Free will is the idea that people can make genuine choices, so that what they do is up to them and not simply the unavoidable result of earlier events. Most of us live as though we have it. We deliberate, we blame and praise, we make promises. Yet two lines of argument, one from physics and philosophy and one from brain experiments, have convinced some thinkers that the feeling of choosing is misleading. Others think the case against has been overstated, and a good number think the whole dispute rests on a misunderstanding of what free will needs to be.

This article sorts the main positions, explains the famous brain studies and their weak points, and says plainly what remains unsettled.

What is the free will problem?

The puzzle begins with determinism, the claim that the state of the world at one time, together with the laws of nature, fixes everything that comes after. If that were true of your brain too, then your choice this morning was settled long before you were born, and it seems odd to say you could have done otherwise.

Philosophers separate several versions. Causal determinism is the one most relevant to science. Logical determinism says every statement about the future is already true or false. Theological determinism says a god’s decree or foreknowledge fixes outcomes. Modern physics complicates the first: quantum mechanics seems to introduce randomness at the smallest scales, although how to interpret it is still debated.

The problem, then, is a clash between a deep intuition that we author our actions and a picture of nature in which causes lead to effects. How the clash is resolved depends on what one takes “free will” to mean, and that definitional choice does a great deal of the work.

What are the main positions?

Four camps cover most of the ground.

  • Compatibilists hold that free will and determinism can both be true. Classical versions, from Thomas Hobbes and David Hume, equate freedom with acting without external constraint. Modern versions, from Harry Frankfurt and Daniel Dennett among others, treat it as a capacity: acting for reasons, responding to considerations, reflecting on your own desires.
  • Libertarians (in the metaphysical sense, nothing to do with politics) say determinism is false and free will is real. Some rely on a non-physical mind. Others look to indeterminism in nature, arguing that choices are not fully fixed by prior causes.
  • Hard determinists accept determinism and deny free will.
  • Hard incompatibilists, such as Derk Pereboom, go further and say free will is impossible whether the world is deterministic or not. Galen Strawson’s pessimism about the subject belongs here.

Each has a pressure point. Compatibilists are accused of changing the subject, since the freedom they defend may not be the one people care about. Libertarians face the objection that indeterminism looks like luck and not control: if a random event tips your decision, in what sense did you do it? The hard-incompatibilist position says that dilemma never goes away.

Don’t quantum effects rescue free will?

They are often invoked, and the argument is shaky. Models that use random events at the atomic level hope those events could influence brain activity and leave room for libertarian freedom. But a reference summary calls the causal role of such events over the odds of what happens questionable and says it is far from established that brain activity is affected this way at all.

There is a conceptual problem too. Randomness is not the same as control. Niels Bohr is reported to have seen no connection between indeterminism in nature and freedom of the will. Whether quantum indeterminacy is even relevant to free will is contested, so it is safest to treat it as an open idea, not support.

What did the Libet experiment show?

Neuroscience entered the debate in the early 1980s with the physiologist Benjamin Libet. Volunteers were asked to flick a wrist whenever they felt like it, and to note the position of a fast-moving clock hand at the moment they first felt the urge. Meanwhile electrodes picked up a slow build-up of electrical activity over the scalp called the readiness potential, discovered by Hans Kornhuber and Lüder Deecke in 1965.

The readiness potential began roughly half a second before the moment people reported deciding. Many readers concluded that the brain starts the act before the person is aware of choosing, and so awareness is not the cause.

Libet himself did not draw that conclusion fully. He proposed that conscious will might retain a power of veto in the last moments, a notion nicknamed “free won’t”. The result has been cited, discussed and argued about ever since, partly because it is easy to state and hard to interpret.

Can brain scans predict a decision in advance?

Later studies pushed in the same direction. In 2008 a team led by John-Dylan Haynes used functional MRI and pattern analysis to predict whether 12 volunteers would press a left or right button, with about 60 percent accuracy, several seconds before they reported deciding. Sixty percent is better than a coin toss, which is 50, but far from certainty. A 2013 follow-up by Soon, He, Bode and Haynes reported prediction up to about four seconds ahead for a choice between adding and subtracting.

