Gray-zone concepts are built by joining necessary conditions with negations of the two poles.

Evidence

Notice that equation (7.1) is exactly the hybrid structure described above that is so common in the DSM and which is used for ideal type mental disorders. The key feature that differentiates that ideal type use and its use for the gray zone is the fact that the necessary conditions are typically negations of the poles of the concept pair. So it is the combination of necessary conditions and negation of the poles that constitutes a common generic way of doing hybrid concept structures for the gray zone. — Gary Goertz, Social Science Concepts and Measurement, 1151

Categorization

• DEFINE: The book’s central technical move: to capture the middle, you specify the poles and then negate each — NOT-full-authoritarianism plus NOT-full-democracy.
• XREF: Mirrors the Schaffer–Collier ‘shifting standards’ problem: defining the middle by what it is not, rather than by independent positive content.