A family man suddenly turns into a pedophile… and starts collecting child pornography, prostituting children, harassing his own niece, among others. Condemned for his actions, he had a choice between imprisonment or a rehabilitation program for sex addicts and, of course, he opted for the program . . . but he proved unable to control his impulses. The night before his arrest, he was admitted to a hospital emergency room and asked for an MRI of his brain. The result: a sizable tumor located in a part of the brain responsible for regulating social behavior, which in turn includes controlling sexual impulses. Soon after the tumor removal surgery, the pedophile behavior disappeared. Some time later, the inappropriate behavior resurfaced and a new MRI confirmed the recurrence of the cancer. So the question remains: where is free will?

This man as well as the classic Phineas Gage and countless others of brain damage that directly affect social behavior contradict the almost universal belief in free will. And questioning its existence shakes the entire infrastructure of our society, from the legislative system to the judiciary, all based on free will.

Whether you believe it or not, your brain decides what you’re going to decide, half a millisecond before you think you’re deciding for yourself, that is, your mind receives the decision that comes from your brain and not the other way around.

But what’s the problem with accepting that we have virtually no free will? Well… scientific evidence indicates that people who don’t believe in free will are more aggressive, less productive, more anti-social, and more likely to be dishonest. In other words, not believing in free will affects the brain functioning which in turn modifies the attitudes that will be performed by the owner of that brain.

Let’s give an example. Two researchers decided to team up to test how motivating a belief in determinism or free will can affect human behavior. They divided the volunteers into two groups. In one group, people read texts that endorsed determinism while in the other group, people read texts that endorsed free will. Subsequently, both groups performed activities where they were exposed to the chance of cheating (acquiring answers from the computer while being instructed to solve the problem themselves). What happened? Volunteers induced to believe in determinism circumvented the test while volunteers induced to believe in free will did not circumvent the test. Were they aware of why they decided to circumvent the test or not? No way! Their brains were influenced by reading the text and their minds acted upon this induction without even realizing it… This study is just one among dozens of others who reach the same conclusion: free will is a necessary illusion.

PS: This text was based on the chapter Free Will: A Grand Illusion do livro Impulse: Why we do what we do without knowing why we do it escrito por David Lewis (2013, pp. 198-204) e no artigo The Value of Believing in Free Will: Encouraging a belief in determinism increases cheating escrito por Kathleen D. Vohs e Jonathan W Schooler (2008).