Philosophers typically rely on empirical data when they comment on psychopaths' moral responsibility. Many argue that psychopaths, as per the data, suffer from significant impairments in the precursors of moral reasoning and behavior, and therefore they should not be held morally responsible for their actions. However, careful analysis of these studies shows that this view is mistaken. We discuss how several philosophers--perhaps following the lead of social scientists--have systematically misinterpreted or simplified psychological data to support their conclusions about psychopaths' responsibility. We discuss four data sources: Case studies, the moral/conventional distinction task, fear conditioning, and facial affect recognition experiments. We examine how errors in the interpretation of these data have influenced, for the worse, the moral responsibility discourse. We recommend that philosophers exercise more caution in drawing conclusions from the psychological data on psychopaths. [ABSTRACT FROM AUTHOR]