Overlapping categories arise both conceptually and empirically, producing comorbidity by definition.

Evidence

Within the DSM the problem of overlapping disorders is quite massive. It is quite common that an individual person shows symptoms of multiple disorders. It is important to understand that this is both empirical as well as conceptual. The conceptual part comes in because the same symptom might be part of multiple disorders. This is what one might call “conceptual comorbidity,” which means that the individual has both disorders at least partially by definition. “Empirical comorbidity” would be if the symptoms of each disorder are completely separate but the individual had the symptoms of both disorders. — Gary Goertz, Social Science Concepts and Measurement, 1258

Categorization

• DEFINE: Introduces a sharp distinction between ‘conceptual comorbidity’ (shared symptoms built into the definitions) and ‘empirical comorbidity’ (genuinely separate symptom sets that co-occur).
• XREF: Generalizes the coding problem seen in typologies of autocratic regimes, where hybrid cases straddle the main types.