“Today we have techniques of manipulation on a scale that would have done Callicles proud. They are not playful transgressions; we do well to fear the link between such power and what passes for knowledge. If there is only persuasion, Plato warns us, there is no discourse except the confrontation of power and propaganda. If we cannot draw the line, he says, all means of persuasion will be acceptable. Violence may be done to us, in crude or subtle ways and we will not be able to stop it. Even worse, we may not be aware of it.”