Ordinary concepts are degree membership sets measured by fuzzy-logic thresholds

Evidence

When an attendant says that the plane is full, it generally does not mean that all seats are occupied. It seems that if 90–95 percent of the seats are occupied, that counts as full. If, in fact, all seats are occupied then an attendant will use other expressions like “no empty seats” to mean “completely full.” Expressions like “very full” for a literalist make no sense, but almost everyone understands what is meant. At some point, maybe at about 80–90 percent of seats, an attendant would never use the term full at all but instead might say that the plane is “pretty full.” — Gary Goertz, Social Science Concepts and Measurement, 575

Categorization

• DEFINE: Clarifies what a ‘semantic transformation’ is: a mapping between the meaning of a concept (full) and its data indicator (seats occupied), producing a fuzzy [0,1] membership score.
• SEED: An essay or explainer on ‘how words secretly carry numbers’ — everyday vague predicates (full, tall, rich, heavy) as social science’s real measurement problem.