Bertrand Arthur William Russell (1872–1970) was a British polymath. He considered himself a liberal, a socialist and a pacifist. He is considered one of the founders of analytic philosophy and he is widely held to be one of the 20th century’s premier logicians. His work has had a considerable influence on mathematics, logic, set theory, linguistics, artificial intelligence, cognitive science, computer science (see type theory and type system) and philosophy, especially the philosophy of language, epistemology and metaphysics.