Bertrand Russell, who was the grandson of an English prime minister, and who was raised by his grandparents because his parents died when he was young, published his first books in the 19th Century, but became famous with the discovery of the paradox named after him, and with the writing of Principia Mathematica, published 1910-1912, which he did together with Alfred North Whitehead.

The Principia Mathematica aimed at deriving mathematics from logic, and may be said to have failed in that respect, since it contains axioms that cannot be fairly regarded as axioms of logic (notably: the axioms of infinity and choice, and the theory of types). Even so, it was hugely influential as one of the founding works of mathematical logic.

Russell was removed from his teaching post at Cambridge University during the First World War, because he opposed that war. After that, he lived from his own pen.

He was also an important influence in analytic philosophy, which he may be said to have founded together with G.E. Moore. Russell wrote many books related to philosophy, and was most of his life a democratic socialist, who opposed Soviet communism and dictatorships, and who favoured enlightened education and freer sexual morals.

In the last 25 years of his life he opposed the proliferation of atomic weapons. He received the Nobel Prize for Literature in 1950. This was at least in part because of his 'History of Western Philosophy', which is a good and highly readable introduction to the subject (and indeed the only one that made me laugh).

There are many biographies of Russell, including his own 'Autobiography' in three volumes, and including a 'Political Life' of him by Alan Ryan. Russell was somewhat of a hero of what may be fairly called 'the thinking left' in the 20th Century - those with an interest in scientific reasoning and some sympathy for socialist and liberal ideas and ideals - and this colored many biographies. A recent and large biography of Russell in two volumes is by Ray Monk, and is a good antidote for those inclined to hero-worship Russell: He was highly intelligent and an important philosopher, but not quite the man he himself depicted and wanted to be.