Jean-Paul Sartre Signed Photograph.

French philosopher, novelist, playwright, political activist, and literary critic Jean-Paul Sartre was one of the key figures in the philosophy of existentialism and phenomenology, and one of the leading figures in 20th-century French philosophy and Marxism. The conflict between oppressive, spiritually destructive conformity (mauvaise foi, literally, 'bad faith') and an "authentic" way of "being" became the dominant theme of Sartre's early work, a theme embodied in his principal philosophical work Being and Nothingness (L'Être et le Néant, 1943). Sartre was awarded the 1964 Nobel Prize in Literature despite attempting to refuse it, saying that he always declined official honors and that "a writer should not allow himself to be turned into an institution."