‘We are all potential assassins’, writes P.G. Zimbardo; but, he might have added, few of us are assassins in reality. We may ask why human beings commit appalling acts of violence; the need to answer this question is behind much writing on ‘aggression’. But it is equally appropriate to ask why most of us, even in the face of provocation, are peaceable most of the time. The previous chapter disposes of attempts to find answers in ethology, but there are other obstacles to understanding. One is the vast range of phenomena put under the heading of aggression.

Meanings

It is sometimes said that aggression is difficult to define. Such a statement might be accepted if it referred to writings about activities of a single kind with indistinct boundaries. As the lists opposite show, this does not apply to aggression: the term has been used so variously, that sometimes it could be replaced by ‘behavior’ with no loss of meaning.