Fellow control theorists,
For years we have watched the Free Energy Principle absorb every objection thrown at it, the way a good attractor absorbs a disturbance. Say it predicts the wrong thing and you are told it is only a tautology. Point at the tautology and you are told it explains schizophrenia, dopamine, and the price of tea. I finally decided to stop arguing with the shield and audit the structure behind it.
The result is a new paper and a companion page. Both do the same thing, one long, one short: state the strongest possible version of FEP first — a real steelman, no straw men — and then test four faults against one hard piece of evidence each.
The four faults, in brief:
1. **The category error.** FEP encodes a *goal* as a *high-precision prediction*. But wanting and expecting can point in opposite directions, and the neurobiology agrees: motor intentions in tetraplegia persist for years, stable, unconfirmed, refusing to decay to “minimise surprise.” That is a reference signal being defended, not a prior being updated. We have known this since 1973.
2. **The Dark Room.** Take the principle at its word and the ideal environment is a silent, perfectly predictable cell — a homeostatic paradise. Biology calls it solitary confinement. Deprived of a signal to control, the nervous system does not relax into zero-error bliss; it manufactures its own hallucinations rather than accept the silence. The “Expected Free Energy” patch that supposedly fixes this is an epicycle, bolted on precisely because the base axiom points the wrong way.
3. **The unfalsifiability shield.** Two theories wearing one name: an untouchable mathematical identity when you attack the biology, a fertile empirical mechanism when you attack the maths. It is never both in the same sentence, and never the same one twice under pressure.
4. **The broken lemma.** This one is not mine — Biehl, Pollock & Kanai (Entropy, 2021) worked through the mathematics line by line and proved by counterexample that the original free energy lemma, taken at face value, is wrong, and that the Markov-blanket definitions are not even equivalent across Friston’s own papers. The universal generalisation is exactly the part that fails to generalise.
Then the part I suspect this forum will most enjoy: a full section on what would falsify *my own* critique — the one discipline the audited framework never imposes on itself. If we are going to charge FEP with dodging refutation, we cannot dodge it ourselves.
The conclusion writes itself in our vocabulary. FEP is not a theory of life waiting to be completed. It is a description of control waiting to be recognised as one. The organism does not minimise surprise. It controls perception. Powers had the loop closed while everyone else was still drawing straight lines.
Page: A Structural Audit of the Free Energy Principle — Perceptual Control Theory
Paper (V1, CC BY 4.0): The Description Dressed as a Law: A Structural Audit of the Free Energy Principle and the Case for Perceptual Control | Zenodo
I would genuinely welcome the hardest pushback this group can produce — especially on fault 4, where I want to be certain I am representing the Biehl–Pollock result precisely and not one millimetre further than it licenses. Tear into it.
Luk