Most journalistic defenses of free speech take the form of "shut up and speak freely." The Beast itself provides Exhibit A: Cultural news editor Michael Moynihan announced that "we're one of the few countries in the Western world that takes freedom of speech seriously," and indignantly defended it against "those who pretend to be worried about trampling innocents in a crowded theater but are more interested in trampling your right to say whatever you damn well please." To Moynihan, Rosenbaum could not possibly be sincere or principled; he is just a would-be tyrant. The arguments about harm were "thin gruel"—not even worth answering. Moynihan's response isn't really an argument; it's a defense of privilege, like a Big Tobacco paean to the right to smoke in public.
In contrast to this standard-issue tantrum is a genuinely thoughtful and appropriate response from Jonathan Rauch at The Volokh Conspiracy, now a part of the Washington Post's web empire. Rauch responds that
painful though hate speech may be for individual members of minorities or other targeted groups, its toleration is to their great collective benefit, because in a climate of free intellectual exchange hateful and bigoted ideas are refuted and discredited, not merely suppressed .... That is how we gay folks achieved the stunning gains we've made in America: by arguing toward truth.
I think he's right. But the argument isn't complete without conceding something most speech advocates don't like to admit:
Free speech does do harm.
It does a lot of harm.
And while it may produce social good much of the time, there's no guarantee—no "invisible hand" of the intellectual market—that ensures that on balance it does more good than harm. As Rauch says, it has produced a good result in the case of the gay-rights movement. But sometimes it doesn't.
Europeans remember a time when free speech didn't produce a happy ending. They don't live in a North Korea-style dystopia. They do "take free speech seriously," and in fact many of them think their system of free speech is freer than ours. Their view of human rights was forged immediately after World War II, and one lesson they took from it was that democratic institutions can be destroyed from within by forces like the Nazis who use mass communication to dehumanize whole races and religions, preparing the population to accept exclusion and even extermination. For that reason, some major human-rights instruments state that "incitement" to racial hatred, and "propaganda for war," not only may but must be forbidden. The same treaties strongly protect freedom of expression and opinion, but they set a boundary at what we call "hate speech."
It's a mistake to think that the U.S. system goes back to the foundation of the republic. At the end of World War II, in fact, our law was about the same as Europe's is today. The Supreme Court in Beauharnais v. Illinois (1952) upheld a state "group libel" law that made it a crime to publish anything that "exposes the citizens of any race, color, creed or religion to contempt, derision, or obloquy." European countries outlawed fascist and neo-Nazi parties; in the 1951 case Dennis v. United States, the Supreme Court upheld a federal statute that in essence outlawed the Communist Party as a "conspiracy" to advocate overthrowing the U.S. government. Justice Robert H. Jackson, who had been the chief U.S. prosecutor of Nazi war criminals, concurred in Dennis, warning that totalitarianism had produced "the intervention between the state and the citizen of permanently organized, well financed, semi-secret and highly disciplined political organizations." A totalitarian party "denies to its own members at the same time the freedom to dissent, to debate, to deviate from the party line, and enforces its authoritarian rule by crude purges, if nothing more violent." Beauharnais, Dennis, and similar cases were criticized at the time, and today they seem grievously wrong. But many thoughtful people supported those results at the time.