Dalrymple makes several interesting points about censorship in this article at Taki’s Magazine — on self-censorship, for one:

Normal people care about many things, but only to a moderate degree; for monomaniacs, their one thing is the meaning of their existence. So while they can devote their miserable lives to the persecution of those who think differently from them on that one, only moderately important subject, the persecuted do not care enough about that subject to risk much discomfort in order to expound what they see as the truth about it.

Thus censorship comes to exist in a supposedly free society, without any need of government oppression; it necessitates self-censorship, but it is censorship of the worst kind, for it leads to a situation in which only one view of the subject can be aired in public.