Born of a Swiss father and Belgian mother, Ayer was educated in Britain. After graduating from Oxford in 1932 he studied in Vienna for a year, before returning to teach at Oxford. His exposure to the logical positivists produced the scintillating and iconoclastic Language, Truth, and Logic (1936), which introduced positivism to the wider English-speaking public. It was followed by the Foundations of Empirical Knowledge in 1940. After the Second World War Ayer held chairs at University College London, from 1946, and at Oxford from 1959. The Problem of Knowledge (1956) has been an influential introduction to that topic. In later years Ayer turned increasingly to the history of philosophy, producing volumes on Moore and Russell, pragmatism, Hume, and Voltaire. His philosophy was infused with the empiricism of Hume and the logic of Russell, and inherited both the strengths and weaknesses of those thinkers. Ayer also played a prominent intellectual role in British political life, writing for a wider public and espousing a variety of liberal causes with notable flair and wit. The definitive biography is by Ben Rogers (2002).