Constraint-Compatibility as a Persistence Criterion in Structural Realism

Structural realism maintains that relational structure survives theory change yet lacks a fully articulated mechanism explaining why structural continuity persists across revolutions. This paper introduces the Constraint-Compatibility Persistence Law (CCSL), a domain-neutral persistence criterion stating that identity persists only within admissible constraint regions. Structural survival is explained as compatibility-filtered continuation rather than accidental retention. A formal lemma, boundary analysis, and falsifiability condition are provided. The framework applies across scientific, psychological, biological, social, and formal domains, demonstrating that persistence depends on dynamic compatibility with operative constraint frames rather than definitional identity alone. The account is necessary but not sufficient and introduces no new physical laws, functioning instead as a structural explanatory principle.