Cambridge mathematician and philosopher. Ramsey made important contributions to mathematical logic, probability theory, the philosophy of science (see Ramsey sentence), and economics. He showed how the distinction between the semantic paradoxes, such as that of the Liar, and Russell's paradox, made unnecessary the ramified type theory of Principia Mathematica, and the resulting axiom of reducibility. Much of Ramsey's work was directed at saving classical mathematics from intuitionism, or what he called the ‘Bolshevik menace of Brouwer and Weyl’. In the theory of probability he was the first to show how a personalist theory could be developed, based on precise behavioural notions of preference and expectation. In the philosophy of language, Ramsey was one of the first thinkers to accept a redundancy theory of truth, which he combined with radical views of the function of many kinds of proposition. Neither generalizations, nor causal propositions, nor those treating probability or ethics, describe facts, but each has a different specific function in our intellectual economy. Ramsey was one of the earliest commentators on the early work of Wittgenstein, and his continuing friendship with the latter led to Wittgenstein's return to Cambridge and to philosophy in 1929.