There is always a certain hour of the day and of the night when a man’s courage is at its lowest ebb, and it was that hour only that he feared.

Soon after the event on 6 August 1945 he was one of the few French editors to publicly express opposition and disgust to the United States' dropping the atomic bomb in Hiroshima. His views contributed to the rise of the philosophy known as absurdism. To distinguish his ideas scholars sometimes refer to the Paradox of the Absurd when referring to "Camus's Absurd".

In an interview in 1945 Camus rejected any ideological associations: "No I am not an existentialist. Sartre and I are always surprised to see our names linked. In 1949 Camus founded the Group for International Liaisons within the Revolutionary Union Movement after his split with Garry Davis's Citizens of the World movement of which the surrealist André Breton was also a member.