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Neuroscience Refutes Free Will? Addressing an Objection

Functional magnetic resonance imaging (fMRI) is not as good as Libet’s methods for assessing real-time effects

In reply to a post in which I pointed out that neuroscience strongly supports the reality of free will, commenter AaronS1978 makes a point at Uncommon Descent:

First Michael Egnor is wrong about there being no brain wave activity with free won’t Patrick Haggard in 2014 discovered accidotal brain waves to free won’t

I feel he kind of makes declarations, I understand his position philosophically and I do agree with a lot of it, but saying there is no activity before free won’t and saying it’s immaterial is incorrect

Furthermore why wouldn’t there be brain activity when exercising your will?

Wouldn’t that just mean that your soul was using your brain?

Isn’t consciousness and conscious experience (hard problem of the consciousness) inherently immaterial? This experience is almost inherently immaterial yet is has a direct material component. Nobody as of yet has answered this question hence why it’s hard, but it’s hard because we can’t find direct neural correlates to experience per say and this experience includes those Appetites he speaks of

I’ll get to Haggard et al’s research shortly. but first let’s discuss AaronS1978’s point about the complexity inherent to neuroscience of free will. He’s right. The neuroscience of free will faces enormously complex problems.

We have two kinds of appetites (the term that describes our inclinations and decisions to act): sensitive appetite and rational appetite. Sensitive appetite is appetite motivated by particular things like perceptions of objects, images in imagination, emotions, etc.

Included in sensitive appetite is lust, anger, fear, joy, etc. These desires are not will, and they are not free. They are not free because they are driven by material states of our brain—an injection of adrenaline can make us angry or afraid, and an aphrodisiac can make us lustful.

For all animals except man, all appetites are sensitive appetites. Animals have no free will. Sensitive appetites are not what is meant by free will.

Free will is appetite based on abstract reason. By reason, I mean the ability to contemplate abstract concepts without particular material objects in mind. I can contemplate morality as an abstraction just as I can contemplate logic or mathematics without any particular physical object in mind. Rational appetite that arises from abstract rational thought is what I mean by free will. I mean it is free in the sense that it is not caused by matter. Free will—free rational appetite—is free because it is immaterial. Intellect and will are immaterial powers of the human soul.

This understanding of appetites is the classical understanding of Plato, Aristotle, and Aquinas and it makes beautiful sense of human motivation. We are beset by sensitive appetites—temptations that arise involuntarily from our brain. Yet we, as human beings, retain rational appetites—desires and decisions based on reason. It is these rational appetites that are our free will. Our moral life is a balance between sensitive appetites which we do not directly control, and our free will, which we do control. We are beset continuously by temptations, and although tempted we are free to choose.

So how can we test this classical understanding of human free will using neuroscience? In this respect, commenter AaronS1978 is right: It is a difficult and subtle question. Only two researchers have addressed this real question of free will with any rigor.

The first was Wilder Penfield, who was the first neurosurgeon to systematically operate on the brains of people while they were awake (he used local anesthetics). He found that he could stimulate all sorts of things that we would call the sensitive appetites—anger, joy, lust etc. But he could not stimulate rational will. He also noted that epileptic seizures—spontaneous abnormal electrical discharges from the brain—could evoke sensitive appetites but not rational appetite. Seizures never evoke the will—we don’t have morality seizures or seizures that make us do mathematics or logic. Seizures only evoke physical things like movements or sensations or passions. Penfield concluded that the will (and the intellect) are immaterial powers of the soul. In this sense of freedom from materiality, the will is free.

The second was Benjamin Libet, who studied volunteers making choices to push buttons. When Libet measured the brain waves of volunteers, he found that, while the unconscious predisposition to push a button was associated with a specific brain wave, a veto of the decision was not associated with any new brain wave. That is, it seemed that we are tempted to do things based on material processes in our brains but we retain the immaterial ability to veto (or accept) compliance with the temptation. Libet interpreted his research as supportive of free will.

Many neuroscientists have attempted to replicate the Libet-type button-pushing experiments but nearly all of them have used fMRI instead of measuring brain waves. That is the research Haggard and his collaborators have done, to which AaronS1978 referred.

But fMRI is worthless in the neuroscience of free will. To understand why, note that fMRI has very poor temporal resolution. fMRI measures changes in blood flow in the brain in response to activity of neurons, and these changes lag neuronal activity by at least several seconds. Peak fMRI response seems to occur about 6 seconds after neuronal activity occurs, and may persist for up to 40 seconds. fMRI is best though-of as a long-time exposure of brain activity rather than a snapshot, which the measurement of brain waves (EEG) provides. Libet’s experiments were using brain waves and the time interval in which the immaterial “free won’t veto” occurred was on the order of 200 milliseconds—1/5 of a second. fMRI is at least an order of magnitude too insensitive to timing to record this level of change, which is why it is worthless in the neuroscientific study of free will.

Libet’s work was the best—and essentially only—meaningful neuroscientific exploration of free will associated with timing of decisions to perform simple acts and his research clearly supports the reality of free will. There is no doubt that these issues are subtle and complex—after all, both sensitive appetite and rational appetite ordinarily occur together. We have emotions (sensitive appetite) associated with reasoning (rational appetite) and it is difficult to tease out the neural correlates of both. But unfortunately, nearly all neuroscientists (except Libet) have tried to tease out these questions using fMRI which, because of poor temporal resolution, is worthless in assessing the reality of free will.

The most convincing neuroscientific evidence for free will is Penfield’s conclusion that abstract will has never been evoked by brain stimulation or seizure. That’s true. No seizure documented in medical history has involved abstract reasoning or rational will as part of the seizure itself. There are no morality seizures, no logic seizures, no mathematics seizures. Seizures can be complex—there is a whole category of seizures called complex partial seizures that entail walking and a host of complex movements. But there are no free will seizures—no seizures that entail motives based on reason.

If the human will is not free, and is driven entirely by brain processes, then some seizures—which are spontaneous brain processes—should evoke the will. But seizures never invoke the will, and the obvious interpretation is that the will is not caused by brain processes. In that sense, the will is free.


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Michael Egnor

Senior Fellow, Center for Natural & Artificial Intelligence
Michael R. Egnor, MD, is a Professor of Neurosurgery and Pediatrics at State University of New York, Stony Brook, has served as the Director of Pediatric Neurosurgery, and award-winning brain surgeon. He was named one of New York’s best doctors by the New York Magazine in 2005. He received his medical education at Columbia University College of Physicians and Surgeons and completed his residency at Jackson Memorial Hospital. His research on hydrocephalus has been published in journals including Journal of Neurosurgery, Pediatrics, and Cerebrospinal Fluid Research. He is on the Scientific Advisory Board of the Hydrocephalus Association in the United States and has lectured extensively throughout the United States and Europe.

Neuroscience Refutes Free Will? Addressing an Objection