Abstract
Roderick Firth (1917–87) received his BA from Haverford in 1938 and his PhD from Harvard in 1943. He taught at William and Mary from 1943 to 1945 and at Swarthmore between 1945 and 1953. From 1953 until 1987 he taught at Harvard, where he became Alford Professor in 1962. Most of Firth's writings are in epistemology; he defended a version of radical (Berkeleyan/phenomenalist) empiricism. His reputation in ethics rests almost entirely on his paper “Ethical Absolutism and the Ideal Observer,” which gives the classic statement of the ideal observer theory.