This paper examines the challenge that psychoanalytic theory cannot be refuted. It does so by considering the theory in its orthodox Freudian form, and in the main branches into which it can be divided ? the theory of Instincts, of Development, of Psychic Structure, of Mental Economics or Defence, and of Symptom Formation. The essential character of the generalizations and concepts of these branches will just be indicated; and we shall ask of each branch whether it is possible to refute (...) it. A considerable amount of scientific enquiry has been done into the concepts and generalizations of psychoanalysis. Relevant examples of these enquiries will be noted; and the question asked whether these scientific studies have in fact done anything to refute or support the various branches of psychoanalytic theory. The general upshot will be that the challenge is both important and a mistake. (shrink)