Philosopher and mathematician, born in Trelleck, Gwent. He studied at Cambridge, where he became a fellow of Trinity College in 1895. Concerned to defend the objectivity of mathematics, he pointed out a contradictions in Frege's system, published his own Principles of Mathematics (1903), and collaborated with A.N. Whitehead in Principia mathematica (1910-13). In 1907 he offered himself as a Liberal candidate, but was turned down for his 'free-thinking'. In 1916 his pacifism lost him his fellowship, and in 1918 he served six months in prison. From the 1920s he lived by lecturing and journalism, and became increasingly controversial. He visited the Soviet Union, was professor at Peking (1920-1), and with his wife started a progressive school near Petersfield (1927). He succeeded to his brother's title in 1931. The evils of Fascism led him to renounce pacifism in 1939. Later works included An Enquiry into Meaning and Truth (1940) and Human Knowledge (1948). After 1949 he became a champion of nuclear disarmament, and engaged in unprecedented correspondence with several world leaders. One of the most important influences on 20th-c analytic philosophy, he was awarded the Nobel Prize for Literature in 1950, and wrote an Autobiography (1967-69) remarkable for its openness and objectivity.