Get the FREE DIGITAL BOOK: The Case for Killer Robots
Mind Matters Reporting on Natural and Artificial Intelligence
Green wavy parrot is sitting on a white cage. The parrot looks out of the cage.

How a Neuroscientist Imaged Free Will (and “Free Won’t”)

At first, Libet thought that free will might not be real. Then he looked again…

In a recent podcast, “Free Will or Free Won’t?”, Robert J. Marks discussed free will, free won’t, predestination, and the brain with Dr. Michael Egnor. In this transcribed portion, they look at neuroscientist Benjamin Libet’s findings on free will.

A partial transcript follows:

02:02 | The research of Benjamin Libet (1916–2007)

Michael Egnor: Ben Libet was a neuroscientist at the University of California, San Francisco, for many years in the mid-twentieth century and he didn’t win the Nobel Prize but I thin he should have. He certainly is one of the most consequential neuroscientists of the twentieth century.

Libet’s fascination was with the relationship between thoughts and time. That is, he wanted to know what was happening inside the brain, timed as precisely as possible with activity of the brain. So, at the moment you think something, what is the brain doing? He wrote a book for the lay press called Mind Time: The Temporal Factor in Consciousness (2005), a fairly nice synopsis of his research…

He did many different kinds of experiments looking at brain waves and thoughts and his most famous experiment was on the question of free will. He asked a whole bunch of normal volunteers to sit at a desk and he had a button in front of them that they could push and he had a clock in front of them. They could look at the clock and within a few milliseconds, they could time a thought that came into their head.

The clock had a sweep second hand; I think it was on an oscilloscope. They could say that they had this thought at exactly this time within a few milliseconds. And he also attached electrodes to their scalps so he could record the electrical activity in their brain.

And he asked them. Just sit there at the desk and whenever you decide to push the button, look at the moment you decide to push the button on the clock and then push the button. And he would record their brain waves, synchronized in time with the clock and with the button-pushing. So he could kind of tell what was going on in the brain, corresponding to their thought and to the pushing of the button.

And what he found was that about half a second before they decided to push the button, there was a spike in the brain wave activity corresponding to that thought. And again, he found that it happened before the thought, before the decision. So he initially thought that that argued against free will. It almost seemed like the brain was generating the thought and the person didn’t really have any control over it. It was just the physiology of the brain that made the thought happen.

So he said that free will might not be real. It might just be driven by brain chemistry.

Note: This image is Figure 1 from Karim Fifel, “Readiness Potential and Neuronal Determinism: New Insights on Libet Experiment”, Journal of Neuroscience (24 January 2018, 38 (4) 784-786; DOI: It depicts three types of brain activity which build up before voluntary action: the readiness potential, an event-related potential measured by EEG; a ramp-up of single-neuron firing rates; and a buildup of neurotransmitter levels. (CC BY-SA 4.0 24 January 2018)

Michael Egnor: But then, being a really good scientist, he decided to look at it in a little more depth. So he asked the people, when you make a decision to push the button, immediately veto the decision. So, sit there at the desk, say “Hey, I’m going to push this button” and then say “No, maybe I won’t push the button.” And then don’t push it. So he looked at the vetoes. And what he found was, when you made a decision to push the button, you still had the brain wave that preceded the decision by half a second. But when you decided to veto pushing the button, there was no new brain wave at all. It was silent in terms of brain waves.

Robert J. Marks: Interesting.

Michael Egnor: But you did make the decision to veto. So he said that it wasn’t so much that you have free will but you have free won’t. That is, you have the ability to decide whether or not you are going to comply with what your brain is urging you to do. And that compliance is not material. It’s not a brain wave. It’s immaterial. And he said, that’s the soul. That’s free will.

So he thought that he really had demonstrated scientifically that we have an immaterial power to override our, you might say, material temptations. He said that this corresponds rather remarkably to the traditional religious understanding of temptation and original sin. He said that we have a constant bombardment urging us to do things and we have the free will to override that. And the free will is not from the brain; it’s a spiritual thing…

Show Notes

00:40 | Introducing Dr. Michael Egnor, Professor of Neurosurgery and Pediatrics at State University of New York, Stony Brook
01:04 | Free will vs. predestination
01:49 | The research of Benjamin Libet
07:07 | Overcoming addictions
08:01 | Rewiring your brain
09:13 | Hebb’s Law
10:00 | The misrepresentation of Benjamin Libet’s experiments
11:44 | Reproducing Benjamin Libet’s experiments

Next: How Libet’s work on free will has been misrepresented

Further reading on free will and free won’t:

Can free will really be a scientific idea? (Eric Holloway) Yes, if we look at it from the perspective of information theory

Why do atheists still claim that free will can’t exist? Sam Harris reduces everything to physics but then ignores quantum non-determinism (Eric Holloway)

Was famous old evidence against free will just debunked? The pattern that was thought to prove free will an illusion may have been noise


Younger thinkers now argue that free will is real. The laws of physics do not rule it out, they say.

Also by Dr. Michael Egnor on free will:

Can physics prove there is no free will?

Does “alien hand syndrome” show that we don’t really have free will?

How can mere products of nature have free will?

Does brain stimulation research challenge free will?

Is free will a dangerous myth?


But is determinism true?

Mind Matters News

Breaking and noteworthy news from the exciting world of natural and artificial intelligence at

How a Neuroscientist Imaged Free Will (and “Free Won’t”)