Wakefield's harmful dysfunction analysis of mental disorder is among the most rigorous and thoughtful attempts to address serious conceptual problems that beset the foundations of abnormal psychology. According to Wakefield, disorder is a hybrid concept comprising a factual component specifying derangement in a naturally-selected function, and a value component specifying the resultant harm. It is unclear, however, whether an evolutionary interpretation of dysfunction is either feasible or necessary; a nonhistorical causal role analysis of psychological function may enable ascription of disorder (assuming resultant harm). Moreover, the dysfunction component itself appears hybrid, comprising both a factual assertion about the state of a mechanism and a normative assertion implying that the mechanism is not functioning as it ought be.