Abstract

Wakefield’s “hybrid” theory of mental illness defines the (dys)function of mental traits in terms of the evolutionary account of biological functions known as the Selected-Effect Theory. This evolutionary framework, however, has been subject to serious challenges in recent decades. Accordingly, the article sets out—programmatically and through a detailed literature review—an appraisal of hybrid accounts of mental health in light of debates around the philosophy of biological functions. Our analysis proceeds in two stages. First, it extends and systematizes three central critiques to the Selected-Effect Theory to Wakefield’s account: (i) the explanatory inadequacy of historical and population-based accounts of function for defining mental illness, (ii) the possibility that the origins and persistence of mental traits may resist functional explanation, and (iii) the claim that functional explanations of the mind’s evolution extend beyond selection-based accounts. Second, we explore alternative frameworks through which biological theories of function can shape the definition of mental illness—particularly the causal-role theory and the organizational account.