Diagnostic Validity Revisited

Key points

Many medical conditions exist on spectra; psychiatric conditions are no different.

Dimensionality does not determine whether diagnostic categories reflect valid syndromes.

Validity concerns how well diagnoses match real patterns that exist in the world.

In contemporary philosophy of psychiatry, one increasingly hears the claim that if mental disorders turn out to be dimensional, the very idea of diagnostic validity may no longer be very important. Dimensionality here refers to the idea that symptoms vary along continuous spectra rather than forming discrete, sharply bounded categories. According to this view, once we accept the presence of broad dimensional structures, traditional efforts to determine whether psychiatric diagnoses correspond to real syndromes become outd