Theoretical propositions require symbols with substantive empirical content.

Evidence

JOHN STUART MILL began his System of logic with a “book” devoted to concepts. Starting with concepts was a logical choice since they are key building blocks for constructing theoretical propositions. Propositional logic involves the proper manipulation of symbols. For this to have usefulness in science, these symbols need substantive and empirical content. — Gary Goertz, Social Science Concepts and Measurement, 29

Categorization

• XREF: Connects to the reader’s corpus of conceptual-methodology works, e.g. Sartori and Collier on concept formation.