Having described this problem, we want to emphasize that we are not promoting the view that the DSM system is devoid of validity. On the contrary, the DSM–IV committee conducted and published 175 qualitative literature reviews and 48 additional empirical studies to provide the scientific underpinnings of their efforts (Widiger & Clark, 2000). In fact, each new version of the DSM has relied more heavily on the available science than did previous versions, and each new version has benefited from an ever-increasing body of scientific knowledge. The progress in psychiatric diagnosis is similar to progress in other diagnostic fields (Berg & Blackstone, 2006). Indeed, to a considerable degree, the rapid growth of psychopathology research has been facilitated by the development of a diagnostic nomenclature. Our argument is that the next step in this process may be to recognize the need to describe dysfunction along homogeneous dimensions and thus not be bound by a syndromal hypothesis that lacks validity. Doing so promises to further advance the validity of the diagnostic system, certainly in terms of its theoretical clarity and, we argue below, its parsimony and utility.
