Abstract
In this paper I propose to say something about why certain key psychoanalytic concepts, particularly that of the unconscious, are special because of a studied, and therapeutically important, ambiguity or paradoxicality which affects them. Before I examine these concepts, however, the first section of this paper discusses some of Sartre's views on psychological explanation. On the one hand, this gives me a way of introducing the dichotomy of self-evident irreducibility and existential lucidity which underlies my account of the unconscious. On the other hand, it is important because I take Sartre to be addressing, less successfully, the very same question that Freud dealt with by introducing his ambiguous concepts.