Validity without legitimacy? Reconsidering the diagnostic defence of borderline personality disorder: Response to Ruffalo, 2026

Ruffalo argues that borderline personality disorder (BPD) meets Robins and Guze criteria for diagnostic validity and should be retained as a legitimate psychiatric diagnosis. This response challenges that conclusion, arguing that mid twentieth century biomedical validation models are inadequate for evaluating a construct that regulates identity, relationality, and social deviance. Although BPD may satisfy traditional validators, this does not establish epistemic soundness, ethical defensibility, or clinical legitimacy. Drawing on feminist, decolonial, neurodiversity, and lived experience-led scholarship, this analysis highlights diagnostic circularity, structural harm, and the exclusion of lived experience evidence. Validity without legitimacy is insufficient for mental health care.