Stephen Morse and the Neuroscience of Law

It seems that recent research in neuroscience is challenging traditional conceptions of free will and legal responsibility. Neuroscience shows that the brain is a physical entity governed by natural causes and is thus just as deterministic as the rest of the physical world. Neuroscience also shows how the brain determines the mind. It seems to follow that the mind's thoughts and choices are determined. But if that is so, then it seems that free will is an illusion, because no one is really responsible for his or her choices. This would deny the traditional understanding of responsibility in morality and law. People cannot be held morally or legally responsible for their choices, because they can always say, My brain made me do it!

If this were true, it would be a social catastrophe unprecedented in human history, because it would abolish the psychological foundations of our moral and legal systems. The fear of such a catastrophe motivates much of the fear of modern biological explanations of human nature. One can see that fear, for example, in the writing of intelligent design creationists like John West. (West has been the subject of many of my posts on this blog.) These folks assume that we cannot hold people morally and legally responsible for their behavior unless we invoke the idea that human beings have been created in God's image with a spiritual soul that cannot be explained as a product of natural evolutionary causes, because only such a supernatural soul can exercise free will in acting as an uncaused cause that transcends the realm of natural causes as studied by science.

But as I have argued in Darwinian Natural Right, in Darwinian Conservatism, and on this blog, this fear is unwarranted, because biological explanations of human nature in general and of the human brain in particular are fully compatible with traditional conceptions of moral and legal responsibility.

I agree with Jonathan Edwards, David Hume, and others who argue that moral responsibility and natural causation are compatible. But to see this compatibility, we must reject the idea of "free will" as uncaused cause. Whatever comes into existence must have a cause. Only what is self-existent from eternity--God--could be uncaused or self-determined. The commonsense notion of liberty is power to act as one chooses regardless of the cause of the choice. Human freedom of choice is not freedom from nature but a natural freedom to deliberate about our natural desires so that we can organize and manage our desires through habituation and reflection to conform to some conception of a whole life well lived. This is how Aristotle understood moral choice.

Similarly, Darwin believed that "every action whatever is the effect of a motive," and therefore he doubted the existence of "free will." Our motives arise from a complex interaction of innate temperament, individual experience, social learning, and external conditions. Still, although we are not absolutely free of the causal regularities of nature, Darwin believed, we are morally responsible for our actions because of our uniquely human capacity for reflecting on our motives and circumstances and acting in the light of those reflections. "A moral being is one who is capable of reflecting on his past actions and their motives--of approving of some and disapproving of others; and the fact that man is the one being who certainly deserves this designation is the greatest of all distinctions between him and the lower animals."

If we understand moral responsibility in this way, and see this as the conception of responsibility assumed in the law, then neuroscientific research on the natural causality of the brain is no threat to moral and legal responsibility. Stephen Morse--a law professor at the University of Pennsylvania Law School who specializes in psychology and law--has laid out the case for this conclusion based on a "compatibilist" view of moral choice. He has done this in "New Neuroscience, Old Problems," a paper published in two books--Neuroscience and the Law (2004), edited by Brent Garland, and Defining Right and Wrong in Brain Science (2007), edited by Walter Glannon, both published by Dana Press.

As Morse indicates, the "hard determinists" and the "metaphysical libertarians" agree that "free will" would require a "contra-causal freedom." But while the determinists deny there is such a thing. The libertarians affirm its existence as an uncaused cause beyond natural causality. If we had to choose between these two positions, neuroscience would favor the determinists.

But Morse rightly argues that the law's conception of responsibility does not require a "contra-causal freedom." It requires only that human beings have sufficient practical rationality to understand their choices and to act on their deliberate decisions. When rationality is so diminished that someone cannot understand or act on his choices--a child or someone who is insane, for example--then we excuse their behavior and do not hold them fully responsible for their actions. But this conception of moral and legal responsibility as based on the capacity for practical deliberation or rationality does not require any transcendence of natural causality.

Under the "compatibilist" conception of responsibility that Morse, Darwin, and I defend, research in neuroscience can have some interesting implications for law, but it poses no fundamental challenge to the traditional understanding of legal responsibility. Neuroscience can tell us a lot about the natural causes in the brain that predispose human beings in one direction or another. But this does not deny what Darwin recognized as the uniqueness of a human beings as moral beings capable of reflecting on their circumstances and acting on the basis of past experience and future expectations. This is not free will as an uncaused cause, but it is the natural freedom that human beings have as a product of their evolved nature.