Ludwig Wittgenstein moves to Cambridge to study philosophy under Bertrand Russell

Alfred North Whitehead and Bertrand Russell complete a work of mathematical logic, Principia Mathematica

Ludwig Wittgenstein publishes his influential study of the philosophy of logic, Tractatus Logico Philosophicus

In I and Thou the Austrian theologian Martin Buber interprets religion in terms of the subjective experience of interpersonal relationships

In Being and Time German philosopher Martin Heidegger makes an existentialist case with Dasein ('Being There') as the central theme

In Language, Truth and Logic 26-year-old A.J. Ayer produces a classic exposition of Logical Positivism

French philosopher Jean-Paul Sartre expounds his theory of existentialism in Being and Nothingness ('L'Être et le néant')

Austrian philosopher Karl Popper publishes The Open Society and its Enemies