Metatheoretical and, more generally, methodological analyses of psychological problems and theories have a long tradition; however, their impact on scientific practice, especially on the clarification and testing of existing psychological theories and the formulation of new ones, has so far been less than spectacular. The increased interest in theoretical psychology visible during the past ten or twenty years is associated with the hope that a change of this situation will gradually be effected. Thus, in their preface to the proceedings of the founding conference of The International Society...