Diagnosis and rational psychotherapy.

In a previous paper, the question of whether diagnosis is a prerequisite of psychotherapy was discussed. On the one hand we have Thorne's statement that "it seems elemental that rational therapy cannot be planned and executed until an accurate diagnosis has been made." On the other hand, Rogers writes that "diagnostic knowledge and skill are not necessary for good therapy." Thorne bases his argument upon an analogy between mental disease and physical disease. Consideration of the characteristics of mental and physical disease, however, raises doubt as to the appropriateness of the analogy. The nature of the disease processes differ; on the one hand, the disease primarily involves the physiology and chemistry of bodily functioning, while in mental disease it is primarily a disorder of psychologic and social behavior and adjustment. Moreover, while in physical disease etiology may be traced to specific, identifiable or empirically verifiable chemical and bacteriologic agents, or viruses, in functional mental disease no such etiology has, as yet, been verified. Finally, while in physical or internal medicine specific experimentally or empirically verified remedies exist, this is not the case in the field of psychotherapy. Thus, it is not possible in mental disease to make differential diagnoses on an etiologic basis and select the appropriate specific remedy or therapy.