Functional explanations require a real causal feedback loop through a group.

Evidence

An institution or behavioral pattern X is explained by its function F for group G if and only if it fits the following paradigm: … 3. F maintains X by a causal feedback loop passing through G (Elster 1979, 28). — Russell Hardin, Trust and Trustworthiness, 666

Categorization

• DEFINE: Formalizes Elster’s demanding paradigm for what counts as genuine functional explanation, distinguishing it from shallow metaphor.