Reinterpreting Friston’s Free Energy Principle Through the Lens of the Three Fundamental Laws of Response: Toward a Thermodynamic Grammar of Cognition

The Free Energy Principle (FEP) proposes that biological systems maintain their structural integrity by minimizing variational free energy—a quantity rooted in Bayesian inference and information theory. While theoretically elegant, FEP has often been criticized for its abstraction, overgenerality, and lack of concrete physical constraints. In this work, we offer a new interpretation: that FEP is a statistical manifestation of three underlying physical laws governing all response systems—thermodynamic saturation, information delay, and control stability. These three response laws constrain the shape and dynamics of biologically realizable functions, leading to a universal family of rational, saturating response curves. We show that under these constraints, minimizing free energy reduces to selecting admissible transfer functions that are bounded, delayed, and stable. This reinterpretation demystifies FEP, grounding it in thermodynamic and control-theoretic realities, and offering a predictive formalism to unify perception, prediction, and action within a universal response grammar.