This paper describes post-positivist epistemological assumptions and their development since the 1950s. As a vehicle for organizing the discussion, two recent articles in American Psychologist (Manicas & Secord, 1983, and Gergen, 1985) are reviewed and compared. Both articles have a similar purpose–to describe post-positivist psychology - but they differ in terms of how social reality is conceptualized. This dif - ference points to an open issue in theoretical psychology and to the role of epistemic beliefs in the world views that psychologists accept or reject. In order to emphasize the need for more attention to the psychological development of epistemic beliefs (and of psychological theorizing itself), the historical evolution of post-positivist assumptions in psychology is viewed through the lens of Perry's (1970) theory of intellectual development. The structural similarities between individual intellectual development and the evolution of formal epistemology suggest that both individual and collective advances in psychological and philosophical reasoning take place against the same social background and result from socially given dilemmas and problems that individuals must confront.