Is free will an illusion? Recent scientific arguments for an affirmative answer have a simple structure. First, data are offered in support of some striking empirical proposition—for example, that conscious intentions never play any role in producing corresponding actions. Then this proposition is linked to a statement about what free will means to yield the conclusion that it does not exist.
In my book Effective Intentions: The Power of Conscious Will (Oxford University Press, 2009), I explain why the data do not justify such arguments. Sometimes I am told that even if I am correct, I overlook the best scientific argument for the nonexistence of free will. This claim, in a nutshell, has two parts: Free will depends on the activity of nonphysical minds or souls, and scientists have shown that something physical—the brain—is doing all the work.
Jerry A. Coyne
Alfred R. Mele
Michael S. Gazzaniga
Owen D. Jones
As the majority of philosophers understand the concept, free will doesn't depend at all on the existence of nonphysical minds or souls. But philosophers don't own this expression. If anyone owns it, people in general do. So I conducted some simple studies.
In one, I invited participants to imagine a scenario in which scientists had proved that everything in the universe is physical and that what we refer to as a "mind" is actually a brain at work. In this scenario, a man sees a $20 bill fall from a stranger's pocket, considers returning it, and decides to keep it. Asked whether he had free will when he made that decision, 73 percent answer yes. This study suggests that a majority of people do not see having a nonphysical mind or soul as a requirement for free will.
If free will does not depend on souls, what is the scientific evidence that it is an illusion? I'll briefly discuss just one study. Chun Siong Soon and colleagues, in a 2008 Nature Neuroscience article, report the results of an experiment in which participants were asked to make simple decisions while their brain activity was measured using functional magnetic resonance imaging, or fMRI. The options were always two buttons, and nothing hinged on which was pressed. Soon and coauthors write: "We found that two brain regions encoded with high accuracy whether the subject was about to choose the left or right response prior to the conscious decision," noting that "the predictive neural information ... preceded the conscious motor decision by up to 10 seconds." The science writer Elsa Youngsteadt represented these results as suggesting that "the unconscious brain calls the shots, making free will an illusory afterthought."
In this study, however, the predictions are accurate only 60 percent of the time. Using a coin, I can predict with 50-percent accuracy which button a participant will press next. And if the person agrees not to press a button for a minute (or an hour), I can make my predictions a minute (or an hour) in advance. I come out 10 points worse in accuracy, but I win big in terms of time.
So what is indicated by the neural activity that Soon and colleagues measured? My money is on a slight unconscious bias toward a particular button—a bias that may give the participant about a 60-percent chance of pressing that button next.
Given such flimsy evidence, I do not recommend betting the farm on the nonexistence of free will.
Alfred R. Mele is a professor of philosophy at Florida State University. He is the director of Big Questions in Free Will, an investigation of the science, philosophy, and theology of free will, supported by a $4.4-million grant from the John Templeton Foundation.