the failure to account for how the monotonous electrical activity of those billions of neurons in the brain translate into the limitless range and quality of subjective experiences of our everyday lives – where every transient, fleeting moment has its own distinct, unique, intangible feel: where the cadences of a Bach cantata are so utterly different from the flash of lightning, the taste of Bourbon from the lingering memory of that first kiss.

      The implications are clear enough. While theoretically it might be possible for neuroscientists to know everything there is to know about the physical structure and activity of the brain, its ‘product’, the mind, with its thoughts and ideas, impressions and emotions, would still remain unaccounted for. As the philosopher Colin McGinn expresses it:

      Suppose I know everything about your brain: I know its anatomy, its chemical ingredients, the pattern of electrical activity in its various segments, I even know the position of every atom and its subatomic structure. Do I therefore know everything about your mind? It certainly seems not. On the contrary, I know nothing about your mind. So knowledge of your brain does not give me knowledge of your mind.

      This distinction between the electrical activity of the material brain and the non-material mind (of thoughts and ideas) as two quite different things might seem so self-evident as to be scarcely worth commenting on. But for neuroscientists the question of how the brain’s electrical activity translates into thoughts and sensations was precisely what needed explaining – and their failure to do so has come to haunt them. So, for everything that the Decade of the Brain undoubtedly achieved, nonetheless, as John Maddox, editor of Nature, would acknowledge at its close: ‘We seem as far from understanding [the brain] as we were a century ago. Nobody understands how decisions are made or how imagination is set free.’

      This verdict on the disappointing outcomes of the Genome Project and the Decade of the Brain might seem a trifle premature. These are, after all, still very early days, and it is far too soon to predict what might emerge over the next twenty to thirty years. The only certainty about advances in human knowledge is that they open the door to further seemingly unanswerable questions, which in time will be resolved, and so on. The implication that here science may finally have ‘reached its limits’ would seem highly contentious, having been expressed many times in the past, only to be repeatedly disproved. Famously, the physicist Lord Kelvin, at the close of the nineteenth century, insisted that the future of his discipline was to be looked for in ‘the sixth place of decimals’ (that is, futile refinements of the then present state of knowledge). Within a few years Albert Einstein had put forward his General Theory of Relativity, and the certainties of Lord Kelvin’s classical physics were eclipsed.

      The situation here, however, is rather different, for while the New Genetics and those novel brain scanning techniques offer almost inexhaustible opportunities for further research, it is possible to anticipate in broad outline what their findings will add up to. Scientists could, if they so wished, spell out the genomes of each of the millions of species with which we share this planet – snails, bats, whales, elephants and so on – but that would only confirm that they are composed of several thousand similar genes that ‘code’ for the nuts and bolts of the cells of which they are made, while the really interesting question, of how those genes determine the unique form and attributes of the snail, bat, elephant, whale or whatever, would remain unresolved. And so too for the scanning techniques of the neurosciences, where a million scans of subjects watching a video of bouncing red balls would not take us an iota further in understanding what needs explaining – how the neuronal circuits experience the ball as being red and round and bouncing.

      At any other time these twin setbacks to the scientific enterprise might simply have been relegated to the category of problems for which science does not as yet have the answer. But when cosmologists can reliably infer what happened in the first few minutes of the birth of the universe, and geologists can measure the movements of vast continents to the nearest centimetre, then the inscrutability of those genetic instructions that should distinguish a human from a fly, or the failure to account for something as elementary as how we recall a telephone number, throws into sharp relief the unfathomability of ourselves. It is as if we, and indeed all living things, are in some way different, profounder and more complex than the physical world to which we belong.

      Nonetheless there must be a reason why those genome projects proved so uninformative about the form and attributes of living things, or why the Decade of the Brain should have fallen so far short of explaining the mind. There is a powerful impression that science has been looking in the wrong place, seeking to resolve questions whose answers lie somehow outside its domain. This is not just a matter of science not yet knowing all the facts; rather there is the sense that something of immense importance is ‘missing’ that might transform the bare bones of genes into the wondrous diversity of the living world, and the monotonous electrical firing of the neurons of the brain into the vast spectrum of sensations and ideas of the human mind. What might that ‘missing’ element be?

      Much of the prestige of science lies in its ability to link together disparate observations to reveal the processes that underpin them. But this does not mean that science ‘captures’ the phenomena it describes – far from it. There is, after all, nothing in the chemistry of water (two atoms of hydrogen to one of oxygen) that captures its diverse properties as we know them to be from personal experience: the warmth and wetness of summer rain, the purity and coldness of snow in winter, the babbling brook and the placid lake, water refreshing the dry earth, causing the flowers to bloom and cleansing everything it touches. It is customary to portray this distinction as ‘two orders of reality’. The ‘first’ or ‘primary reality’ of water is that personal knowledge of its diverse states and properties that includes not just how we perceive it through our senses, but also the memories, emotions and feelings with which we respond to it. By contrast, the ‘second order reality’ is water’s materiality, its chemical composition as revealed by the experimental methods of the founder of modern chemistry, the French genius Antoine Lavoisier, who in 1783 sparked the two gases of hydrogen and oxygen together in a test tube, to find a residue of dew-like drops that ‘seemed like water’.

      These two radically different, yet complementary, ‘orders of reality’ of water are mutually exclusive. There is nothing in our personal experience that hints at water’s chemical composition, nor conversely is there anything in its chemical formula that hints at its

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