Bertrand Arthur William Russell, 3rd Earl Russell, OM, FRS (18 May 1872 – 2 February 1970) was a British philosopher, logician, mathematician, historian, and social critic. At various points in his life he imagined himself a liberal, a socialist, and a pacifist, but he also admitted that he had never been any of these things in any profound sense. He was born in Wales, into one of the most prominent aristocratic families in Britain.
Russell led the British "revolt against idealism" in the early 1900s. He is considered one of the founders of analytic philosophy along with his predecessor Gottlob Frege and his protégé Ludwig Wittgenstein, and is widely held to be one of the 20th century's premier logicians. He co-authored, with A. N. Whitehead, Principia Mathematica, an attempt to ground mathematics on logic. His philosophical essay "On Denoting" has been considered a "paradigm of philosophy." His work has had a considerable influence on logic, mathematics, set theory, linguistics, computer science (see type theory and type system), and philosophy, especially philosophy of language, epistemology, and metaphysics.
Russell was a prominent anti-war activist; he championed free trade and anti-imperialism. Russell went to prison for his pacifism during World War I. Later, he campaigned against Adolf Hitler, then criticised Stalinist totalitarianism, attacked the United States of America's involvement in the Vietnam War, and was an outspoken proponent of nuclear disarmament. One of his last acts was to issue a statement which condemned Israeli aggression in the Middle East.