The fact is that society has always drawn lines about what speech and behavior is and isn't acceptable in different venues and circumstances. Facebook's choice to censor hate speech is no different from a bar, restaurant, or department store asking someone to leave for shouting the N-word at fellow shoppers. It's a private non-governmental entity making a choice about how they want their users to act on their platform.
Furthermore, free speech claims in favor of hate speech ignore the real material costs in human lives that facilitating hate speech incurs. While I greatly value free speech personally, I also greatly value human lives and the ability of all people to meaningfully participate in society without facing systemic oppression, violence, and hatred.
Tolerance must inevitably come face-to-face with intolerance, and if we don't act to stop the worst kinds of hatred and intolerance they fester and decay the ideals that allow tolerance to flourish at all.
Let's not be disingenuous: democracies also want to limit the speech of authoritarians. And they probably should, because every idea that's broadcast will garner some following. It's human nature. Your knife doesn't only cut one way.
Are they? Let's see the most important difference:
Is a public square privately owned? No. It is owned by the community, usually the council.
Is a restaurant privately owned? Yes. The proprietor has the option to evict people at will, as long as they do not discriminate against minorities in the process.
Do hate speech laws apply in a public place? Yes. If someone states racist things in public, they may be put in prison for hate speech.
Do hate speech laws apply in a private place? It depends on if this space is open to the public, and on the event being held. Generally, yes.
Is the owner allowed to evict any member at will from a public square? It depends. If the person is being harmful towards others, they may be removed from the square and detained, and sometimes even charged a crime.
Is the owner allowed to evict any member at will from a private square? Yes, as long as they do not discriminate against minorities when doing so.
As you can see, the attribute you have brought up does not matter. Facebook has the legal right to remove people for speech, as long as it does not discriminate against minorities in the process.
Many public squares are privately owned these days.
> Facebook has the legal right to remove people for speech
No-one is disputing that. Grandparent wrote "It’s a space where free speech should be defended," not "It's a space where free speech is protected by the law." The lack of legal protection for speech in this kind of space makes it all the more important that individuals stand up for it.
Free speech policies that would effectively harbor hate speech - also protect your speech from being labelled as such, and then censored, or worse. There are a disturbing number of places still left in this world, where controversial speech can get you jailed, or killed - with the blessing of, or by a government.
Humans can't be trusted, by and large, to be benevolent censors.
Speech promoting violence against some group of people, and not for defense purposes. No subjectivity there.
Of course, you may very well ask, isn't it trivial to construct an almost identical argument to justify violence against almost any particular category of people you'd care to name? Hopefully your interlocutor won't respond by punching you in the face.
> Furthermore, free speech claims in favor of hate speech ignore the real material costs in human lives that facilitating hate speech incurs.
What material cost? Censorship advocates continually assume that hate speech must have large and personal costs, but in my experience, present no evidence. The benefits of censorship are not apparent. The costs, however, are clear in the historical record: slowed scientific progress, emotional distress, and atrocities that might have been avoided through vigorous public discussion. And it's always been in the name of the public good, or saving souls, or protecting the innocent, or some other unassailable and noble good that people with power have forced others not to say certain words. The idea that no, this time, it's different suggests a certain historical hubris.
I'd wager that throughout history, there's never been a society that's made its people happier or better-off through censorship. I'd love to see a counterexample if you can find one.
For instance, the costs of censorship are, interestingly enough, also the costs of not censoring free speech. Slowed scientific progress (due to the rise of anti-intellectualism), emotional distress (pretty obvious how some types of free speech cause this), and atrocities (e.g. Charlotesville) could have been avoided through censorship. Those are the material costs of allowing unbridled, "hate group" free speech.
On a side note, I am very personally conflicted on this topic. It was strange to read your comment and strongly agree with some statements and then very strongly disagree other statements.