We establish that the closed quartic Psi–Gamma variational functional is not one possible model among alternatives, but the unique structure compatible with the existence of non-trivial, stable, and self-contained physical systems. Starting from minimal conditions of existence, stability, absence of external structure, and non-degenerate spectral behavior, we derive a complete set of admissibility constraints. We show that any variational functional satisfying these conditions must necessarily reduce, up to internal isomorphism, to a single form. All alternative constructions are excluded by structural failure, leading to degeneracy, instability, loss of closure, or external dependence. The result implies a collapse of the space of admissible theories to a singleton. The absence of alternatives is not assumed, but follows as a direct consequence of the admissibility conditions.
Livolsi Edoardo (Thu,) studied this question.