Ludwig Wittgenstein

Ludwig Wittgenstein was an Austrian-born philosopher, later a British citizen, who worked mainly at Cambridge and is widely counted among the most important philosophers of the twentieth century. He published only one philosophical book in his lifetime, the short Tractatus Logico-Philosophicus (1921), yet he produced two very different philosophies, each of which reshaped the field. The first tried to show how language pictures the world; the second, set out in the posthumous Philosophical Investigations (1953), argued that meaning lies in how words are used in the activities of everyday life.

Wittgenstein was born in Vienna on 26 April 1889, the youngest of eight children of Karl Wittgenstein, a steel magnate and one of the richest men in Austria-Hungary. The family, of Jewish descent but baptised Catholic, was at the centre of Viennese cultural life; Johannes Brahms and Gustav Mahler visited the house, and his brother Paul became a concert pianist. The household was also troubled. Three of his four brothers took their own lives, Hans in 1902, Rudolf in 1904 and Kurt in 1918.

Taught at home until he was fourteen, he attended a technical school in Linz from 1903 to 1906, where Adolf Hitler was briefly a pupil at the same time, though there is no evidence that they knew each other. He then studied mechanical engineering in Berlin and, from 1908, aeronautics at the University of Manchester, where his work on propellers drew him into mathematics and then into the question of what mathematics rests on. Reading the logicians Gottlob Frege and Bertrand Russell, he visited Frege in Jena, who advised him to study with Russell.

In 1911 Wittgenstein arrived at Trinity College, Cambridge. Russell soon decided that his intense, demanding student was a genius who would solve the problems he himself was too old to solve. Wittgenstein worked furiously on logic, and in 1913 withdrew to a hut he built at Skjolden in Norway to think in isolation.

When the First World War began he volunteered for the Austro-Hungarian army. He served on the Eastern Front and later in Italy, asked for the most dangerous posts and was decorated for bravery. Throughout he kept notebooks, which became the Tractatus. He was captured by the Italians in November 1918 and spent months in a prisoner-of-war camp near Monte Cassino, from where he sent the manuscript to Russell.

The Tractatus Logico-Philosophicus is a book of numbered remarks, under eighty pages long. It argues that the world is the totality of facts, and that a meaningful sentence is a logical picture of a possible fact: its parts stand for things, and their arrangement shows how the things are arranged. The truths of logic say nothing about the world at all; they are tautologies, true whatever the facts. From this it follows that much of what philosophers try to say cannot be said. Claims about ethics, aesthetics, the meaning of life and even the book's own account of language lie outside the limits of sense. They can at best be shown. The book ends with its most famous line: what we cannot speak about we must pass over in silence.

The book appeared in German in 1921 and in English in 1922, with an introduction by Russell that Wittgenstein felt misunderstood it. It deeply impressed the Vienna Circle of logical positivists, who read it as support for their view that only scientifically verifiable statements have meaning, although Wittgenstein himself put far more weight on what lay beyond what can be said.

Believing he had solved the problems of philosophy, Wittgenstein gave away his share of the family fortune to his siblings and trained as a schoolteacher. From 1920 to 1926 he taught children in villages of Lower Austria, including Trattenbach and Otterthal. He was strict and sometimes violent, and in 1926 he left teaching after a boy he had struck collapsed, an episode known as the Haidbauer incident. He then worked as a gardener at a monastery and spent two years designing a severe modernist house in Vienna for his sister Margarethe Stonborough. Meetings with members of the Vienna Circle, and a lecture by the mathematician L. E. J. Brouwer in 1928, revived his interest in philosophy.

In 1929 he returned to Cambridge, received a doctorate for the Tractatus, with Russell and G. E. Moore as examiners, and began teaching. His lectures, given without notes, were less talks than live struggles with problems in front of a small group of students. He became professor of philosophy in 1939, succeeding Moore. After Nazi Germany annexed Austria in 1938 his family was classed as Jewish under the race laws, and he took British citizenship. During the Second World War he worked as a porter at Guy's Hospital in London and as a laboratory assistant in Newcastle. He resigned his chair in 1947 and spent long periods in Ireland, in Dublin and on the coast of Connemara.

His later thought rejected central ideas of the Tractatus. Language, he now argued, has no single hidden logical essence. Words are used in countless "language games", such as giving orders, telling jokes, describing objects or praying, each embedded in a shared form of life, and the meaning of a word is largely its use. Many words have no common definition but a network of overlapping similarities, which he called family resemblances: there is no one feature shared by all games. His remarks on following a rule and on the impossibility of a purely private language challenged the picture, inherited from Descartes, of the mind as an inner theatre known only to its owner. Philosophical problems, on this view, arise when language "goes on holiday", and the task of philosophy is to untangle such confusions rather than to build theories.

Wittgenstein died of prostate cancer in Cambridge on 29 April 1951, at the house of his doctor. His reported last words were a message for his friends: tell them I have had a wonderful life.

Almost all of Wittgenstein's later work was published after his death from his notebooks and typescripts, beginning with Philosophical Investigations in 1953 and followed by The Blue and Brown Books, Remarks on the Foundations of Mathematics, Zettel and On Certainty, a late study of doubt and knowledge. His early work shaped logical positivism; his later work inspired ordinary language philosophy at Oxford and is still central to the philosophy of mind, language and mathematics. Among his influences he named Frege and Russell, and earlier reading of Schopenhauer, Tolstoy and Kierkegaard left a mark on his ethical and religious outlook. His austere life, uncompromising character and oracular style have made him a figure of fascination well beyond analytic philosophy, the tradition he did so much to shape and then to unsettle.