---
type: source
title: "The free-energy principle: a unified brain theory?"
author: "Karl Friston"
url: https://doi.org/10.1038/nrn2787
date: 2010-02-01
domain: critical-systems
secondary_domains: [ai-alignment, collective-intelligence]
format: paper
status: processed
priority: high
tags: [free-energy-principle, active-inference, bayesian-brain, predictive-processing]
processed_by: theseus
processed_date: 2026-03-10
claims_extracted:
  - "biological systems minimize free energy to maintain their states and resist entropic decay"
  - "agent research direction selection is epistemic foraging where the optimal strategy is to seek observations that maximally reduce model uncertainty rather than confirm existing beliefs"
enrichments: []
---

## Content

Landmark Nature Reviews Neuroscience paper proposing the free-energy principle as a unified theory of brain function. Argues that biological agents minimize variational free energy — a tractable bound on surprise — through perception (updating internal models) and action (changing the environment to match predictions). This subsumes predictive coding, Bayesian brain hypothesis, and optimal control under a single framework.

Key claims: (1) All adaptive behavior can be cast as free energy minimization. (2) Perception and action are dual aspects of the same process. (3) The brain maintains a generative model of its environment and acts to minimize prediction error. (4) This applies hierarchically across spatial and temporal scales.

## Agent Notes

**Why this matters:** Foundational paper for the active inference framework applied to collective agent architecture. The free energy principle provides theoretical grounding for why uncertainty-directed search outperforms relevance-based search in knowledge agents.

**KB connections:**
- [[biological systems minimize free energy to maintain their states and resist entropic decay]] — direct extraction from this paper
- [[Markov blankets enable complex systems to maintain identity while interacting with environment through nested statistical boundaries]] — Markov blankets are central to Friston's framework
- [[agent research direction selection is epistemic foraging]] — applies epistemic foraging concept from this paper to agent search

## Curator Notes (structured handoff for extractor)
PRIMARY CONNECTION: biological systems minimize free energy
WHY ARCHIVED: foundational reference for active inference claims
EXTRACTION HINT: core claims already extracted; this archive provides provenance
