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Free Will vs. Free Won't

Perhaps the most fundamental implication of 21st-century brain science is that a way may exist to evaluate free will. The logic goes like this: The brain determines the mind, and the brain is subject to all the rules of the physical world. The physical world is determined, so our brains must also be determined. If so, then we must ask: Are the thoughts that arise from the brain also determined? Is the free will we seem to experience just an illusion? And if free will is an illusion, must we revise our conception of what it means to be personally responsible for our actions?

This conjecture has haunted philosophers for decades. But with new imaging tools that show the human brain in action, these questions are being reexamined by neuroscientists and, increasingly, the legal world. Defense lawyers are looking for that one pixel in their client's brain scan that shows an abnormality - some sort of malfunction that would allow them to argue: "Harry didn't do it. His brain did it. Harry is not responsible for his actions."

At the same time, we must realize that even if the causation of an act (criminal or otherwise) is explainable in terms of brain function, that does not mean that the person who carries out the act is exculpable. Although brains can be viewed as more or less automatic devices, like clocks, we as people seem free to choose our own destiny. Is there a way to settle this dilemma?

A first step was taken in the 1980s by Benjamin Libet, now emeritus professor of physiology at the University of California at San Francisco. If the brain carries out its work before one becomes consciously aware of a thought, as most neuroscientists now accept as true, it would appear that the brain enables the mind. This idea underlies the neuroscience of determinism. Libet measured brain activity during voluntary hand movements. He found that between 500 and 1,000 milliseconds before we actually move our hand there is a wave of brain activity, called the readiness potential. Libet set out to determine the moment, somewhere in that 500 to 1,000 milliseconds, when we make the actual conscious decision to move our hand.

Libet found that the time between the onset of the readiness potential and the moment of conscious decision making was about 300 milliseconds. If the readiness potential of the brain is initiated before we are aware of making the decision to move our hand, then it would appear that our brains know our decisions before we become conscious of them.

This kind of evidence seems to indicate that free will is an illusion. But Libet argued that because the time from the onset of the readiness potential to the actual hand movement is about 500 milliseconds, and it takes 50 to 100 milliseconds for the neural signal to travel from the brain to the hand to actually make it move, then there are 100 millisecond left for the conscious self to either act on the unconscious decision or veto it. That, he said, is where free will arises - in the vetoing power. Neuroscientist Vilayanur Ramachandran of the University of California at San Diego, in an argument similar to 17th-century English philosopher John Locke's theory of free will, suggests that our conscious minds may not have free will but do have "free won't."

Closing paragraph:

Still, we would like to offer the following axiom: brains are automatic, rule-governed, determined devices, whereas people are personally responsible agents free to make their own decisions. Just as traffic is what happens when physically determined cars interact, responsibility is what happens when people interact. Brains are determined; people are free.

- excerpted from Neuroscience and the Law by M. Gazzaniga and M. Steven

Scientific American Mind, Vol. 16, No. 1