Laws and taboos against upsetting the tender-minded are everywhere. Polite society, by which I mean not only successive governments, but the wider bureaucracy and mainstream opinion, holds that it is wrong to cause offence, even to those whose views are offensive; wicked to be disrespectful even of those who are not worthy of respect. You can see today's censorious tendency at work in the explosions of fury on the internet and in the mainstream media modern Britons enjoy when they seek distraction from the economic crisis. The complainants do not merely wish to deliver well-deserved condemnations of Jeremy Clarkson, Jonathan Ross and other celebrity oafs. They want them punished or fired, or in the case of the Twitter users who posted a homophobic columnist's home address online, they appear to want them dead as well.

The classical liberal John Stuart Mill believed that the law could only punish the direct incitement to a crime. In his example, when agitators claimed that corn dealers starved the poor, the state had no right to silence them. Only if the agitators said the same to an angry mob gathered outside a corn dealer's home could the police move in. Mill does not say that the law should punish the incitement of hatred against corn dealers. Even if their critics made their neighbours despise them as rapacious capitalists, even if the criticism was unfair and caused them financial harm, corn dealers could not go to court.

How many liberals believe in Mill's liberalism today? Most reject his tolerant injunctions because they want to defend the social revolution of the late 20th century. They are opposed to racism, homophobia and misogyny for good reason, and know that the struggles against them extend human freedom. Whereas Mill would only allow the police to arrest a demagogue causing direct harm by whipping up a mob outside a mosque or a gay bar, they want to regulate writing and speech which does not directly cause crime in the name of a greater good. To use the phrase of the philosopher Joel Feinberg, they have replaced Mill's "harm principle" with an "offence principle", which holds that societies are allowed to punish speech that people find exceptionally offensive.