Evil has been defined as taking pleasure in the intentional inflicting of harm on innocent others, and ever since World War II social psychologists have been fascinated by the topic. Many of the formative thinkers in the field — Kurt Lewin, Stanley Milgram , Solomon Asch — were inspired by their experiences with, and observations of, what appeared to most people at the time to be the indisputable incarnation of pure evil. But what many saw as a clear demonstration of unredeemable and deep-seated malice, these researchers interpreted as more, in the words of Hannah Arendt, banal. From Milgram’s famous studies of obedience to Zimbardo’s prison study, psychologists have argued for the roots of evil actions in quite ordinary psychological causes. This grounding of evil in ordinary, as opposed to extraordinary, phenomena have led some to describe the notion of “pure evil” as a myth. A misguided understanding of human nature deriving both from specific socio-cultural traditions as well as a general tendency to understand others’ behavior as a product solely of their essence, their soul, as opposed to a more complicated combination of environmental and individual forces.

The issue of whether “pure evil” exists, however, is separate from what happens to our judgments and our behavior when we believe in its existence. It is this question to which several researchers have recently begun to turn. How can we measure people’s belief in pure evil (BPE) and what consequences does such a belief have on our responses to wrong-doers?