Rethinking Categories and Dimensions in the DSM.

This paper addresses the role of categories and dimensions in the classification of psychopathology. While psychopathology does not sort itself out neatly into natural categories, we do find rough, symptom-based groupings that, through refinement, become diagnostic categories. Given that these categories suffer from comorbidity, uncertain boundaries, and excessive "unspecified disorder" diagnoses, there has been a move toward refining the diagnoses with dimensional measures. The paper traces efforts both to improve the diagnostic categories with validators that allow at least partial validity and to introduce dimensional measures into the diagnostic manual. Drawing from the philosophical pragmatism of Charles Sanders Peirce, William James, and John Dewey, which emphasizes the practical, effect-sensitive consequences of a theory along with an emphasis on empirical evidence and the progressive, probabilistic character of knowledge, the paper argues that these efforts must be guided both by scientific validity and clinical utility.