Philosophy began for me, as for many others, from the smallest word in the language: the word “I”. What on earth does this word stand for? Does it stand for something, but for nothing on earth? Am I distinct from my body, or just a part of it? Is the “self” idea a grammatical illusion, a misreading of the logic of “I”? Such questions have been thrown into relief by neurologists like Oliver Sacks, who describe the terrible distortions of the “I” that follow when this or that area of the central nervous system is damaged or diseased. And the role of the brain in our mental processes has been underlined by new techniques, such as MRI (magnetic resonance imaging), for tracing heightened activity in the central nervous system. Thanks to these techniques, scientists can link highly specific mental operations — intending to lift your hand, thinking of your mother, hearing music in your head — to precisely located neural activity.

Philosophers, psychologists and neurosurgeons have all weighed in to take charge of these incredible discoveries. Here are some of the things they have told us: the self is “located” in the “mirror neurons”, which fire when people spontaneously imitate the expressions and gestures that they observe. The neurons responsible for intentional activity trigger before we are conscious of “making up our minds”; therefore there is no free will. There is a “God spot” in the brain that is activated by thoughts of the divine, and which is located in a part of the middle frontal gyrus known to be associated with positive emotions, hence the God idea is an adaptation that has promoted our survival in times of trial. Parts of the brain associated with erotic feelings are involved in the appreciation of beauty, and this shows that aesthetic judgment is also an adaptation, arising from the process of sexual selection.

I read this stuff with mounting scepticism, especially now, when the overblown celebrations of Darwin’s anniversary have begun to stick in the throat. I am reminded of the street evangelist who cries “Jesus is the answer”, but who never defines the question. In the same way, we have an accumulation of answers, with no questions asked. Take any aspect of the human condition in which people have invested their hopes and fears — the love of God, of neighbour, of beauty, of virtue — boil it down to a few neurons, and tell the whole story in Darwinese, and you create the impression that some part of the human mystery has been solved. The amazing and puzzling qualities that distinguish us from the rest of nature are merely adaptations, and all are “hard-wired” in the brain.

No doubt there is a part of the brain associated with mathematical calculations. And mathematical competence is an adaptation: if you can’t add, you won’t multiply. Does this tell us what numbers are? Does it solve the great philosophical conundrum of the foundations of arithmetic, or help us to interpret Gödel’s theorem? Of course not. It tells us nothing about mathematics, but only something, and something fairly routine, about the brain. Likewise, the neurononsense that I have summarised tells us nothing about the self, about free will, about God or about beauty. It associates ideas with parts of the brain; but it does not tell us what the ideas mean, or what they refer to. It tells a story about neurons, which cause my arm to rise; but it says nothing about what I do when I raise my arm. And the talk of “adaptations” turns out, on inspection, to be trivial. It tells us that the love of God, of neighbour, of beauty and virtue are not dysfunctional from the point of view of reproduction. Otherwise they would have all died out. Big deal.

The advances in neuroscience have led to a new academic disease, which one might call “neuro-envy”. Old disciplines in the humanities, which relied on critical judgment and cultural immersion, can be given a scientific gloss when rebranded as “neurophilosophy”, “neuroethics”, “neuroaesthetics” and the like. I have come across “neuromusicology”, “neurotheology”, and even “neuroarthistory”, with a whole book on the subject by John Onians. Michael Gazzaniga’s influential study of 2005, The Ethical Brain, has given rise to “law and neuroscience” as an academic discipline, combining legal reasoning and brain imaging, largely to the detriment of our old ideas of responsibility. One by one, real but nonscientific disciplines are being rebranded as infant sciences, even though the only science involved may have little or nothing to do with their subject matter.

In response, I would suggest that aesthetics, criticism, musicology and law are real disciplines, but not sciences. They are not concerned with explaining some aspect of the human condition, but with understanding it, according to its own internal procedures. Rebrand them as branches of neuroscience and you don’t necessarily increase knowledge: in fact, you might lose it. Brain imaging won’t help you to analyse Bach’s Art of Fugue or to interpret King Lear any more than it will unravel the concept of legal responsibility or deliver a proof of Goldbach’s conjecture; it won’t help you to understand the concept of God or to evaluate the proofs for

His existence, nor will it show you why justice is a virtue and cowardice a vice. And it cannot fail to encourage the superstition that says that I am not a whole human being with mental and physical powers, but merely a brain in a box.