Sir Alfred Jules "Freddie" Ayer ( ; 29 October 1910 – 27 June 1989), usually cited as A. J. Ayer, was an English philosopher known for his promotion of logical positivism, particularly in his books Language, Truth, and Logic (1936) and The Problem of Knowledge (1956). Ayer was educated at Eton College and the University of Oxford, after which he studied the philosophy of logical positivism at the University of Vienna. From 1933 to 1940 he lectured on philosophy at Christ Church, Oxford. During the Second World War Ayer was a Special Operations Executive and MI6 agent. Ayer was Grote Professor of the Philosophy of Mind and Logic at University College London from 1946 until 1959, after which he returned to Oxford to become Wykeham Professor of Logic at New College. He was president of the Aristotelian Society from 1951 to 1952 and knighted in 1970. He was known for his advocacy of humanism, and was the second president of the British Humanist Association (now known as Humanists UK). Ayer was president of the Homosexual Law Reform Society for a time; he remarked, "as a notorious heterosexual I could never be accused of feathering my own nest." Life Ayer was born in St John's Wood, in north west London, to Jules Louis Cyprien Ayer and Reine (née Citroen), wealthy parents from continental Europe. His mother was from the Dutch-Jewish family that founded the Citroën car company in France; his father was a Swiss Calvinist financier who worked for the Rothschild family, including for their bank and as secretary to Alfred Rothschild. Ayer was educated at Ascham St Vincent's School, a former boarding preparatory school for boys in the seaside town of Eastbourne in Sussex, where he started boarding at the relatively early age of seven for reasons to do with the First World War, and at Eton College, where he was a King's Scholar. At Eton Ayer first became known for his characteristic bravado and precocity. Though primarily interested in his intellectual pursuits, he was very keen on sports, particularly rugby, and reputedly played the Eton Wall Game very well. In the final examinations at Eton, Ayer came second in his year, and first in classics. In his final year, as a member of Eton's senior council, he unsuccessfully campaigned for the abolition of corporal punishment at the school. He won a classics scholarship to Christ Church, Oxford. He graduated