2013 Reprint of 1931 edition. Full facsimile of the original edition, not reproduced with Optical Recognition Software. Frank Plumpton Ramsey (1903-1930) was a British mathematician who also made significant and precocious contributions in philosophy and economics before his death at the age of 26. He was a close friend of Ludwig Wittgenstein, and was instrumental in translating Wittgenstein's "Tractatus Logico-Philosophicus" into English, and in persuading Wittgenstein to return to philosophy and to Cambridge. This volume collects Ramsey's most important papers. Contents: The foundations of mathematics.--Mathematical logic.--On a problem of formal logic.--Universals.--Note on the preceding paper.--Facts and propositions.--Truth and probability.--Further considerations.--Last papers.