Freud's definition of the relationship between hypnosis and psychoanalysis is a political one that even then pointed to the paradigmatical sciences as defined by Kuhn. Nevertheless, the historian who applies to psychoanalysis the technique of symetry elaborated for such sciences, runs up against a set of singularities that risk bringing him to a position of denouncer of a "fake science". We emphasize that, if the historian does not limit himself to the positivist position or to the history of ideas, he will inevitably find himself engaged in the history that he is analyzing, but with the responsibility of his mode of engagement. We propose to define hypnosis and psychoanalysis as fields inhabited by the question of science in the modern sense of the term, and raising the issue of pertinence, as far as they are concerned, of the theoretical experimental model that guided them.