Classification and diagnosis

Psychiatric research and practice rest on empiricist convention rather than on timeless discovery. The principal classification systems, the International Classification of Diseases (ICD) and the Diagnostic and Statistical Manual of Mental Disorders (DSM), are shaped by contemporary notions about what constitutes a real disorder, what counts as scientific evidence, and how research should be conducted. They are Western cultural documents par excellence.3

The diagnostic categories within these classifications are essentially conceptual devices emerging from committee decisions. The authors of both of these classifications are careful to point out that “there is no assumption that each category of mental disorder is a completely discrete entity with absolute boundaries dividing it from other mental disorders or from no disorder.”4 Despite this, in everyday practice these categories have been effectively accepted as if they were unequivocal diseases like, say, tuberculosis.

Claims for the universality of a particular psychiatric category would be compelling if a straightforward biological cause had …