Martin Heidegger

Heidegger was the son of the sexton of the Catholic church in Messkirch, a small town on the edge of the Black Forest. Church scholarships took him through school and university; he intended the priesthood, gave it up for reasons of health, turned to philosophy, took his doctorate in 1913 and his teaching qualification in 1915 with a thesis on Duns Scotus. In the war he served in a meteorological unit. In 1919 he broke with Catholicism, became Husserl's assistant and lectured at Freiburg, where students said his classes cast a spell like a magician's.

In 1923 he became professor at Marburg; his students included Gadamer, Löwith, Arendt (with whom he had a secret affair) and future theologians. Being and Time appeared in 1927, only the first half of the planned work, and changed German philosophy at once. Western philosophy since Plato, it argues, has forgotten Being itself and studied only beings; to raise the question again one must first analyse the being that can ask it, the human being, which he calls Dasein. The being of Dasein is care; its structure is being-in-the-world; it is thrown into a world already meaningful, falls into the idle talk of 'the they', and can exist authentically only in anxiety and in facing its own death. Temporality is the meaning of Dasein's being.

In 1928 he succeeded Husserl at Freiburg. In April 1933 he became rector of the university and in May joined the Nazi party; his inaugural address summoned the university to serve the nation's 'historical mission'. He resigned after a year but kept his party membership until 1945. After the war the French occupation authorities banned him from teaching for five years. He never publicly apologised; a Spiegel interview of 1966, published after his death, offers more excuse than reflection. The Black Notebooks, published from 2014, show antisemitic content in his thinking of the 1930s. The relation between his philosophy and his politics is still argued over.

From the 1930s his thought underwent a 'turn': no longer starting from Dasein but from the history of Being itself, which reveals and conceals itself differently in each epoch; metaphysics is the history of the forgetting of Being, and Nietzsche its end. He turned to Hölderlin's poetry, the Presocratic fragments, language ('the house of Being') and technology, which turns everything into 'standing-reserve' available for control, the supreme danger. He wrote in a hut in the Black Forest and said late in life that 'only a god can save us'. His influence reaches Sartre, Merleau-Ponty, Gadamer, Levinas, Derrida and Foucault, and extends into theology, architecture and ecological thought.