But he lived well before the age of the internet and maybe, you know, just maybe when the world changes we should adapt to it rather than to dogmatically hold that what one person thought a couple of hundred years ago should be enshrined and never ever be changed lest the sky falls down.
I completely agree that citing authority is not an argument. I only contend here that the GP made an inaccurate summary in dismissing Mill's argument; and that argument is only one chapter, not the whole book as you might think from the way it's cited. You might find it pretty on point: he wrote in Victorian times which were also a local maximum of social pressure to profess the correct thoughts. Also a time with unprecedented new media (though I don't recall that topic coming up in this chapter).
One of the problems with suppressing criticism of even things that are completely true and right, as Mill points out, is that people come to believe the true thing in only a hollow way. I've been thinking that may have happened to the doctrine of free speech itself in the U.S. -- becoming just a slogan kids learn to parrot in school. Hollow it enough and it's easily lost.
(Added: I found I could unflag your comment. I think the snark was undeserved but it wasn't nearly enough for flagging.)
I think you're well past that stage already. Plenty of people parrot the founders as though they had some kind of divine insight into what makes a good state, rather than to see political systems as subsequent attempts to learn from mistakes made in the past. It is very well possible that 'free speech' should be sacrosanct, but the US is doing a piss-poor job of showing that that is the case.
Political systems come and they go, so far the 'free speech' countries are not doing remarkably better than the countries with some limitations on free speech and it would be good to recognize this and to see what can be learned from each other rather than to put dogma first.
Variation in laws and norms is a valuable teacher, and there's a lot of shallow faith in the civic religion, agreed on that much. I'm kind of too lazy to argue with you here about the rest.
The affordances of social media could be much better designed for preserving the memetic edge the more true ought to have over the more false; OTOH the way Twitter and Facebook are going about this attempt at reform is heavy-handed folly that's already backfiring. (http://www.islandone.org/Foresight/WebEnhance/HPEK1.html from the 1980s shows by example that it is possible to think ahead about societal consequences of the design of communications media. That particular paper focused on more scholarly publishing, but it's not like that's unimportant either.)
I think the problem is advertising. Advertising causes media to focus on the controversy because it is what drives engagement. Business-as-usual would not drive engagement nearly as much as outrage does.
