Presenting a paper on existentialism is somewhat like escorting a lady of rather dubious reputation to a party: the half-smiles and half-concealed glances are matched by an absorbing interest in the newcomer, and there is a nervousness in the discussion. Among philosophers the term "existentialism" is unique in this respect: no other term can make philosophers smile. What they are smiling about remains a mystery; that they smile, however, is no less mysterious. Again, there is a nervousness which teases about the subject, and which, in the end, is often all that ever emerges from the discussion. But even where existential philosophy is given a more serious hearing, the sense of mystery never quite vanishes; it transposes itself instead into an almost eschatological expectancy, the awaiting of a resolute answer to the jocular yet desperate question, "Well, what exactly is existentialism ?" Unfortunately, most goodwilled and competent efforts to answer this question are blocked at the outset by misunderstandings, mistaken preconceptions on the part of the questioner. Moreover, the questioner too often falls into one of several patterns. Perhaps the best way of introducing my conception of existential philosophy is by indicating, briefly, some of the typical objections raised against it and then proceeding to a positive statement of what I take to be the "real thing."