How to house a mind inside a brain

The eighteenth‐century French philosopher Voltaire once asked how it was that the great Newtonian heavens conform to the commands of physical law, but there remains in the universe “a little creature five feet tall, acting just as he pleases, solely according to his own caprice?” (Robinson, 1980).The question was rhetorical, of course. A century earlier, Voltaire's compatriot Rene Descartes had famously offered humans an exemption from the natural order, by suggesting that causal principles applied to all intelligent behaviour in animals and all automatic behaviour in humans—such as snatching one's hand out of a flame—but that humans alone possessed a pure thinking substance, a conscious, wilful and rational soul created by God. This soul, Descartes said, directed all voluntary movements of the body, through the so‐called animal spirits. Such thinking could no longer stand, Voltaire insisted. The time had come for humans to discover and acquiesce to their place in the natural scheme of things, regardless of the outcome.Consequences aside, what would it mean, pragmatically, to put humans in their place in nature? From the beginning, the answer seemed clear: there must be no more exceptionalism. The human mind—the consciousness in each of us that peers through telescopes, scribbles calculations, falls in love, practices charity and ponders infinity—must be shown to be a product of the same impersonal forces that command the movements of the planets. This, in turn, meant that the new sciences must explain the functional relationship between human conscious experience and the small lump of living matter housed within the human skull, whose affinity for all things mental had been acknowledged even by Descartes: the human brain.More than two centuries later, Voltaire's challenge still resonates. Today, we have high‐tech brain‐imaging machines, a general theory of the origin of life, a map of the …