Nick Cohen of the Spectator gets it:
As for the anarchists, let us be honest and acknowledge political violence is not always futile. If there isn’t violence, the media will give only perfunctory coverage to a demonstration, something that ought to worry my colleagues more than it does. Today’s proponents of breaking the law and scaring shop girls can also say that riots and a mass refusal to pay destroyed the poll tax in Mrs. Thatcher's day. I am sure readers can throw the moral argument against political violence in a democracy in their faces, but for me the decisive point is that by the time of the protests against the poll tax exploded, virtually everyone in Britain except Mrs. Thatcher had accepted the case against it.
I have long noted that many political strategists suffer from the desire to prefer politically correct shibboleths over cold, unpleasant truths. For instance, many believe that political violence doesn’t work. While it true that middle class voters are repelled by the sight of professional left-wing vandals ritualistically fighting in the street, history nevertheless teaches us that political violence is also an effective way of getting what you want. Many people can be scared into ‘going along to get along’ with an idea that they may be repulsed by. Cowards and thugs – not a pretty picture of society, but one paid political realists should acknowledge more than they actually do.
None of the foregoing analysis is made to justify political violence. When the left equates rioting with political speech, they have it exactly backwards: rioting is the negation of political speech; it is the negation of democracy; it is the negation of a civil society. My purpose in this article is only to point out the frightening fact that political violence does work, and more often than we acknowledge. Which is all the more reason to ruthlessly crush it when it happens.