The Man Who Thought Too Fast

By Anthony Gottlieb is the author of, most recently, “The Dream of Enlightenment.”

In his final year of secondary school, Ramsey decided to focus on pure mathematics, which is what he would earn his degree in, teach, and use as a tool. But philosophy was always what gripped him most. At school, he had read Bertrand Russell’s “The Principles of Mathematics,” which argued for the “logicist” view that mathematical truths and concepts can be derived from logical ones. Much of Ramsey’s early technical work in philosophy built on Russell’s logicist ideas and sorted through their ramifications. For one thing, he improved a theory of Russell’s that had dealt with self-referential paradoxes. (One famous example concerns a barber who shaves all those, and only those, who do not shave themselves. Does he shave himself?)

Ramsey was also an enthusiastic, though not uncritical, admirer of Wittgenstein’s “Tractatus”—a book that Wittgenstein, who first arrived in Cambridge to work with Russell in 1911, completed seven years later, as a soldier in the Austro-Hungarian Army interned in an Italian P.O.W. camp. The “Tractatus” argued that philosophical problems are the result of misunderstanding the logic of language. By revealing its real logic, Wittgenstein believed, he had solved them all. His account of logic enthralled Ramsey, who, in 1921, was recruited to translate the book into English.

A few months after his graduation, in 1923, Ramsey spent a fortnight in Austria, and grilled Wittgenstein about the “Tractatus.” The next year, in March, Ramsey returned and spent six months in Vienna. Wittgenstein’s youngest sister, Gretl Stonborough, took Ramsey under her wing, and he dined every week in her “baroque palace,” with its “vast staircase and innumerable reception rooms,” as he excitedly wrote home. They went to parties and to the opera. Ramsey had not known how immensely rich the family was. (Ludwig lived very simply: he had given all his money to some of his siblings after their father died.) Stonborough’s elder son, Tommy, who was studying mathematics at Cambridge, once said that it seemed as if mathematics were a part of Ramsey’s body, which he used without thinking, like his hands.

Ramsey was eager to discuss philosophy with Wittgenstein, but this time there was another reason for his visit, too. Ramsey wanted to be psychoanalyzed: he was anxious about sex and had been suffering from an “unhappy passion for a married woman,” as he put it in a letter to Wittgenstein. Keynes once observed that Ramsey’s simplicity and directness could be almost alarming. Ramsey, in his journals, noted down an exchange with the woman concerned, who was a close family friend: “Margaret, will you fuck with me?” he asked one day. She replied, “Do you think once would make any difference?” Ramsey seems to have believed that it would, and the matter depressed him, on and off, for two years.

In Vienna, he was treated by Theodor Reik, one of Freud’s first pupils. Initially, Ramsey found the sessions unpleasant and he was sometimes bored by so much talk about himself. He lent Reik a copy of the “Tractatus,” and was annoyed when Reik declared that its author must have some sort of compulsion neurosis. But after six months he told his parents that he found Reik “jolly clever,” and that being analyzed was likely to improve his work. Even the foundations of mathematics could be illuminated by psychoanalysis, Ramsey thought: guarding against one’s emotional biases would make it easier to get a clearer view of the truth. Ramsey returned to Cambridge in October, 1924, and evidently considered himself cured. Meanwhile, Reik told a friend of Ramsey’s that there had never been much wrong with him.

Ramsey, taking up a fellowship at Keynes’s college, King’s, began lecturing on mathematics. Tall and increasingly round, he had a lumbering grace, and acquitted himself well at lawn tennis; a friend, writing in her diary, described a broad face that “always seems ready to break into a wide smile.” He fell in love with Lettice Baker, a spirited woman five years his senior, who had excelled in science and philosophy as a Cambridge undergraduate and was working at the university’s psychology laboratories. They were married in 1925, just after an odd episode during a summer party at Keynes’s country place.

Several Bloomsbury figures were there, including Virginia Woolf and Keynes’s new wife, a Russian ballerina, Lydia Lopokova. Unfortunately, Wittgenstein was, too. Lydia made the mistake of remarking, “What a beautiful tree,” presumably too casually, whereupon Wittgenstein glared and demanded, “What do you mean?” and she burst into tears. Wittgenstein also became annoyed with Ramsey, who took issue when Wittgenstein declared Freud “morally deficient.” Although Ramsey didn’t bear grudges, the two men had no contact for four years, except for a distinctly cool exchange of letters in 1927 about the logic of “=.”

In love and full of ideas, Ramsey said in early 1925, “I find, just now at least, the world a pleasant and exciting place.” This was in a talk he gave to the Apostles, a select and venerable Cambridge discussion club. Ramsey’s main topic that evening was whether there was anything left for such clubs to talk about. The rise of science and the fading of religion meant that the old questions were becoming “either technical or ridiculous,” or so Ramsey argued. He half seriously suggested that conversation, except among experts, was now just a matter of saying how one felt and comparing notes with others. But he ended with a twist. Some might find the world an unpleasant place, yet he had reason on his side—not because any facts supported him but because a sunny attitude did one more good. “It is pleasanter to be thrilled than to be depressed, and not merely pleasanter but better for all one’s activities.”

There was a broader philosophical picture behind his humor. He was attracted by the idea that beliefs of all sorts were best understood in terms of their consequences. He called this “pragmatism,” following the American philosopher C. S. Peirce, who died in 1914. Ramsey took the essence of pragmatism to be that “the meaning of a sentence is to be defined by reference to the actions to which asserting it would lead, or, more vaguely still, by its possible causes and effects. Of this I feel certain.” Part of “the essence of any belief,” he later wrote, is that “we deduce from it, and act on it in a certain way.”

In 1926, Ramsey composed a long paper about truth and probability which looked at the effects of what he called “partial beliefs”—that is, of people’s judgments of probability. This may have been his most influential work. It ingeniously used the bets one would make in hypothetical situations to measure how firmly one believes a proposition and how much one wants something, and thus laid the foundations of what are now known as decision theory and the subjective theory of probability.

Ramsey hoped to turn his essay about truth and probability into a book, which he worked on in the late twenties, but during this time he also produced two articles for The Economic Journal, which was edited by Keynes. One was the article on savings—Ramsey mentioned to Keynes that it was “much easier to concentrate on than philosophy”—and the other was about tax, and ultimately no less consequential. Its key proposal is that, given certain conditions, the rates of sales taxes should be set in such a way that the production of each taxed commodity falls by the same proportion. The tax article, like the savings one, eventually became the basis of a subfield of economics concerned with “optimal taxation,” and changed the way economists thought about public finance.