Research in neuroscience has revealed a startling fact that revolutionizes much of what we humans have previously taken for granted about our interactions with the world outside our heads: Our consciousness is really not in charge of our behavior.
Laboratory experiments show that before we become aware of making a decision, our brains have already laid the groundwork for it. In a recent book, Subliminal: How Your Unconscious Mind Rules Your Behavior, physicist Leonard Mlodinow reviews a wide range of psychological experiments that demonstrate the dominant role the unconscious plays in our behavior. This recognition challenges fundamental assumptions about free will and the associated religious teachings about sin and redemption, as well as our judicial concepts of responsibility and punishment. If our brains are making our decisions for us subconsciously, how can we be responsible for our actions? How can our legal system punish criminals or God punish sinners who aren't in full control of their decision-making processes?
Is free will an illusion? In his recent book titled Free Will, neuroscientist Sam Harris pulls no punches. He tells us in no uncertain terms: "Free will is an illusion." We don't exist as immaterial conscious controllers, but are instead entirely physical beings whose decisions and behaviors are the fully caused products of the brain and body.
Philosophers identify several different positions on the question of free will. Incompatibilists hold that free will is incompatible with determinism, the idea that our behavior is fully determined by antecedent causes such as fate, acts of God, or laws of nature. These split into two camps. Libertarians hold that we have free will since humans transcend cause and effect in ways that make us ultimately responsible. Determinists hold that we don't have free will because either determinism is true or indeterminism (randomness) doesn't give us control or responsibility. Both these groups are opposed by compatibilists, who argue that free will is compatible with determinism, or indeterminism for that matter.
What exactly is determinism? Two centuries ago, French physicist Pierre Laplace pointed out that, according to Newtonian mechanics, the motion of every particle in the universe can in principle be predicted from the knowledge of its position, momentum, and the forces acting on it. This is the Newtonian world machine. Since, as far as physics is concerned, we are all just particles, then this would seem to make free will an illusion indeed.
However, we now can say with considerable confidence that the universe is not a Newtonian world machine. The Heisenberg uncertainty principle of quantum mechanics showed that, deep down, nature is fundamentally indeterministic. But does quantum indeterminacy play an important role in the brain, and thus open a way for free will? Probably not, and here's why.
The moving parts of the brain are heavy by microscopic standards and move around at relatively high speeds because the brain is hot. Furthermore, the distances involved are large by these same microscopic standards. It is easy to demonstrate quantitatively that quantum effects in the brain are not significant. So, even though libertarians are correct that determinism is false at the microphysical, quantum level, the brain is for all practical purposes a deterministic Newtonian machine, so we don't have free will as they define it.
Although the brain is likely deterministic when it comes to the control of behavior, there's plenty of "pseudo-randomness" (as opposed to "pure" quantum randomness) in the thermal motions of our brains and in the environment that feeds us data. It's possible that this can provide sufficient uncertainty to give us the "feeling" of free will. Or, perhaps uncertainty plays no direct role and it is simply our lack of awareness about what causes our decisions that we interpret as being exempt from the causal laws of nature. Either way, this means that ultimately we do not have libertarian free will, even though we might be under the impression we do.
But here's some consolation. Even though at the quantum level there is no rigid determinism, the compatibilists are correct in viewing the operations of the brain as causal processes. They also make another good point when they argue that even if our thoughts and actions are the product of unconscious processes, they are still our thoughts and actions. In other words, "we" are not just our conscious minds, but rather the sum of both conscious and unconscious processes. While others can influence us, no one has access to all the data that went into the calculation except our unique selves. Another brain operating according to the same decision algorithms as ours would not necessarily come up with the same final decision since the lifetime experiences leading up to that point would be different.
So, although we don't have libertarian free will, if a decision is not controlled by forces outside ourselves, natural or supernatural, but by forces internal to our bodies, then that decision is ours. If you and I are not just some immaterial consciousness (or soul) but rather our physical brains and bodies, then it is still "we" who make our decisions. And after all, that's what the brain evolved to do, whatever role consciousness might play. And, therefore, it is "we" who are responsible for those decisions.
And that's what it all boils down to. Who cares whether we call an action "free will" or not? Calling it "free will" (as compatibilists do) is too confusing, since it suggests some form of dualism, supernatural or not; so let's call it "autonomy." The issue is: what is the moral and legal responsibility of an autonomous person, and how should society deal with wrongdoing?
Obviously, we cannot have a functioning society if we do not protect ourselves from people who are dangerous to others because of whatever it is inside their brains and nervous systems that makes them dangerous. Still, given that we don't have libertarian free will that sets us above causal laws, it would seem that our largely retributive moral and justice systems need to be re-evaluated, and maybe even drastically revamped.