Cohen is properly dismissive of the phonily self-pitying language of Islamists and the usage of "insult" as the cover for terror and murder. He is unmoved by the damage done by the victimless crime of blasphemy, and deplores the illegitimate extension of arguments against racism to suppress criticism of religions. He condemns the racism of anti-racists, the shamelessness of Islamism's "anti-imperialist" allies on the secular Left.

But he is also right that censorship is not limited to Islamists. Free thinkers, he proposes, have just made a better job of containing the censoring practices embraced by zealots of other religions — though the story of M.F. Husain, the Muslim artist who fell foul of what Cohen refers to as the self-pitying and vicious world of Hindu sectarianism, is evidence of the limits of that "containment".    

And then Cohen surprises us, by being right too about WikiLeaks. He writes: "For all my liberalism, I cannot think of one honourable reason why governments should not be able to keep information secret that might be used by the Taliban to compile a death list." What is more, for all his reservations about the development of privacy law, he also writes: "I accept that the judges will have to tackle the explosion of character assassination on the Net." He regrets the loss of British reticence and the coarsening of public life, though he finds the decline in deference has compensated for the decline in civility.

Cohen is right that the struggle for freedom of speech is a political struggle. He offers as an example the mobilisation in support of Simon Singh, "the most successful British free-speech movement since the campaign 50 years previously against the obscenity laws the state used to prosecute Penguin Books for publishing Lady Chatterley's Lover". The internet does not itself liberate, Cohen reminds us. On the contrary. Both the powerful and the weak can use internet technologies. Techno-utopianism is a dangerous distraction, encouraging the illusion that the censors can be defeated by the click of a mouse.  

Cohen celebrates Milton's Areopagitica (1644) and Mill's On Liberty (1859). His own book stands alongside them.