Existentialism, for some of its severe critics, represents a temporary outburst of the dark side of man which is indicative of a passing phenomenon of our age and particularly of the postwar angry generation living on the morbid edges of death, anxiety and the absurdity of human existence. They contend that existentialism is not a philosophy or at least not a serious and disciplined philosophy. Professor Henry S. Kariel characterized existential psychology as “negativism,” and its counterpart, behavioral psychology, as “positivism”; and similarly Professor Eugene J. Meehan describes the phenomenology of Edmund Husserl as having sought to find philosophical certainty “in feeling rather than in thought,” an assessment that falsely indicts phenomenology as an irrationalism. I have singled out these two political theorists as representatives of a widespread misconception of existential philosophy and phenomenology, held as well, I suspect, by many American political theorists. This article is not designed as a direct rebuttal to these misunderstandings and criticisms; it is rather an attempt to show what I consider to be the significant and positive contributions of existential philosophy and phenomenology to the foundation of political theory.