Charlie Dunbar Broad (30 December 1887 – 11 March 1971), usually cited as C. D. Broad, was an English epistemologist, historian of philosophy, philosopher of science, moral philosopher, and writer on the philosophical aspects of psychical research. He was known for his thorough and dispassionate examinations of arguments in such works as Scientific Thought (1923), The Mind and Its Place in Nature (1925), and Examination of McTaggart's Philosophy (2 vols., 1933–1938). Broad's essay on "Determinism, Indeterminism, and Libertarianism" in Ethics and the History of Philosophy (1952) introduced the philosophical terms occurrent causation and non-occurrent causation, which became the basis for the contemporary distinction between "agent-causal" and "event-causal" in debates on libertarian free will. Biography Broad was born in Harlesden, in Middlesex, England. He was educated at Dulwich College from 1900 until 1906. He gained a scholarship in 1906 to study at Trinity College, Cambridge, graduating in 1910 with First-Class Honours, with distinction. He became a Fellow of Trinity College the following year. Career As his fellowship at Trinity College was a non-residential position, he was also able to accept a position as an assistant lecturer that he had applied for at St Andrews University, where he remained until 1920. That year, he was appointed professor at Bristol University, working there until 1923, when he returned to Trinity as a lecturer. From 1926 until 1931, he was a lecturer in 'moral science' at Cambridge University's Faculty of Philosophy. Later at Cambridge, he was appointed in 1931 as 'Sidgwick Lecturer', a role he would keep until 1933, when he was appointed Knightbridge Professor of Moral Philosophy at the University, a position he held for twenty years (until 1953). In 1927 he gave the British Academy's Master-Mind Lecture, entitled Sir Isaac Newton. In addition, Broad was President of the Aristotelian Society from 1927 to 1928, and again from 1954 to 1955. He was also President of the Society for Psychical Research in 1935 and 1958. Personal life Broad was openly homosexual at a time when homosexual acts were illegal. In March 1958, Broad along with fellow philosophers A.J. Ayer and Bertrand Russell, writer J.B. Priestley and 27 others sent a letter to The Times which urged the acceptance of the Wolfenden Report's recommendation that homosexual acts should "no longer be a criminal offence." Theory Psychical research Broad argued that if research could demonstrate that psychic events occur, this would challenge philosophical theories of