German philosopher Martin Heidegger (1889-1976) has become widely regarded as the most original 20th century philosopher. Recent interpretations of his philosophy closely associate him with existentialism (despite his repudiation of such interpretations) and, controversially, with National Socialist (Nazi) politics.

Martin Heidegger was born in Messkirch, a small town in Baden in southwest Germany, on Sept. 26, 1889. His father was a verger in the local Catholic church, and the boy received a pious upbringing. After graduation from the local gymnasium, he entered the Jesuit novitiate; later, he studied Catholic theology at the University of Freiburg. The markedly philosophical cast of medieval theology helped attract Heidegger to philosophy, and he finished his education in that subject. In 1914 he presented a doctoral thesis entitled "The Theory of Judgment in Psychologism," which showed the strong influence of Edmund Husserl's writings. A year later he was admitted to the faculty of Freiburg as a...