Free speech has many false friends and straw-enemies. Some of those misapprehensions come from the land of freedom and milk and honey and stars and stripes and things. Some come from inside of the Canadian academy. Some call themselves leftist, some right-wing. The conversation, at present, is all a bit warped. But if you wanted to get things straight, you could also consult the classics if you wanted, right from the horses’s mouth — Mill’s On Liberty.
On Liberty is sometimes mischaracterized as a kind of free speech absolutism, i.e., for whom one cannot limit speech on the basis of content, and/or which is directed only at the proprieties of government intervention and not social justice among individuals. If it were those things, it would be boring and wrong. In fact, though, Mill’s argument has all sorts of nuances and compelling features that, at the very least, make it worthy of continued attention. His endorsement of freedom of speech is not absolutist, since the principle of liberty is a function of his harm principle. Hence, he does endorse limitations to speech, and does believe it is sometimes justifiable to sanction the speech of others. You just have to be sensitive to the qualifications.
The first two limitations on speech worth mentioning right off the bat, and which many people reading this already know:
a) Only applies in modern contexts and between adults. Mill’s defense of free speech is a point about how we ought to design modern political institutions and culture which are responsive to reason. For roughly the same reason, a parent can limit the speech of a child, since children are ostensibly not capable of rational conversation. Or so says the parenting manuals in Victorian era England, presumably.
b) Contextual limits. The defense of freedom of speech does not prevent us from limiting the speech of someone who is inciting of mob violence (e.g., the corn-seller’s case). Plausibly enough, the American Court offered the example of yelling fire in a crowded theater as speech that can be sanctioned. (Implausibly, this was done to justify government sanctions on wartime dissidents.)
So, with those caveats out of the way, the question is: “Can we, people living in relatively evolved political societies, and speaking in non-incitement contexts, ever sanction someone for the contents of their speech?”
The answer depends on who you are — a government or a private citizen. For governments, the answer is pretty much a flat ‘no’. A government needs to lay off imposing sanctions on individuals for the things that individuals say. Hence, Mill thinks that blasphemy laws, and even libel laws, are legislatively wrong. An interesting additional question is whether or not legal restrictions on hate speech — e.g., Canadian restrictions on hate propaganda — are directed at harms based on content or context. (FWIW, my inclination is to regard propaganda as essentially contextual in nature, and expressed hatred as intending incitement, and therefore to see it as analogous to the corn-seller’s case. But this seems to be a matter of interpretation, and reasonable people may interpret it differently.)
Some of the people who call themselves libertarians seem to think that freedom of speech only concerns governmental regulations, not interactions between private citizens. But this is not so; private citizens are obliged to respect freedom of speech as well. It is just that their internal calculations have to be a bit more nuanced.
Consider the fact that there are many kinds and qualities of bad effects that we can visit on others when we target them with speech:
Hurt vs. harm. Suppose there’s a difference between subjective hurt and objective harm. We can distinguish them as follows: an action produces subjective hurt when the act produces a negative effect on the patient, but only on the condition that the patient permits themselves to be hurt; while an action is an objective harm if the negative effect is visited on the patient irrespective of whether or not they recognize it. So, you can’t necessarily be held to account just because a person chooses to interpret a turn of phrase in a way that makes it appropriate to feel slighted. The idea is that you are not necessarily blameworthy if you happen to hurt someone’s feelings, so long as they are not otherwise worse for the wear. In contrast, there is a prohibition on intending to cause objective harm to others. So, e.g., even if libel laws make for bad governmental policy (according to Mill), private citizens are doing wrong if they lie about others and cause reputational damage.
Acts vs. facts. Mill notices that there’s a difference between objective harms related to (a) the statement of facts about the target, and (b) objective harms delivered through the act of speech. For an example of the first kind of harm: by calling a thief “thief”, you might end up causing the thief harm, in a sense; but the harm issues from the facts, not from the act of talking about it. And it is fine to do someone objective harm just by reporting accurately on the vile things they’ve said or done. If a pizza guru says, “I hate gay people”, then I can tell ordinary decent folks what the pizza guru said, and they can boycott him. And if a whistleblower says, “My organization is killing people with drones”, and they can prove it, then that speech is permissible, too, and so they ought not be sanctioned by the government.
On the other hand, you cannot just go around sanctioning people for saying things you don’t like, causing them objective harm through the creative powers of speech. That is, you shouldn’t engage in “vituperative” speech: by which he seems to mean gratuitous vilification, heckling and shaming, character assassination, and so on. He argues that the mischief that arises from these sorts of conversational bludgeons “is greatest when they are employed against the comparatively defenceless; and whatever unfair advantage can be derived by any opinion from this mode of asserting it, accrues almost exclusively to received opinions. The worst offence of this kind which can be committed by a polemic is to stigmatise those who hold the contrary opinion as bad and immoral men.” Instead, you should engage in the “real morality of public discussion“, which is to say, you should engage in good faith: “giving merited honour to every one, whatever opinion he may hold, who has calmness to see and honesty to state what his opponents and their opinions really are, exaggerating nothing to their discredit, keeping nothing back which tells, or can be supposed to tell, in their favour.” In other words, you should not contribute to the ongoing eternal garbage-fire of life on Twitter.
But, once those speech acts are taken off the table, is there any kind of speech left? Is all of our discourse turned into anodyne or inert? No — you are only barred from intending objective harm on the basis of the speech acts independently of the facts, i.e., through vituperative speech. Everything apart from that is fair game. You can speak falsely, and can hurt feelings. What you can’t do is engage in bad faith.
At any rate, this was my reading of Mill. Maybe you have your own interpretation. Either way, I think it is well worth revisiting his essays every so often, because it rewards close reading.