Bertrand Russell

Bertrand Russell was a British philosopher, logician and campaigner whose long life ran from the age of Gladstone to the Vietnam War. With Gottlob Frege, G. E. Moore and his own student Ludwig Wittgenstein, he founded analytic philosophy, the tradition that treats logic and the careful analysis of language as the main tools of philosophy. He was also one of the best-known public intellectuals of the twentieth century, imprisoned twice for his protests, and in 1950 he received the Nobel Prize in Literature.

Russell was born on 18 May 1872 at Ravenscroft, a country house at Trellech in Monmouthshire, Wales, into one of the great Whig families of the United Kingdom. His grandfather, Lord John Russell, had twice been prime minister. His parents, Viscount and Viscountess Amberley, were radicals who supported birth control and women's suffrage, and they chose the philosopher John Stuart Mill as his secular godfather. Both parents had died by the time he was four, and he was brought up by his grandmother at Pembroke Lodge in Richmond Park, a strict, religious but politically liberal household.

Educated at home by tutors, he was a lonely child. He later wrote that discovering Euclid at the age of eleven was one of the great events of his life, and that his wish to know more mathematics kept him from despair. In 1890 he went to Trinity College, Cambridge, where he studied mathematics and then philosophy, and where he became friends with Moore and the mathematician Alfred North Whitehead. In 1894 he married Alys Pearsall Smith, an American Quaker; it was the first of four marriages.

At Cambridge, Russell first followed the British idealists, who drew on Hegel and held that reality is a single spiritual whole. Around 1898 he and Moore rebelled against this view, insisting that the world contains many independent things and that relations between them are real. A book on Leibniz in 1900 and a meeting with the Italian logician Giuseppe Peano that year turned him towards the project that defined his early career: showing that mathematics could be derived from pure logic, a programme known as logicism.

In 1901 he found a contradiction at the heart of the new logic. Consider the set of all sets that are not members of themselves: if it is a member of itself, it is not, and if it is not, it is. This puzzle, Russell's paradox, showed that the system of Gottlob Frege, on which Russell had been building, was inconsistent, and he told Frege so in a famous letter of 1902. Russell's answer was the theory of types, which arranges sets in levels so that no set can contain itself. The Principles of Mathematics (1903) set out the programme, and Principia Mathematica, written with Whitehead and published in three volumes between 1910 and 1913, attempted to carry it through in full. The work was a landmark of modern logic, though later results, above all Kurt Gödel's incompleteness theorems of 1931, showed that no such system could capture all mathematical truth.

Russell's 1905 article "On Denoting" became a model of analytic philosophy. It addressed sentences such as "the present King of France is bald", which seem to be about something that does not exist. Russell argued that the grammar misleads us: the sentence really says that there is exactly one present King of France and that he is bald, so it is simply false. The theory of descriptions showed how logical analysis could dissolve problems created by the surface form of language.

He applied the same method to knowledge. He distinguished knowledge by acquaintance, direct awareness of things such as sense data, from knowledge by description, and tried to show how our knowledge of the outer world could be built up from what we directly experience. The Problems of Philosophy (1912), a short introduction still widely read, presented these ideas to general readers. In lectures of 1918 he called his position logical atomism: the world consists of simple facts, and a perfect logical language would mirror their structure. From 1911 he worked closely with the young Austrian Ludwig Wittgenstein, whose criticisms shook his confidence and whose Tractatus Logico-Philosophicus he helped bring into print in 1922.

When the First World War broke out, Russell opposed it publicly. He was fined in 1916 for a leaflet defending a conscientious objector and lost his lectureship at Trinity. In 1918 he was sentenced to six months in Brixton prison for an article suggesting that American troops might be used to break strikes in Britain; in his cell he wrote Introduction to Mathematical Philosophy. In 1920 he visited Soviet Russia, met Lenin, and came home a critic of Bolshevism, then spent most of a year lecturing in China.

Without an academic post, he lived by writing and lecturing. With his second wife, Dora Black, he founded the experimental Beacon Hill School in 1927. Books such as Marriage and Morals (1929), which questioned conventional sexual morality, and his essays against Christianity made him notorious. In 1931 he inherited the family title as the third Earl Russell. In 1940 a court in New York blocked his appointment to the City College there on the grounds of his moral views. During the 1930s he favoured appeasement, but by the Second World War he had concluded that Nazi Germany had to be resisted by force. His History of Western Philosophy (1945), lively and opinionated, brought him financial security for the first time.

After 1945 Russell became a leading voice against nuclear weapons. At first he argued that the West might need to threaten the Soviet Union while the United States alone had the bomb, but as the Cold War arms race grew he turned to disarmament. In 1955 he issued the Russell–Einstein Manifesto with Albert Einstein and other scientists, warning of the danger of nuclear war; it led to the Pugwash conferences. He became the first president of the Campaign for Nuclear Disarmament in 1958, then left it for the more militant Committee of 100, and in 1961, aged 89, was jailed for a week after a sit-down protest. In the 1960s he denounced American involvement in the Vietnam War and, with Jean-Paul Sartre, organised the unofficial International War Crimes Tribunal of 1966–1967.

He died at his home, Plas Penrhyn, near Penrhyndeudraeth in north Wales, on 2 February 1970, aged 97.

Russell's lasting importance lies first in logic and the philosophy of mathematics, where Principia Mathematica shaped the work of Gödel, Alan Turing and the founders of computer science. His theory of descriptions and his insistence on clear, piecemeal argument set the pattern for analytic philosophy, which became the dominant style in the English-speaking world. His later philosophical work received less respect than his early logic, and many critics found his popular history of philosophy unfair to thinkers he disliked. Yet his gift for plain, witty English, his more than seventy books and his readiness to go to prison for his beliefs made him, for many people, the model of what a philosopher engaged with public life could be.