The biopsychosocial model, which was deeply influential on psychiatry following its introduction by George L. Engel in 1977, has recently made a comeback. Derek Bolton and Grant Gillett have argued that Engel’s original formulation offered a promising general framework for thinking about health and disease, but that this promise requires new empirical and philosophical tools in order to be realized. In particular, Bolton and Gillett offer an original analysis of the ontological relations between Engel’s biological, social, and psychological levels of (...) analysis. I argue that Bolton and Gillett’s updated model, while providing an intriguing new metaphysical framework for medicine, cannot resolve some of the most vexing problems facing psychiatry, which have to do with how to prioritize different sorts of research. These problems are fundamentally ethical, rather than ontological. Without the right prudential motivation, in other words, the unification of psychiatry under a single conceptual framework seems doubtful, no matter how compelling the model. An updated biopsychosocial model should include explicit normative commitments about the aims of medicine that can give guidance about the sorts of causal connections to be prioritized as research and clinical targets. (shrink)