Bertrand Arthur William Russell (1872-1970) was a philosopher, mathematician, and social advocate whose views made him an influential and controversial figure. Born in Wales to an aristocratic family, Russell developed a precocious talent for mathematics, which he came to see as the pathway to absolute certainty in intellectual knowledge. He studied this subject at Trinity College, Cambridge, then switched to philosophy, to which he brought a mathematical approach.

Originally a follower of German Idealism, Russell’s interest in mathematics and science led him to eventually embrace logical positivism—the decidedly analytical, rationalistic, and scientistic branch of modern philosophy which he advocates at the close of A History of Western Philosophy. Russell also increasingly took an interest in sociopolitical issues: His pacifist views and opposition to Britain’s involvement in World War I led to his imprisonment for six months, during which time he wrote his Introduction to Mathematical Philosophy.

Between the two world wars, Russell and his second wife, Dora, became known for promoting the ideas of socialism, the defiance of conventional sexual morality, and progressivist educational reform. These views, along with his frank atheism, led to the cancelation of Russell’s appointment to teach at the City College of New York in the early 1940s.