In the words of Scott Alexander:
Chronology is a harsh master. You read three totally unrelated things at the same time and they start seeming like obviously connected blind-man-and-elephant style groping at different aspects of the same fiendishly-hard-to-express point.
In my case this was less “read three totally unrelated things” and more “read one thing, then have current events look suspiciously related”. I have been working my way through Thomas Schelling’s “Strategy of Conflict”, which made precise the concepts we now call “Schelling points” and “Schelling fences”, among others. He was focused on the psychological game theory of positive-sum bargaining, particularly in the context of nuclear war.
Which I’m against. Do not punch Nazis. No, not even if they’re wearing spider armbands and shouting Heil Hitler. Imminent self defense only. “Bad argument gets counterargument. Does not get bullet. Never. Never ever never for ever.”
Why is free speech protected? Other good tools, it can be pointed out, are also usable for bad purposes. Abusers “set boundaries” to maintain their control, but boundary-setting is healthy in other contexts. We do not have a “right to set boundaries” that protects the misuse by abusers.
The first reason is the marketplace of ideas, which Scott defended more eloquently than I’m likely to manage. A good reply to a bad argument, or a morally terrible ideology, is one that addresses the substance, not one that silences it. Say there are only clueless idiots being wrong, and enlightened philosophers being right (or at least less wrong). 1000 clueless idiots can silence 10 enlightened philosophers just as well as 1000 enlightened philosophers could silence 10 clueless idiots. Or you could argue the substance; even if there are 1000 idiots arguing, the philosophers are probably going to win this one.
And because that’s true, we should be very skeptical of attempts to shut down speech. If you need to silence it, that suggests you don’t think you can beat it on the merits, while every day it sits out in the marketplace of ideas and doesn’t catch on is another snub, showing that their ideas are not worthwhile.
The second reason is where we get back to Schelling. He spends a couple chapters and spills a bunch of ink about points for implicit cooperation in cooperative games with no communication. The classic example is meeting someone in New York City, but the purest one is this:
Pick a positive number. If you pick the same as your partner, you both win.
The correct answer is 1. Not because of anything inherent, but because human minds tend to settle on it; if you line up all the integers, it comes first. Similarly, if two parachuters land on a map and don’t know each other’s locations, they should meet at whichever feature is most unique. On this map, meet at the bridge:
If there is only one building, and two bridges, meet at the building. And if right before you jumped, one of you said “if I got lost, I’d climb the highest hill around and look for my buddy”, then you go to the highest hill around.
This is culturally and contextually determined. If you have to coordinate on a number from the list “three eight ten ninety-seven seventy-three”, you’ll probably pick ten, but if you counted in base 8, you’d probably pick eight instead. And these natural coordination points determine points of reasonable compromise. A car salesman haggling doesn’t say “I will accept no less than $5173.92 for this one”, because no one would believe it. “I will accept no less than $5200”, though, we will believe (as much as we’ll ever believe a car salesman).
The same is true of free speech. There are reasons to think that free speech is more important. (See reason one.) But even if those reasons don’t cut it, everyone knows about them, and since the Enlightenment it has been treated as especially important. It’s more vivid in the USA, where we elevated it to the second right specifically protected in the Bill of Rights, but even in Europe, where its status is lower, everyone understands that protecting freedom of speech is special, even where they allow exceptions. Even if it isn’t, in an objective ethical calculus, actually worth special protection, we treat it as a bright line which only tyrants cross, and bending that bright line makes you appear legitimately tyrannical, whether you do it with the law, with violence, or with social warfare and campaigns of ostracism.