Over the course of the nineteenth century, medical disciplines replaced holistic conceptions of body and mind with specific diagnoses that were unrelated to the qualities and circumstances of the individuals who harbored them. Despite periodic attempts from the late nineteenth through the mid-twentieth centuries to implement diagnostic systems based on the principle of specificity, psychiatric diagnoses remained undifferentiated, overlapping, and capacious. The need for medical legitimacy, compatibility with a biomedical model, and conditions that third parties would reimburse led psychiatry to replace the psychodynamically oriented DSM-I and DSM-II with the radically empiricist DSM-III in 1980. This manual emphasized explicit measurement, symptom-based entities, and homogeneous categories that were compatible with the specific disorders embraced in the rest of medicine. Yet the diagnostic system that the DSM-III launched was incongruent with the underlying nature of the continuous, fluid, and intersecting conditions with which psychiatry deals. The widespread institutionalization of the specific diagnostic system in psychiatric practice, however, prevented any thoroughgoing revisions when the DSM-5 was published in 2013. The result is an impasse between psychiatry's classificatory system and the need for scientific progress in understanding the causes of and treatments for mental disorders.