Overlapping symptom criteria mean DSM mental disorders are not qualitatively distinct.

Evidence

It is the Scope Guideline that defines the universe of the phenomenon. Within that scope, objects range from 0 to 1 (according to the convention adopted in this volume). Whether two concepts are qualitatively different is a separate question. They may or may not be, depending on their definitions and ontologies. The DSM disorders illustrate this in a big way (DSM is the bible for defining mental disorders, the current version is DSM-5 2013). Many symptoms appear for various different mental disorders. Thus these disorders overlap and are not “qualitatively different.” — Gary Goertz, Social Science Concepts and Measurement, 401

Categorization

• XREF: Connects to psychiatric classification debates (comorbidity, dimensional vs. categorical diagnosis) and could be checked against Hofstede-style dimension models discussed elsewhere in the book.