variational free energy

Compiled with AI assistance and selectively reviewed. Please consult the cited passages; the books remain the authoritative source. About this companion

Editorial synthesis · provisional

Definition

Variational free energy is the formal quantity that RB2 describes as bounding surprise within active inference and being reduced through belief updating or action securing expected sensory states. It is explicitly distinct from thermodynamic free energy. The proposed entry keeps the analogy and its biological ambitions separate from a demonstrated identity between physical energy, meaning, inference and every form of living persistence.

Explanation

The direct passage places the quantity within Friston’s formal treatment of prediction and action. Its relation to surprise explains the language of updating and selecting sensory states. The local material supplies no equation here that would justify inventing a numerical method or calculating an organism’s energy consumption from the term alone.

RB2 deliberately distinguishes this formal usage from thermodynamic free energy while retaining an analogy concerning constrained persistence. Its discussion of metabolic costs keeps nervous activity material. An energetic requirement, however, does not by itself establish a modeling relation, semantic significance or the stronger claim that life literally performs Bayesian inference.

The text records criticism concerning near-tautological generality, stationarity and statistical boundaries, then explicitly states the as-if status of the framework. The proposed entry preserves those qualifications rather than elevating a powerful formal vocabulary into a settled universal ontology or treating objections as already resolved by the analogy.

Scope and attribution

Retain formal scope, the explicit analogy and unresolved foundational qualifications.

AB — The Actual Book

Source-verified occurrence; see the printed-page references below.

Occurrence locators: Notes: 242.

RB2 — The Real Book, Volume II: Becoming Is Being

A formal bound is distinguished from thermodynamic energy and qualified by foundational objections.

Occurrence locators: 116, 121, 122, 134.

Background used in the editorial explanation

Variational free energy is distinguished from thermodynamic cost; the source’s qualification remains explicit.