Ethics and the Brains of Psychopaths: The Significance of Psychopathy for our Ethical and Legal Theories

The emerging neuroscience of psychopathy will have several important implications for our attempts to construct an ethical society. In this article we begin by describing the list of criteria by which psychopaths are diagnosed. We then review four competing neuropsychological theories of psychopathic cognition. The first of these models, Newman’s attentional model, locates the problem in a special type of attentional narrowing that psychopaths have shown in experiments. The second and third, Blair’s amygdala model and Kiehl’s paralimbic model represent the psychopath’s problem as primarily emotional, including reduced tendency to experience fear in normally fearful situations, and a failure to attach the proper significance to the emotions of others. The fourth model locates the problem at a higher level: a failure of psychopaths to notice and correct for their attentional or emotional problems using “executive processes.” In normal humans, decisions are accomplished via these executive processes, which are responsible for planning actions, or inhibiting unwise actions, as well as allowing emotions to influence cognition in the proper way. We review the current state of knowledge of the executive capacities of psychopaths. We then evaluate psychopaths in light of the three major philosophical theories of ethics, utilitarianism, deontological theory, and virtue ethics. Finally, we turn to the difficulty psychopath offenders pose to criminal law, because of the way psychopathy interacts with the various justifications and functions of punishment. We conclude with a brief consideration of the effects of psychopaths on contemporary social structures