This is a quote from Andrew Cooper at the Tavistock Clinic:
"The task facing us is to work out how we can improve the capacity of our practitioners to tolerate "thinking the unthinkable" and so have a better chance of interrupting the unthinkable things to which some children are subjected. Naming the actions of abusers as evil, or demanding practitioners' resignations, serves only to stop us thinking. Hard to bear emotionally, very hard to understand, frighteningly difficult to confront - these are the tests with which these terrible cases face us."
He was talking about the vilification of the Baby P social workers. But in fact his point about the word 'evil' could equally be applied to anyone whom society wants (I would say needs) to call a Monster.
In calling people Evil, we hope we won't have to think about them any further, because Evil is not really susceptible to analysis or quantification. But we DO have to think about these people, just as we have to think about paedophiles if we're to understand them, (which we must do if we're to control them) and if we're to prevent children both from being harmed AND from becoming abusers themselves.
Evil also implies that they can be excised from society. But they have come from society, they are part of it. And parts of them are, to whatever degree, a product of society. We have to face that fact.