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Rate-Distortion Theory and Optimal Action: A Strict Proof of Fitness Beats Truth
Target Venue: Journal of Theoretical Biology
Abstract
Donald Hoffman's "Fitness Beats Truth" (FBT) theorem argues that perception is tuned to utility, not reality. Previous attempts to prove FBT using the Information Bottleneck method fatally misidentified the causal structure of biological fitness, violating the Data Processing Inequality by placing a collider downstream of perception. We rectify this by reformulating FBT using strict Rate-Distortion Theory. By defining the distortion function directly as the negative expected fitness of the agent's optimal action (D(x, y) = -\max_a \mathbb{E}[F(x, a) \mid y]), we completely bypass the causal collider trap. We mathematically prove that minimizing this distortion under a strict channel capacity bound C forces the optimal perceptual mapping p(y|x) to completely obliterate structural isomorphism.
1. Introduction
Fitness F is a causal collider of World X and Action A. Thus, modeling X \to Y \to A \to F as a linear Markov chain breaks basic causal inference. We must define distortion through expected optimal action.
2. Rate-Distortion over Expected Utility
The agent possesses a channel capacity C for the mapping X \to Y.
Instead of tracking mutual information to F, we embed fitness directly into the distortion metric. The perceptual distortion when state X=x is mapped to Y=y is defined as the loss of expected utility:
D(x, y) = -\max_a \mathbb{E}[F(x, a) \mid y]
3. Minimizing Distortion Destroys Isomorphism
The organism must find the mapping p(y|x) that minimizes the expected distortion \sum_{x,y} p(x)p(y|x)D(x,y) subject to the capacity constraint I(X;Y) \le C.
Because the fitness landscape F(X, A) generically possesses symmetries and gradients completely orthogonal to the metric topology of X, the optimal reconstruction Y will aggressively cluster topologically distant points in X that share identical fitness payoffs.
Any bits of the strictly limited capacity C spent on distinguishing points with identical fitness payoffs strictly increase the expected distortion. Therefore, the optimal perceptual channel mathematically forbids structural isomorphism.
4. Conclusion
By correctly defining biological distortion as expected utility loss, standard Rate-Distortion theory proves that bounded capacity organisms must abandon truth to optimize survival.
References
- Hoffman, D. D., Singh, M., & Prakash, C. (2015). The interface theory of perception. Psychonomic Bulletin & Review.
- Berger, T. (1971). Rate Distortion Theory. Prentice-Hall.