A 20th-century movement in philosophy. Although it grew out of the development of the philosophical tradition all over Europe, it was highly popularized in France in the 1940s and is usually associated with the theories expressed by Jean - Paul Sartre. The beginnings of existentialism are found in the writings of the Danish Sooren Kierkegaard, the German Friedrich Nietzsche, and the Russian Fyodor Dostoyevsky, although none of them formulated a logical system. The works of the Germans Martin Heidegger and Karl Jaspers were the most immediate influence on Sartre's thinking, along with the method of approach of the phenomenologist Edmund Husserl.
All existentialists are concerned with ontology, the study of being. The point of departure is human consciousness and mental processes. In contrast to most previous philosophical systems, which maintain that an a priori essence precedes or transcends the individual existence of people or of objects, the existentialists conclude that existence precedes essence. The significance of this for human beings is that the concept that a man has an essential self is shown to be an illusion. A man's self is nothing except what he has become; at any given moment, it is the sum of the life he has shaped until then. The " nothing " he begins with is thus the source of man 's freedom, for at each moment it is man's will that can choose how to act or not to act. However, each such decision affects the future doubly: a man is or should be responsible for the consequences of his actions; and each action necessarily excludes the other potential actions for that moment, and their consequences, and thus at least partially limits the potentialities for future actions.
By what standards, then, should man make his decisions? Man 's mind cannot discern any meaning for this existence in the universe; when he abandons his illusions, he finds himself horrified by the absurdity of the human condition. The question of the existence of God (or some cosmic purpose) is irrelevant, according to Sartre and the atheistic existentialists, because even if He does exist (which they usually deny), He does not reveal to men the meaning of their lives. Thus man must create a human morality in the absence of any known predetermined absolute values. Honesty with oneself is perhaps the major value common to existentialist thinking; all their writings describe the emotional anguish of trying to achieve it. Sartre calls the "man of good faith" one who understands the human condition described above and fully accepts the responsibility of the freedom it entails. The "man of bad faith" accepts illusion, is deliberately hypocritical, or tries to use the excuse of "good intentions" to escape responsibility for the consequences of his actions, the ramifications of which always involve other people. The man of good faith judges a potential action by estimating the result if everyone, not just himself, were to perform it. Yet despite the difficulty of choice, he does not withdraw from life, but is engage, actively engaged in the business of living with himself and with other men.
The Christian existentialists agree that man can never know God 's purpose, but they affirm that it exists and that through a "leap of faith" man can establish his values in accordance with it. However, they too describe the anguish and the responsibility of honest action, for a man can never be certain that his decision is actually based on an intuition of the divine and not on the disguised temptation of evil.
Other writers in the existentialist tradition are Gabriel Marcel, leader of Christian existentialism in France, the Spaniards Miguel de Unamuno and Jose Ortega y Gassei, and the Jewish mystic Martin Buber.
Albert Camus is often classified with the movement, but he considers many of Sartre's postulates as much an unjustifiable "leap of faith" as that of the religious existentialists. His "man of the absurd" resembles Sartre's "man of good faith" in that both acknowledge man's lonely condition in the face of the silence of the universe; both reject despair and commit themselves to the anguish and responsibility of living as best one can; and both consider the exercise of one's own freedom inseparable from the opportunity for all men to exercise theirs, which is contingent on their freedom from poverty, political oppression, and other avoidable external limitations. However, Camus's writings do not attempt to constitute an organized philosophical system of ontology, as do Sartre's.