'You Can't See Why on an fMRI'

What science can, and can't, tell us about the insanity defense

Brian Doherty from the July 2007 issue

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But metaphysical intangibles such as choice, intention, and judgment also, by universal human experience, affect chemicals in the brain. The conscious mind seems to itself cause activity in the physical organ from which it emerges. Why do sad songs or stories make us feel sad? Chemicals moving hither and yon influence and perhaps in some sense cause the felt emotion of sadness—but what makes them take action when they do? Why does adrenaline create edgy nervousness in a person about to speak before a crowd?

Purpose, intention, and judgment are so built into our felt experience that we cannot eliminate them from our consideration of human action, no matter how hard we try or what our metaphysical presumptions and scientific beliefs might be. As the Supreme Court acknowledged in Clark, the mind-brain perplexity needs much more scientific work before its study can be of dispositive use to the law.

Even if we had certain answers to these big, complicated questions of free will vs. determinism, or understood the precise neurological cause of mental problems, that wouldn’t necessarily dictate how the legal system should deal with those diagnosed as mentally ill. Some physical determinists have concluded that neuroscience cannot tell us whether we should hold people legally responsible for their actions.

The Dartmouth neuroscientist Michael Gazzaniga, author of The Ethical Brain and a proponent of a fully deterministic “brain-based philosophy of life,” told U.S. News and World Report in 2005 that he has never believed in the insanity defense. “One of the reasons,” he said, “is, if you look at schizophrenics, for example, their rate of violent behavior is not above that of the normal population, especially when they’re on their medication. So, if that’s true, how can you use that as a defense, that they’re doing something because they’re insane?” Personal responsibility, he explained, “has to do with the fact that people follow rules because they’re in a social group, and people with these various kinds of disorders can still follow those rules.”

Harvard’s Pinker figures that we can simultaneously believe in a fully caused human being and an ethical system that holds people responsible for their actions by imagining ethics as a “game” that it is useful for us to play for social purposes. In How the Mind Works, he writes that “the ethics game treats people as equivalent, sentient, rational, free-willed agents, and its rules are the calculus that assigns moral value to behavior through the behavior’s inherent nature or its consequences. Free will is an idealization of human beings that makes the ethics game playable.” The results of that game, he concludes, “can be sound and useful even though the world, as seen by science, does not really have uncaused events.”

Understanding Why
Juries and judges need to know what happened and why. As the Yates and Clark cases illustrate, psychiatry and neuroscience are not much help in answering those questions, despite the constant promise that a deeper and more expansive understanding of the relationship between brain and mind is just around the corner.

The closest we can come to knowing why Andrea Yates drowned her children or why Eric Clark shot a police officer is that they, or their neurons, chose to do it. Whether that choosing arose from irreducible free will or was merely an illusion, an outcome inevitable since one particle bumped into another during the Big Bang, remains unknown for now, despite anything a psychiatrist or neuroscientist might theorize.

Phillip Resnick, one of the leading witnesses in Andrea Yates’ defense, certainly believes in the value of expert psychiatric testimony in court. He testified that delusions caused by postpartum psychosis qualified Yates for the insanity defense under the Texas standard. But while he completely disagrees with those who think Yates was guilty in any normal sense of the word for her killing her children, his reasons have nothing to do with fMRIs or other high-tech windows to the brain.

He drew his conclusions the old-fashioned way, a way that doesn’t necessarily require a medical expert: by observing Yates and by talking to her and to people who knew her. He believed, from such evidence, that she was in the grip of psychotic delusions when she killed her kids, delusions that made her think that drowning them was in fact the right thing to do to save their souls.

Resnick’s belief convinced the second jury, without any recourse to objective neuroscience and its promises to help us understand exactly what in our brains makes us think, feel, and act as we do. Even in the 21st century, our ability to make those kinds of legal and moral judgments remains largely untouched by purely objective science. To make the judgments about human beings and their behavior that courts need to make, Resnick says, “You need to understand why. And you can’t see why on an fMRI.”

Senior Editor Brian Doherty is the author of This Is Burning Man (BenBella Books) and Radicals for Capitalism (PublicAffairs).

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