which it was designed by evolution" (Wakefield, 1992:373). The class of impulse disorders in which pathological gambling has been placed represents a set of behaviors that are violations of social mores and customs and therefore considered harmful. The dysfunctional nature of these disorders in general and pathological gambling in particular, however, remains to be determined. As we have previously indicated, mental disorders with impulsive features often have failed to satisfy the legal system's need for exculpatory conditions. These disorders have not been considered as "causal" in the scientific sense and have therefore not withstood courtroom challenges.

This matter becomes even more complicated when considering the matter of comorbidity from the perspective of DSM-IV classification. Comorbidity is the medical term used to describe the cooccurrence of two or more disorders in a single individual; comorbidity is extremely common among pathological gamblers (Crockford and el-Guebaly, 1998). The problem of conceptually distinct multiple diagnoses can be taken to suggest that pathological gamblers suffer from a variety of interactive disorders. However, there is an alternative possibility that has gained considerable support among clinicians: multiple diagnoses reflect an underlying problem with the constructs of mental disorders. The frequency of cooccurring disorders as described in the DSM suggests that these categorical distinctions exhibit "extraordinary and obstinate heterogeneity" (Carson, 1991, cited in Blatt and Levy, 1998:83-84). Given this conceptual difficulty, although we describe comorbidity issues and pathological gambling more in Chapter 4, we do not emphasize this aspect of the disorder in the report. Nevertheless the reader is encouraged to keep comorbidity issues in mind when reading the discussions that follow of pathological gambling as an impulse disorder, as an addiction, and as considered by other theories and conceptualizations.

An impulse refers to incitement to action arising from a state of mind or some external stimulus; or a sudden inclination to act, without conscious thought; or a motive or tendency coming from