Abstract
Lennard Davis’s Biocultural Critique of the alleged certainty of diagnosis (Davis Journal of Bioethical Inquiry 7:227−235, 2010) makes errors of fact concerning psychiatric diagnostic categories, misunderstands the role of power in the therapeutic relationship, and provides an unsubstantiated and vague alternative to the management of psychological distress via a conceptually outdated model of the relationships between physical and psychological disease and illness. This response demonstrates that diagnostic knowledge vouchsafes legitimate power to physicians, and via them relief to patients who suffer from psychological distress. The history of medicine and psychiatry demonstrates that psychiatric diagnosis shares many features with physical diagnosis, while there is also reason to believe that the two types will continue to be distinct in some respects. Diagnostic categories in psychological medicine, like those in physical medicine, are provisional, probabilistic, and often uncertain. These features do not detract from the dependence on diagnosis of therapeutic efficacy in both domains