A 2011 study in the journal Neuron recorded single brain cells in epilepsy patients who had electrodes implanted for clinical reasons. It reported that individual neurons fired about 700 milliseconds before the person’s reported will to act, and that activity predicted the choice with better than 80 percent accuracy.

Each finding shows that brain activity linked to an upcoming movement can be detected before people say they decided. It does not show that no decision was made, and that distinction is where the argument turns.

What are the objections?

There are many, and they are not trivial.

In 2012 Aaron Schurger, Jacobo Sitt and Stanislas Dehaene proposed in PNAS that the readiness potential may reflect spontaneous, random fluctuations in neural activity that happen to cross a threshold, not a hidden decision being prepared. If so, the early build-up is not evidence of an unconscious choice at all.

Other critics pointed to the method. Dennett said the clock-watching task involves shifts of attention and ambiguity about timing. Alfred Mele argued that the felt urge to move is vague, which makes it hard to compare with a brain signal. Studies by Banks and Isham in 2009 found that reported times of intention shifted depending on a tone presented after the action, suggesting people partly reconstruct their sense of timing. In 2010 Miller and Trevena reported a similar signal whether or not volunteers went on to tap. A 2021 meta-analysis judged the readiness-potential effect uncertain and based on few studies.

There is a scope problem as well. These experiments use trivial, arbitrary movements over a few seconds. Real decisions, such as taking a job or ending a relationship, involve deliberation over hours or years. A 2016 study in PNAS reported a point of no return about 200 milliseconds before movement, after which vetoing was not possible, so even the veto idea has been questioned.

One summary of this literature notes that it is very unlikely a single study could disprove all definitions of free will. That seems right.

Does it matter whether people believe in free will?

Some psychologists have asked whether belief in free will affects conduct. A 2008 study by Kathleen Vohs and Jonathan Schooler reported that people who read a passage denying free will cheated more on a later task. Later studies have reported contradictory findings, so the effect is far from established.

Philosophers also argue about responsibility. Hard incompatibilists suggest that society could keep institutions such as law and education while dropping retribution. Compatibilists say responsibility depends on the capacities that compatibilism describes, so nothing needs to be given up. These are normative arguments, not experimental results.

What do philosophers actually think?

The 2020 PhilPapers Survey asked professional philosophers. Of 1,758 respondents who answered, about 59 percent chose compatibilism, 19 percent libertarianism and 11 percent no free will, with the remainder choosing other options. Respondents could select more than one, as the survey’s organiser David Chalmers noted, so a no-free-will compatibilist could tick both boxes.

This is a snapshot of opinion among academics, not a measurement of truth. Still, it shows that the most common view in the field is neither that free will is an illusion nor that it is a mysterious power, but that it is a real and useful capacity compatible with a lawful world.

Common questions

Has neuroscience disproved free will?

No. Experiments show that brain activity precedes reported awareness of deciding in some simple tasks, and that reports of timing can be biased. They do not settle the philosophical question, and the interpretation of the key signal is disputed.

What is compatibilism in plain terms?

It is the view that you can be free in the sense that matters, acting on your own reasons without being forced, even if everything is caused. Free will, on this view, is about how a decision is made, not about escaping causation.

If the universe is random, is that free will?

Not by itself. A random event is not something you control. This is the standard objection to libertarian views that rely on indeterminism.

Is the readiness potential a decision?

That is exactly what is debated. The traditional reading treats it as an unconscious preparation to act. The 2012 alternative treats it as background neural noise that sometimes crosses a threshold.

Why do people still feel free?

The feeling of choosing is real as an experience. Whether it tracks an underlying causal power is a separate matter, and this question has no agreed answer.

What to remember

The facts are modest. Brain activity linked to an action can start before people report deciding, but the meaning of that activity is disputed, and the experiments cover only simple, short-term choices. The philosophy is where most of the weight sits: the answer depends on how free will is defined, and a majority of surveyed philosophers hold a compatibilist view.

Anyone who claims science has proved that we have no free will, or proved that we do, is claiming more than the evidence supports.

Further reading

A 2023 book arguing the hard-determinist case, useful as a counterpoint to the compatibilist majority. See it on Amazon (affiliate link)

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