Good Question

If a brain tumor leads a father to molest his stepdaughter (an actual case), can he be held morally or legally responsible for his actions?

A forty-year-old Virginia father and teacher led a fairly normal heterosexual sex life until 2000, when he began collecting child pornography and, eventually, propositioned his stepdaughter. After being convicted of child molestation, he began experiencing headaches and a loss of coordination, leading to a diagnosis of a brain tumor. When the tumor was removed, his problematic behavior disappeared. He was eventually allowed to go home to his family. Several months later, the tumor returned, and so did his unusual behavior.

Many people conclude that this man was not fully responsible for his misconduct. I agree, but this judgment illustrates a conflict. All desires and actions are driven by various brain processes. Why is an individual responsible when a “normal” brain condition causes an act but not when a tumor causes an act?

Complicating the issue is the role of conscious will and its bearing on responsibility. In both law and morals, we normally excuse people whose acts are not caused by their conscious choices, such as sleepwalkers. The question is whether the excuse granted to sleepwalkers really applies to us all more often than we think. Surprisingly, recent research suggests that conscious choice plays a smaller role in our actions than most people assume. In particular, it often comes after brain activity that initiates bodily movements, and many researchers conclude that the conscious choice does not cause the movement. That conclusion raises the disturbing questions of whether and how we can ever really be responsible for anything. In the end, the issue of responsibility is both scientific and moral. Scientists discover fascinating information that can reveal how much and what kind of control we have over our actions, but then philosophers and legal scholars need to determine how much and what kind of control is enough to justify holding someone morally or legally responsible.

Sinnott-Armstrong is Chauncey Stillman Professor in practical ethics in the philosophy department and the Kenan Institute for Ethics.