That people are responsible for their own actions. You have no right to kill people or threaten them with violence because you take offense at what they say. You may enter a vigorous debate with them however threats of violence are off the cards from either party.
But I'm asking about freedom of speech.
Yes, people must be held to be responsible for their own actions unless by mental incapacity of any kind they are deemed not to be so. I think that's a given for any form of civilised society.
The reaction is not really germane, except inasmuch as provoking a reaction on purpose is or isn't an acceptable use of free speech.
What sorts of things are people free to say, in principle? What, if any, are the limits to free speech?
If someone directly threatens you then you may take defensive action.
Principle? You have a right to personal security and may infringe another person's right to the same if the cause you harm?
Muslims need to learn to take these cartoons on the chin. They are free to respond with caricatures that offend the other side.
That's not really a principle about freedom of speech. In fact it isn't a principle at all, because whatever you decide free speech is will apply equally to both sides of the debate.
If people cannot take responsibility for themselves, by not threatening others, then they need to have that responsibility forced on them for, as you say, the public good.
Clearly so, but not really the principles behind free speech.
Would you agree that the individual has the right to act in any manner which does not infringe the rights of another citizen?