 By adopting a thoroughgoing biological reductionism it will be possible (although not necessary), to accept as dispositive the parallel between psychiatric categories and other categories recognized as natural kinds on non-essentialist definitions. But, although the diverse ends to which disease taxonomies can be put argue against finding a single answer about the kind status of mental disorders, focus on the purposes served by disorder language and categories has proven fruitful, here. (i) Mental illnesses have been assigned to a category of “practical kinds”, where membership in this class depends on some external criterion that is pragmatically relevant in the clinical context, such as a certain degree of functional impairment, and remains unrelated to the underlying structure of the kind (Zachar 2014). Along with practical kinds, moreover, mental disorders may be further classified according to their status as dimensional, discrete, and fuzzy kinds, and there is little reason to suppose mental disorders are all of one kind (Haslam 2002, 2014). (ii) Whether or not they exhibit the stability required of classifications into true natural kinds, mental illnesses do possess the properties relevant, and sufficiently stable, to guide clinical treatment, as Şerife Tekin illustrates using the lack of illness awareness (“insight”) common in patients with some diagnoses. A settled self-conception that involves being mistakenly seen as ill can be effectively treated using trust-building strategies that avoid medical language forcing the subject to explicitly acknowledge illness (Reimer 2010; Tekin 2016).