The first decades of the 21st century have seen increasing dissatisfaction with the diagnostic psychiatry of the American Psychiatric Association’s Diagnostic and Statistical Manuals (DSMs). The aim of the present discussion is to identify one source of these problems within the history of medicine, using melancholy and syphilis as examples. Coinciding with the 19th‐century beginnings of scientific psychiatry, advances that proved transformative and valuable for much of the rest of medicine arguably engendered, and served to entrench, mistaken, and misleading conceptions of psychiatric disorder. Powerful analogical reasoning based on what is assumed, projected, and expected (and thus occupying the realm of the medical imaginary), fostered inappropriate models for psychiatry. Dissatisfaction with DSM systems have given rise to alternative models, exemplified here in (i) network models of disorder calling for revision of ideas about causal explanation, and (ii) the critiques of categorical analyses associated with recently revised domain criteria for research. Such alternatives reflect welcome, if belated, revisions.