Abstract Some foundational claims in physics demand more than regime-local explanatory success: they require a theory to physically explain the conditions of its own applicability. We introduce a diagnostic signature — S7 (Self-Applicability Demand) — that identifies this structural pattern. S7 triggers when a theoretical claim treats the licensing conditions governing the theory’s explanatory apparatus as physical explananda rather than disclosed framework commitments. We show that any attempt to satisfy this demand terminates in one of exactly three ways: unargued postulate, explanatory circle, or explicit frame-exit. Using a diagnostic tuple ⟨Claim, Regime, Starter-Package, Interface, Measure⟩ and a minimal set of applicability conditions, we derive a structural boundary result: no element of the tuple can carry the self-licensing burden without presupposing another element whose capacity to do so has already been shown to fail. The result is established through five sublemmata, each targeting one tuple element, and assembled into a proposition demonstrating the structural non-achievability of explanatory completeness regarding licensing conditions. We apply S7 to three prominent claim-forms — the Theory of Everything as self-explaining, the unification imperative as physically mandatory, and the Mathematical Universe Hypothesis — and provide reformulation directives that preserve scientific content while discharging the self-applicability demand. A reflexive self-test confirms that the diagnostic framework survives S7 by practising presupposition disclosure rather than presupposition elimination. We propose a Default = OPEN policy for finality claims, justified by the asymmetric costs of premature acceptance versus additional scrutiny. Keywords applicability of physics, self-reference, diagnostic protocols, explanatory completeness, levels of description, philosophy of physics
Zierhut et al. (Sat,) studied this question.