It is very annoying that the English language does not distinguish between free speech the ethical value and free speech the legal right. I feel like many conversations would be far clearer and more sensible if different words were used for these two things.
For one thing, while most people who value free speech as a matter of ethics support the legal right to free speech, the converse is not true. I can believe deep in my heart of hearts that some speech ought to be censored– that the people who speak it ought to be punished in various ways up to and including being punched in their stupid fucking faces– without thinking that it would be a good idea to give the US government the power to censor that speech.
The reason is that I cannot give the US government the narrowly tailored Power To Censor Only Speech Ozy Doesn’t Like. I can only give them the power to censor speech that is generally unpopular. The one thing everything currently censored by the US government has in common is that it is wildly unpopular, whether for good reasons (saying false and malicious things about people, shouting at an angry torch-wielding mob mob that God requires you to burn witches) or bad ones (drawn child porn).
Of course, much speech I do think should happen is very unpopular (such as pro-vegan activism) and much speech I think shouldn’t happen is very popular (such as saying cruel things about trans people).
So legal free speech is in the interest of all groups who want to say unpopular things. You get weird fucking allies in free speech defense: for example, a recent ACLU case’s defendants included PETA (message: “go vegan”), an abortion provider (message: “abortion pills available cheaply, quickly and privately”), the ACLU itself (message: the text of the First Amendment), and Milo Yiannopoulous (message: “everyone hates me! buy my book”). These groups have nothing in common with each other except that lots of people would like them to shut up and go away. But a legal precedent that protects any one of them would protect all four.
I am always puzzled that centrists are generally more fervent defenders of the legal right to freedom of speech than leftists are. It seems to me there ought to be a whole bunch of centrists going “wait, you mean we can silence the alt-right, the Nazis, the communists, Black Lives Matter, and PETA all at once?”
Some people argue that, in reality, it is possible to put up a fence on the slippery slope. The typical example is Germany, which bans Holocaust denial and displaying Nazi symbols. Of course, Germany has recently passed a law fining social networks who don’t delete “blatantly illegal” content within 24 hours, which may include censorship of statements like “we shouldn’t shield Muslims from criticism.” So I’m not sure that they’re doing a great job on that “only censor some of the unpopular opinions” thing.
However, this argument does not apply to any forms of censorship which are not being done by the government. When you advocate for or against legal free speech, you are only affecting the behavior of one entity, which has defined powers and acts based on precedent. But the conscientiousness of my behavior does not have any consistent effect on the behavior of my political opponents. While it may occasionally happen that people justify their anti-ethical-value-of-free-speech behavior with “but my opponents did it first!”, if their opponents were very conscientious about the ethical value of free speech those people would probably just decide that the ethical value of free speech was an Enemy Thing and people who support it are evil. So it goes.
That doesn’t mean that one should not support the ethical value of free speech. I myself support it. You just have to make arguments for it based on the value of people being able to speak freely, not porting over arguments from the legal right to free speech where they don’t belong. And even if you don’t value free speech ethically– which many people don’t!– if you have ideas that are outside the Overton window it is within your best interest to protect the legal right to free speech. For that reason, you should not use the government as an instrument of censorship, and should instead use boycotts, protests, discrimination, harassment, etc. as tools.