Most mainstream psychologists consider philosophy irrelevant to their work, but see themselves as realists. Various opposition movements embrace philosophy but reject realism, either completely or partially, despite upholding ideas consistent with a realist philosophy. Many on both sides see the Tower of Babel that constitutes psychology as a sign of healthy diversity, not fragmentation. We argue that relations among the three factors – philosophy, realism and fragmentation – deserve closer scrutiny. With philosophy’s core method of conceptual analysis deprioritized, both mainstream (...) psychology and the opposition fracture into an array of “partial realisms”, falling away from a realism that is thoroughly consistent. These are the source of psychology’s fragmentation. The conceptual neglect and resulting confusions can be seen in psychology’s recent replicability crisis, and in the widespread adoption of a representationalist approach to the mind/brain. We argue that the metatheoretical coherence and methodological maturity required for genuine scientific progress involves a consistent adherence to realism. We spell out what that involves and consider several reasons why this has been so difficult for psychology. (shrink)