As a philosopher of mind, Edwin P has two readings of his own psychology that, though elegantly intertwined, provide different explanations of the way he has come to think and live. The first traces a narrative of traumatic events in his African upbringing, and his repudiation of a British colonial mind-set.

Born in 1947 in Malawi, Edwin grew up mostly in the company of servants, saw his parents rarely and, aged 13, was sent to an elite public school in Rhodesia - a country he refers to reflexively as Zimbabwe, as if its previous identity had been imaginary. He describes his teenage self as clever, cocky and sexually prolific: traits that functioned, in part, as survival strategies among the Edwardian-style brutalities of a school where he was flogged so savagely that, one night, he fled into the African bush after his pyjama trousers became glued to the bloodied welts on his buttocks. He suffered nightmares for years afterwards.

If school was grotesque, the occasional experience of family life was like being caught "between the Wehrmacht and the Bolshevik army in a domestic Stalingrad". His older sister had been born in a botched high-forceps delivery that damaged her skull and left her with a severe motor tremor. Otherwise mentally normal, Julia's spasmodic movements shamed her into isolation and threw her into conflict with their neurotic and angry mother, who tried to drive her daughter out of withdrawal amid "screaming, shouting and the slamming of doors".

Julia's death was triggered, with grim irony, by a cure. In 1963, a brain operation removed her tremors and, having never before hoped for male attention, she made up for lost time - with catastrophic results. One relationship ended with a suicide attempt, another when she got married. Within weeks of the wedding, her corpse was pulled out of a river in South Africa, horribly disfigured. There were seven knife wounds in her chest. Her husband was tried but acquitted. Her mother, who suffered from a heart condition, had collapsed shortly after identifying the body. The two women were dead within a month of one another.

At Cambridge, aged 18, shocked into numbness, Edwin began to suffer panic attacks and to drink himself to sleep. During one alcoholic fug, he got a girl pregnant, married her and, for a while, the prospect of becoming a father seemed like "a sort of restitution", as if his family were being remade. But the marriage was a disaster and he was thrown back on to what he calls his rationally justified anxieties. This was, however, the making of him. "When things happen traumatically, it can sharpen the focus on how you deal with them," he says, "and what it is you value."

Seeking marriage guidance, Edwin was instead offered an early form of cognitive therapy, which provided him with a structured psychological routine for managing his attacks. And these turned out to be practical illustrations of the deeper foundations of rational thought he was investigating as a philosopher. "Confronted with grief or disaster, I think reason is extremely ineffectual in the short term," he says. "But in the medium to long term, it can be an adaptive tool, an orientation, a way of facing things that helps you in your reactions to events."

Edwin still can't stand food that reminds him too vividly of his African childhood, and he maintains a grip on his interior life with a furiously workaholic routine. While still teaching full time at Yale, he publishes an academic paper every month in a journal somewhere in the world, while writing newspaper articles under a variety of pseudonyms. Every year, for an American philosophical publisher, he writes the biography of a great philosopher, in which the life and the ideas are always viewed as entirely separate entities.

In an unguarded moment, he remarks that his drive to work is a product of panic. Then he reflects, and adapts his response: "Panic isn't right. My reaction to disaster was to make a decision to work; a rational choice superimposed itself."

Yet, when it comes to the drives of his personality, he doesn't think of the traumas of adolescence and adulthood. His second explanation of himself - the donkey's tail of causality - gets pinned on "the inner life", one that seemed to be there from the moment he picked up a pencil. The isolation of his African childhood created a reinforcing environment, but the urge to know feels as if it prefigured memory. Aged 13, before the beatings began, he had picked up Descartes' Meditations and was introduced to the idea that there should somehow be a division between mind and brain. "My God," he remembers thinking, "I can understand this. This is it. This is what I'm going to do."

· Names and details have been changed