2205.11543
On Bayesian Mechanics: A Physics of and by Beliefs
Maxwell J. D. Ramstead, Dalton A. R. Sakthivadivel, Conor Heins, Magnus Koudahl, Beren Millidge, Lancelot Da Costa, Brennan Klein, Karl J. Friston
incompletemedium confidence
- Category
- Not specified
- Journal tier
- Specialist/Solid
- Processed
- Sep 28, 2025, 12:56 AM
- arXiv Links
- Abstract ↗PDF ↗
Audit review
The paper correctly asserts the Gibbs form p(x) ∝ e^{-λ J(x)} and the parallel-transport differential relation dp = −λ p dJ (equivalently ∂x log p = −λ ∂x J), and sketches a gauge-theoretic interpretation of constrained maximum entropy (see eqs. (6–9) and (10), and the claims “p(x)=e^{−λJ(x)}” and “maximum of entropy is parallel transport” ). However, the derivation omits the normalization constraint multiplier α and subsequently makes the imprecise claim that the “−1” term can be absorbed into λ (footnote 17), which mixes a constant with the multiplier of J(x) and obscures the necessary normalizing constant Z(λ) ( ). The candidate solution provides the standard, complete variational treatment with both constraints, the partition function, and the conditions for existence/uniqueness of λ, and derives the same dp = −λ p dJ relation rigorously. Hence, the model’s solution is correct and technically complete, while the paper’s argument is sound in essence but technically incomplete.
Referee report (LaTeX)
\textbf{Recommendation:} minor revisions \textbf{Journal Tier:} specialist/solid \textbf{Justification:} The paper offers a cogent and timely bridge between constrained maximum entropy and gauge-theoretic notions of covariance and parallel transport, aligning well with current interest in the FEP/CMEP duality. The core mathematical statements (Gibbs form and parallel-transport ODE) are essentially correct, but the derivation is informal in places: the normalization constraint multiplier is omitted, the constant term in the Euler–Lagrange condition is handled imprecisely, and standard existence/uniqueness conditions are not stated. These are straightforward to fix and do not affect the main claims.