The American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders (DSM) has for decades been a locus of dispute between ardent defenders of its scientific validity and vociferous critics who charge that it covertly cloaks disputed moral and political judgments in scientific language. This essay explores Alasdair MacIntyre's tripartite typology of moral reasoning--"encyclopedia," "genealogy," and "tradition"--as an analytic lens for appreciation and critique of these debates. The DSM opens itself to corrosive neo-Nietzschean "genealogical" critique, such an analysis holds, only insofar as it is interpreted as a presumptively objective and context-independent encyclopedia free of the contingencies of its originating communities. A MacIntyrean tradition-constituted understanding of the DSM, on the other hand, helpfully allows psychiatric nosology to be understood both as "scientific" and, simultaneously, as inextricable from the political and moral interests--and therefore the moral successes and moral failures--of the psychiatric guild from which it arises.