Among the obstacles to the integration of competing theories in psychology is that it is unclear why and how they differ. Some thoughtful speculations have been offered for why they differ, but they remain preliminary. A plethora of schemes has been proposed for analysing how theories differ, but there is no convincing basis for choosing among these schemes. Furthermore, several kinds of relationships can be identified between apparently competing theories, each of which has implications for the potential integration of those (...) theories. If theories X and Y seem to be competing, they may (a) turn out to be intertranslateable, in which case they are not really competing; they may (b) be truly contradictory, and therefore logically impossible to integrate; and may (c) be apparently but only superficially mutually translatea-ble, but with the translation doing violence to at least one of the theories; or they may (d) be mutually irrelevant, so that there is little point in trying to integrate them, and any attempt at integration is apt to be little more than a minimally organised list. (shrink)