Written by Oliver Cás — physician specializing in the diagnosis of rare brain diseases (neuropathology) and author. See Oliver Cás's books →
Philosophy of Mind
Free Will After Libet
In 1983, a simple experiment seemed to take from the human being what was most intimate: authorship of one's own acts. The brain, Benjamin Libet showed, began preparing the movement before you decided to move it. Four decades on, the hasty conclusion has aged badly — but the question it opened has not.
◈ The window of experience
From the inside, nothing is more self-evident than choice. I hesitate between two paths, weigh reasons, decide. On that evidence rests nearly everything we call human: moral responsibility, guilt, merit, the very sense of being an agent rather than an object being pushed.
Philosophy calls compatibilism the view that this freedom is real even in a world of causes: to be free is not to escape causality, it is to act according to one's own reasons, without external coercion. An act is mine when it springs from what I am — my values, deliberations and character — even if all of that has, in turn, a history.
⚕ The window of the laboratory
ElectrophysiologyNeuroimaging
Libet asked volunteers to move the wrist whenever they wished, noting the instant of conscious intention. The readiness potential — preparatory electrical activity — arose hundreds of milliseconds before that instant. John-Dylan Haynes, using fMRI, went further: brain patterns predicted the choice up to seconds before awareness of it. Daniel Wegner called conscious will a "useful illusion".
The sensationalist reading was immediate: if the brain decides first, the conscious decision is theatre. But the replications brought sobriety. Aaron Schurger proposed that the readiness potential is not an "early decision" but neural noise accumulating toward a threshold — the brain did not decide, it merely fluctuated. And there is the more obvious limit: pressing a button at random is nothing like deciding to change careers.
The border — what one language cannot say in the other
The laboratory measures the timing of neural precursors of trivial, arbitrary movements. It has not observed — nor can it, with those tools — a deliberation with reasons, values and consequences. And even if it mapped in full the causal chain of a choice, the question no electrode answers would remain: is that chain me acting, or something happening in me? Neuroscience describes the mechanism; whether the mechanism is the agent or merely its instrument is a conceptual question, not an experimental one.
Why this matters clinically and morally
Whoever works with the brain as tissue lives with a daily paradox: seeing the mind reduce to matter — a lesion changes character, a tumor alters judgment — and, at the same time, treating the patient as a responsible, dignified person, author of their story. There is no contradiction in this, but rather the two windows. That the self has a substrate does not dissolve it, just as knowing the chemistry of the paint does not erase the painting. The rush to declare freedom an illusion tends to far exceed what the data license.
"Man can do what he wills, but he cannot will what he wills." — Arthur Schopenhauer
⚖ What science does NOT say
- Libet did not prove free will is an illusion — his experiments concern arbitrary movements, not deliberated choices.
- Models such as Schurger's reinterpret the readiness potential as accumulating noise, not an "anticipated unconscious decision".
- The existence of neural precursors of a choice is compatible with compatibilism — having a causal substrate is not the same as not being the author of the act.
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