In an effort to study the mechanism whereby psychoanalytic propositions are changed, we have traced the history of the origins and evolution of three early working hypotheses. These are the hypnoid hypothesis, the seduction hypothesis, and the concept of the actual neurosis. Certain generalizations emerged from the detailed examination of the process by which Freud altered these concepts during the course of his long scientific career.

1Freud attempted successfully to increase the generalizability of his hypotheses as new data were acquired. Thus, the seduction hypothesis evolved into the oedipus complex and a complex of observations and concepts around the idea of infantile sexuality; the concept of the actual neuroses became a metapsychologically subordinate aspect of the second anxiety theory; and the hypnoid hypothesis was dropped in favor of a much broader conflict-defense theory of psychoneurosis. The original statement of the hypothesis frequently was seen as a special case of the new, more broadly based hypothesis.