Sam Harris goes on to say:
It is safe to say that no one was ever moved to entertain the existence of free will because it holds great promise as an abstract idea. The endurance of this notion is attributable to the fact that most of us feel that we freely author our own thoughts and actions (however difficult it may be to make sense of this in logical or scientific terms). Thus the idea of free will emerges from a felt experience. It is, however, very easy to lose sight of this psychological truth once we begin talking philosophy.
In the philosophical literature, one finds three main approaches to the problem: determinism, libertarianism, and compatibilism. Both determinism and libertarianism hold that if our behavior is fully determined by background causes, free will is an illusion. (For this reason they are both referred to as “incompatibilist” views.) Determinists believe that we live in such a world, while libertarians (no relation to the political philosophy that goes by this name) imagine that human agency must magically rise above the plane of physical causation. Libertarians sometimes invoke a metaphysical entity, such as a soul, as the vehicle for our freely acting wills. Compatibilists, however, claim that determinists and libertarians are both confused and that free will is compatible with the truth of determinism.
Today, the only philosophically respectable way to endorse free will is to be a compatibilist— because we know that determinism, in every sense relevant to human behavior, is true. Unconscious neural events determine our thoughts and actions— and are themselves determined by prior causes of which we are subjectively unaware. However, the “free will” that compatibilists defend is not the free will that most people feel they have.
Compatibilists generally claim that a person is free as long as he is free from any outer or inner compulsions that would prevent him from acting on his actual desires and intentions. If you want a second scoop of ice cream and no one is forcing you to eat it, then eating a second scoop is fully demonstrative of your freedom of will. The truth, however, is that people claim greater autonomy than this. Our moral intuitions and sense of personal agency are anchored to a felt sense that we are the conscious source of our thoughts and actions. When deciding whom to marry or which book to read, we do not feel compelled by prior events over which we have no control.
The freedom that we presume for ourselves and readily attribute to others is felt to slip the influence of impersonal background causes. And the moment we see that such causes are fully effective— as any detailed account of the neurophysiology of human thought and behavior would reveal— we can no longer locate a plausible hook upon which to hang our conventional notions of personal responsibility. 5 What does it mean to say that rapists and murderers commit their crimes of their own free will? If this statement means anything, it must be that they could have behaved differently— not on the basis of random influences over which they have no control, but because they, as conscious agents, were free to think and act in other ways. To say that they were free not to rape and murder is to say that they could have resisted the impulse to do so (or could have avoided feeling such an impulse altogether)— with the universe, including their brains, in precisely the same state it was in at the moment they committed their crimes. Assuming that violent criminals have such freedom, we reflexively blame them for their actions. But without it, the place for our blame suddenly vanishes, and even the most terrifying sociopaths begin to seem like victims themselves. The moment we catch sight of the stream of causes that precede their conscious decisions, reaching back into childhood and beyond, their culpability begins to disappear.