What Is Existentialism?

Different from existential philosophy or existential thinking; philosophical school which allocates a decisive and central position to (man's) existence; tries to understand man, his world and God from this position; philosophy, particularly of Jean-Paul Sartre, emphasizing man's existence — essence presupposes existence — man exists first and constitutes in his situatedness an (the) idea about himself. (Opposite of idealism where existence presupposes essence; the idea of man controls his life.) Sartre's principal philosophical work is L' Etre et le Néant (1945).

Jean-Paul Sartre