What Do Fundamental Statements Do? Functional Roles and Ontological Determination in Physical Theories

Labels such as law, principle, postulate, and axiom group statements that perform different tasks in physical theories. This article argues that a component’s inferential warrant depends on its role within a specified theoretical architecture, not on its label. It distinguishes six functional roles and operationalizes them by three diagnostic tests. It then separates formal structure, empirical connection, and physical ontology, and analyzes ontological determination along four dimensions. Comparisons among classical mechanics, relativity, and quantum mechanics, followed by audits of complementarity and the measurement problem, show that formal precision and empirical success constrain ontology without selecting a unique realization.