Contemporary political theory has never been comfortable with the idea of evil. Indeed, the gradual, sporadic, but nevertheless incomplete secularisation of political discourse since the Renaissance has made the conceptualisation of absolute value deeply problematic. One response, dominant in the liberal tradition, is simply to deny that politics is the realm of absolute value at all. The pragmatic adjustment of competing interests in a scheme of social co-operation invites, at the very least, a moderation of tone. And increasing empirical awareness of the diversity of different schemes of (merely political) co-operation has made us (rightly) guarded in the language we use to defend specific positions. Modern liberals are unlikely to go to the stake for politics in any of its guises. Politics is not that important. We shouldn't get too excited about the give and take, and sometimes unseemly compromise, that characterises the banal politics of everyday life.

And yet atrocity remains to shock us – sometimes, indeed, to render us truly speechless. We mutter to ourselves, in all innocence, ‘how could anyone do that?’ Modern (predominantly secular) political theory ceases to be very helpful when confronted with extreme experiences. It is not surprising that an earlier religious language is sometimes seen to have far richer resources in such cases, even for thinkers whose cast of mind is otherwise thoroughly secular. It doesn't usually help much to characterise political opponents as ‘evil’ in an unqualified sense.