And free speech doesn't mean anything at all unless it includes the freedom to say things that some people will very strongly dislike. As John Stuart Mill put it,
Of course, words are sometimes used to do more than express an opinion, and where they an do great harm that is a horse of quite a different colour. Incitement to criminal behaviour is always wrong and does not come under the heading of free Speech within the law.
Hence it isn't an attack on free speech within the law to stop people from saying things which can reasonably be interpreted as encouraging others to attack or harm any group of people.
Such behaviour, alongside threats of violence and other clearly abusive comments can be and often is, prevented.
Unfortunately it is not always easy to draw the line between abusive statements and those which are merely criticism and we have seen again and again over the past few years that some people will use rules designed to prevent incitement to violence to try to censor views that they merely strongly disagree with.
People should have the right not to be murdered, physically attacked, discriminated against or threatened, and being threatened includes being subjected to language so hostile that a reasonable person could find it threatening. But nobody should have the right not to be offended.
I don't say this because I think being offensive is a good idea. I say it because, given how easy it is to offend some human beings, it is impossible to argue that everyone has the right not to be offended without effectively abandoning any meaningful commitment to freedom of speech.
I have very little time for the former Deputy Leader of UKIP, Suzanne Evans and, as I did not hear or see the BBC Newsnight broadcast that she has just been suspended from twitter for referring to, have no wish either to endorse or disagree with her comments.
However, if Guido Fawkes is right that Evans has been suspended from twitter because of a tweet in which she suggested that a trans woman had not been 'ladylike' on that programme this would appear on the face of it to be a classic example of the sort of overzealous reaction which fails to distinguish between criticism and abuse.
I have tweeted that
It will be interesting to see if I get into trouble for that.
It should be possible to disagree with the absolute sewer of abuse that gets thrown at many people in politics at the moment, particularly women and members of ethnic minorities, without supporting the censorship of mild or even fairly robust criticism.
Another quote on free speech, this one much more recent from the journalist Nick Cohen: