Moral insanity and practical reason

The psychopathic personality disorder historically has been thought to include an insensitivity to morality. Some have thought that the psychopath's insensitivity indicates that he does not understand morality, but the relationship between the psychopath’s defects and moral understanding has been unclear. We attempt to clarify this relationship, first by arguing that moral understanding is incomplete without concern for morality, and second, by showing that the psychopath demonstrates defects in frontal lobe activity which indicate impaired attention and adaptation to environmental conditions which are relevant to the formation of complex intentions. We argue that these frontal lobe defects can help to explain both the psychopath’s apparent insensitivity to morality and his characteristic imprudence.