How is the mind related to the body?

At one point in the recent film The Imitation Game the detective assigned to his case asks Alan Turing whether machines could think. The dialogue that follows is perhaps not very illuminating philosophically, but it does remind us of an important point: the computer revolution that Turing helped to pioneer gave a huge impetus to interest in what we now call the mind-body problem. In other words, how is the mind related to the body? How could a soggy grey mass such as the brain give rise to the extraordinary phenomenon of consciousness?

The mind-body problem is one of the most controversial issues in philosophy today, and it generates intense passions among the parties to the debate (witness the recent exchange between Galen Strawson and other philosophers in the correspondence columns of the Times Literary Supplement). Some modern philosophers, such as Colin McGinn, believe that the mind-body problem is so intractable that we shall never be able to solve it; we simply don’t possess the concepts necessary to understand how consciousness could emerge from a material system.

When did the mind-body problem arise in philosophy? The computer revolution may have given an impetus to discussion of the issue, but it surely didn’t give birth to it. The usual answer to this question is that a distinctively modern version of the problem arises with Descartes. Despite some recent attempts by scholars to argue that Descartes is the last of the Scholastics, the traditional answer is plausible. Descartes does seem to be the first philosopher to articulate a modern-sounding concept of consciousness, and to ask how such consciousness is related to the brain. Certainly Descartes’ substance dualism sparked a huge debate in the century that followed the publication of his Meditations. The debate may have gone underground at times but in one form or another it has persisted until the present day.

Descartes is in many ways one of us, but in reading his discussions of this issue we are immediately struck by a difference from modern debates. When Descartes and his disciples worry about the mind-body problem, they always have their eyes on theological issues; they seem to be constantly looking over their shoulders to see how the Church will react. In the period of Descartes the mind-body problem was not a freestanding, academic issue; it was intimately bound up with the issue of immortality. Descartes thought that he could ‘sell’ his philosophy to the Catholic Church by showing that his solution to the mind-body problem provided a secure basis for the Christian doctrine of immortality. Materialism, by contrast, seemed to undermine this doctrine.

The related problem of personal identity has a similar history.

Few philosophical problems prove so engaging to students today as the issue of what makes someone the same person over time. And if we ask when this problem got started in philosophy, the traditional answer still seems the right one: the first recognizably modern formulation of the problem is found in Locke’s Essay Concerning Human Understanding. But once again we see how fundamentally the context has changed.

Today the problem of personal identity arises in part by extrapolating from recent developments in biomedical technology: philosophers famously ask what we would say about cases in which one person’s live brain has been successfully transplanted into the body of another human being. The appeal to science fiction, if not the choice of examples, goes back to Locke; Locke himself pioneered the use of such thought-experiments to test our intuitions about personal identity. But Locke’s basic motivation is quite different from that of philosophers today. Locke wants to explain how a person can survive the destruction of the body at death even if there is no persisting immaterial substance. Like Descartes he is worried about what the Church – in his case the Anglican Church – will say in response to his theory.

So the experience of reading the great philosophers of the early modern period can be a strange and disconcerting one. In one way they seem so modern: they address many of the philosophical concerns that we have today. And yet at times in reading them we seem to be in an unfamiliar world where the agenda is a theological one.  We might describe the situation by saying that the seventeenth century is a Janus-faced age: with one face it looks forward to the modern world and with the other it looks back to the middle ages. For many of us that is precisely the source of its endless fascination.