Skip to main content

How a Flawed Experiment “Proved” That Free Will Doesn’t Exist

It did no such thing—but the result has become conventional wisdom nevertheless

Credit:

Getty Images

This article was published in Scientific American’s former blog network and reflects the views of the author, not necessarily those of Scientific American


In the second half of the 19th century, scientific discoveries—in particular, Darwin’s theory of evolution—meant that Christian beliefs were no longer feasible as a way of explaining the world. The authority of the Bible as an explanatory text was fatally damaged. The new findings of science could be utilized to provide an alternative conceptual system to make sense of the world—a system that insisted that nothing existed apart from basic particles of matter, and that all phenomena could be explained in terms of the organization and the interaction of these particles.

One of the most fervent of late 19th century materialists, T.H. Huxley, described human beings as “conscious automata” with no free will. As he explained in 1874, “Volitions do not enter into the chain of causation…. The feeling that we call volition is not the cause of a voluntary act, but the symbol of that state of the brain which is the immediate cause."

This was a very early formulation of an idea that has become commonplace amongst modern scientists and philosophers who hold similar materialist views: that free will is an illusion. According to Daniel Wegner, for instance, “The experience of willing an act arises from interpreting one’s thought as the cause of the act.” In other words, our sense of making choices or decisions is just an awareness of what the brain has already decided for us. When we become aware of the brain’s actions, we think about them and falsely conclude that our intentions have caused them. You could compare it to a king who believes he is making all his own decisions, but is constantly being manipulated by his advisors and officials, who whisper in his ear and plant ideas in his head. 


On supporting science journalism

If you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.


Many people believe that evidence for a lack of free will was found when, in the 1980s, scientist Benjamin Libet conducted experiments that seemed to show that the brain “registers” the decision to make movements before a person consciously decides to move. In Libet’s experiments, participants were asked to perform a simple task such as pressing a button or flexing their wrist. Sitting in front of a timer, they were asked to note the moment at which they were consciously aware of the decision to move, while EEG electrodes attached to their head monitored their brain activity.

Libet showed consistently that there was unconscious brain activity associated with the action—a change in EEG signals that Libet called “readiness potential”—for an average of half a second before the participants were aware of the decision to move. This experiment appears to offer evidence of Wegner’s view that decisions are first made by the brain, and there is a delay before we become conscious of them—at which point we attribute our own conscious intention to the act.         

However, if we look more closely, Libet’s experiment is full of problematic issues. For example, it relies on the participants’ own recording of when they feel the intention to move. One issue here is that there may be a delay between the impulse to act and their recording of it—after all, this means shifting their attention from their own intention to the clock. In addition, it is debatable whether people are able to accurately record the moment of their decision to move. Our subjective awareness of decisions is very unreliable. If you try the experiment yourself—and you can do it right now, just by holding out your own arm, and deciding at some point to flex your wrist—you’ll become aware that it’s difficult to pinpoint the moment at which you make the decision. 

An even more serious issue with the experiment is that it is by no means clear that the electrical activity of the “readiness potential” is related to the decision to move, and to the actual movement. Some researchers have suggested that the readiness potential could just relate to the act of paying attention to the wrist or a button, rather the decision to move. Others have suggested that it only reflects the expectation of some kind of movement, rather being related to a specific moment. In a modified version of Libet’s experiment (in which participants were asked to press one of two buttons in response to images on a computer screen), participants showed “readiness potential” even before the images came up on the screen, suggesting that it was not related to deciding which button to press. 

Still others have suggested that the area of the brain where the "readiness potential" occurs—the supplementary motor area, or SMA—is usually associated with imagining movements rather than actually performing them. The experience of willing is usually associated with other areas of the brain (the parietal areas). And finally, in another modified version of Libet’s experiment, participants showed readiness potential even when they made a decision not to move, which again casts doubt on the assumption that the readiness potential is actually registering the brain’s “decision” to move. 

A further, more subtle, issue has been suggested by psychiatrist and philosopher Iain McGilchrist. Libet's experiment seems to assume that the act of volition consists of clear-cut decisions, made by a conscious, rational mind. But McGilchrist points out that decisions are often made in a more fuzzy, ambiguous way. They can be made on a partly intuitive, impulsive level, without clear conscious awareness. But this doesn't necessarily mean that you haven't made the decision.

As McGilchrist puts it, Libet’s apparent findings are only problematic "if one imagines that, for me to decide something, I have to have willed it with the conscious part of my mind. Perhaps my unconscious is every bit as much 'me.'" Why shouldn't your will be associated with deeper, less conscious areas of your mind (which are still you)? You might sense this if, while trying Libet’s experiment, you find your wrist just seeming to move of its own accord. You feel that you have somehow made the decision, even if not wholly consciously. 

Because of issues such as these—and others that I don’t have space to mention—it seems strange that such a flawed experiment has become so influential, and has been (mis)used so frequently as evidence against the idea of free will. You might ask: why are so many intellectuals so intent on proving that they have no free will? (As the philosopher Alfred North Whitehead pointed out ironically, “Scientists animated by the purpose of proving themselves purposeless constitute an interesting subject for study.”)

This is probably because the nonexistence of free will seems a logical extension of some of the primary assumptions of the materialist paradigm—such as the idea that our sense of self is an illusion, and that consciousness and mental activity are reducible to neurological activity. However, as I suggest in my book Spiritual Science, it is entirely possible that these assumptions are false. The mind may be more than just a shadow of the brain, and free will may not be an illusion but an invaluable human attribute, which can be cultivated and whose development makes our lives more meaningful and purposeful.