Diagnosing DSM-IV--Part II: Eysenck (1986) and the essentialist fallacy.

In Part I (Wakefield, 1997, Behaviour Research and Therapy, 35, 633-649) of this two-article series, I used the harmful dysfunction analysis of the concept of disorder (Wakefield, 1992a, American Psychologist, 47, 373-388) to 'diagnose' a problem with DSM-IV. I argued that DSM-IV diagnostic criteria often violate the 'dysfunction' requirement by invalidity classifying harms not caused by dysfunctions as disorders. In Part II, I examine Eysenck's (Eysenck, 1986, Contemporary directions in psychopathology: Toward the DSM-IV) argument that DSM commits a 'categorical fallacy' and should be replaced by dimensional diagnoses based on Eysenckian personality traits. I argue that Eysenck's proposed diagnostic criteria violate the 'harm' requirement by invalidly classifying symptomless conditions as disorders. Eysenck commits an 'essentialist fallacy'; he misconstrues 'disorder' as an essentialist theoretical concept when in fact it is a hybrid theoretical-practical or 'cause-effect' concept. He thus ignores the harmful effects essential to disorder that are captured in DSM's symptom-based categories.