Abstract

In this chapter we will argue that the capacities necessary to moral and legal agency can be understood as executive functions in the brain. Executive functions underwrite both the cognitive and volitional capacities that give agents a fair opportunity to avoid wrongdoing: to recognize their acts as immoral and/or illegal, and to act or refrain from acting based upon this recognition. When a person’s mental illness is serious enough to cause severe disruption of executive functions, she is very likely to lack substantial capacities necessary to be law-abiding. Our analysis supports the Model Penal Code test for legal insanity over the traditional M’Naghten test, because the Model Penal Code test allows either severely diminished cognitive or volitional capacities to warrant an excuse to criminal culpability. We will provide a nuanced account of the ways in which mental illness can erode executive function, as well as an explanation as to why severe diminishment of executive functions caused by mental illness, but not some other causes, is exculpatory.