Mental disorder as a Roschian concept: a critique of Wakefield's "harmful dysfunction" analysis.

J. C. Wakefield (1992a, 1992b, 1993) recently proposed that mental disorder is best conceptualized as a "harmful dysfunction," whereby "harm" is a value judgment regarding the undesirability of a condition, and "dysfunction" is the failure of a system to function as designed by natural selection. The authors maintain, however, that (a) many mental functions are not direct evolutionary adaptations, but rather adaptively neutral by-products of adaptations, (b) Wakefield's concept of the evolutionarily designed response neglects the fact that natural selection almost invariably results in substantial variability across individuals, and (c) many consensual disorders represent evolutionarily adaptive reactions to danger or loss. The authors propose that mental disorder is a Roschian concept characterized by instrinsically fuzzy boundaries and that Wakefield's analysis may only prolong scientific debate on a fundamentally nonscientific issue.