Today we are all Charlie Hebdo. But what about tomorrow? And the day after that?

That’s when our commitment to free expression will really be tested, and in ways that are less obvious and prone to easy, social-media heroics. That’s when the battle lines over “allowable speech” will really become clear and we’ll see who’s standing where. If the recent past in America is any indication, we should be worried, as free speech and the marketplace of ideas it energizes are never really popular for very long. They are always suspended over a precipice, dangling by a slender thread that shows every sign of snapping.

Don’t get me wrong. It’s absolutely fantastic that Twitter and Instagram are overflowing with people from all over the world publicly stating solidarity not simply with the French satirical magazine whose staff was murdered by Islamist madmen, but the larger principle that speech and peaceful expression shouldn’t be subject to murderous reprisals. I think it’s especially great that Europeans are doing so, since that part of the world is no haven for free speech.

As the radical British Muslim cleric Anjem Choudary wrote on Twitter while the bodies were practically still bleeding out, “If freedom of expression can be sacrificed for criminalising incitement & hatred, Why not for insulting the Prophet of Allah?” Virtually every European nation has “hate speech” laws of some sort, most of which protect against the always-poorly defined slandering or libeling of this or that religious faith, along with a million other things. For god’s—Allah’s?—sake, Austria even threw joke historian David Irving in prison for denying the Holocaust, an action that accomplished nothing other than giving him greater standing among neo-Nazi idiots and salving the historical guilt of the first nation to sign up—willingly!—for Hitler’s genocidal madness.

Writing in USA Today, Choudary expanded on his anti-free-speech argument, using European law and custom to justify or explain violence. Given “curtailments” on freedom of expression, “why in this case did the French government allow the magazine Charlie Hebdo to continue to provoke Muslims, thereby placing the sanctity of its citizens at risk? It is time that the sanctity of a Prophet revered by up to one-quarter of the world’s population was protected.”

Even as he ignored an unsuccessful 2007 attempt by aggrieved Muslims to sue Charlie Hebdo under a stupid French law, Choudary invoked the same sort of “higher law” reasoning that underwrote protests by all sorts of radicals, such as St. Thomas More, Roger Williams, Henry David Thoreau, Gandhi, and Martin Luther King, Jr. in their finest moments. “Muslims consider the honor of the Prophet Muhammad to be dearer to them than that of their parents or even themselves. To defend it is considered to be an obligation upon them,” says Choudary. “This is because the Messenger Muhammad said, ‘Whoever insults a Prophet kill him.’”

That’s a gutsy, clever, contentious argument to make in the wake of an unambiguously despicable act. It’s gutsy, too, to pretend to speak for all of Islam, which like Christianity contains multitudinous interpretations of core doctrines. Choudary’s obvious logical sleight of hand—he conflates “incitement” and “hatred,” thereby equating action and thought so as to prohibit both—suggests that he is arguing in bad faith. But his case founders in a specifically American context, where “hate speech” is rightly protected under the First Amendment, which not coincidentally also guarantees freedom of religion and freedom of association.

Speech, religion, and association are inextricably intertwined, after all, and to try to separate them is the same thing as destroying them; it would be like trying to remove the color from a jug of paint. All spiritual obligations to Allah, Mohammed, Jesus, and Joseph Smith aside, constitutional guarantees of speech, religion, and association are precisely one of the reasons why American Muslims—and Catholics, Protestants, Jews, and others—are less likely to shoot each other here than to argue in the marketplace of ideas or, as important, ignore each other completely.

Yet we Americans shouldn’t be glib or smug in our devotion and commitment to free speech. Yes, we do typically do better than Europe (and Canada, too, which is frequently awful on this score). But even if free speech is guaranteed by law, it’s hemmed in by countless other trends, customs, and especially mind-sets that seek to reduce, restrict, and in some cases even criminalize speech.

The simple, awful truth is that free speech has never been particularly popular in America. When they’re not busy banning books such as the Harry Potter and Captain Underpants series (really), schools should drill into students that it’s pathetic that Lady Chatterley’s Lover and countless other books, films, and other forms of creative expression were banned for decades.

Back in the 1980s and early ’90s, it tended to be the right, especially the religious right, that sought to shut down art and expression that it found distasteful, obscene, and irreverent. That Jesse Helms harped on the minimal taxpayer funding underwriting Andres Serrano’s Piss Christ barely disguised conservatives’ larger game in shutting down art they found sacrilegious or distasteful. But it wasn’t just the right, or conservatives, who were forever being literally and figuratively pissed off. In 1989, when a student at Chicago’s Art Institute created an exhibit that invited the audience to step on an American flag, the Senate voted 97-0 to criminalize putting flags on the floor or ground.

As the World Wide Web was scaling up into a true mass medium, the Clinton administration, with the backing of a Republican Congress, passed the Communications Decency Act, which would have effectively subjected the Web to the same sort of dreary content regulation that attends to broadcast radio and television. The CDA was passed not in the name of censorship but in the name of protecting children from stumbling across sexual material. Only a surprising—and overwhelmingly free-speech—decision in 1997’s Reno v. ACLU saved us from such a debilitating law.

Today’s threats to free speech are more likely to come from “social justice warriors” on the left who say they are defending the feelings of those deemed to be crushed under the weight of supposedly systemic racism and sexism. The movement is most evident on college campuses. Twenty years ago, the ACLU inveighed against the rise of campus speech “codes or policies prohibiting speech that offends any group based on race, gender, ethnicity, religion, or sexual orientation.” Whatever the intention, the ACLU argued (and still does), such rules end up policing and punishing thought, which should be anathema anywhere but especially at a university. As the student rights group (FIRE) documents on an appallingly regular basis, the ease with which colleges infringe on expression and association is unceasing.

More recently, under the guise of protecting victims of sexual assault, the federal government tied higher education funding to creating on-campus legal proceedings that stripped defendants of due process rights. The silencing of defendants’ rights under federal guidelines is so egregious that even the overwhelmingly progressive faculty of Harvard Law School called the government’s actions beyond the pale. Then there’s the move toward “trigger warnings,” mandatory announcements that reading and discussing material such as The Great Gatsby may cause post-traumatic stress disorders, and the creation of a whole new range of offensive and thus actionable speech called “micro-aggressions.”

The atmosphere on campuses has gotten repressive enough that comedian Chris Rock no longer plays colleges. Citing examples such as University of California at Berkeley students trying to bar an appearance by Bill Maher because of his anti-Muslim jokes, Rock told New York that he “stopped playing colleges, and the reason is because they’re way too conservative… Not in their political views—not like they’re voting Republican—but in their social views and their willingness not to offend anybody… You can’t even be offensive on your way to being inoffensive.”

As my Reason colleague Elizabeth Nolan Brown has written, progressives may well come to rue the day they signed on to laws forbidding controversial speech based on the speaker’s perceived motivations. A Brooklyn graffiti artist was charged with a hate crime because her message criticized the NYPD and a professor lost a tenured position at the University of Illinois because his anti-Israel comments were labeled “hate speech.”

In America, these are the sorts of incursions against free speech and a truly unregulated marketplace of ideas that will persist and likely grow long after the dead in Paris are forgotten (just as Dutch filmmaker Theo van Gogh’s ghastly murder has been). We will likely never face the explicit limits on speech, religion, and association imposed by European countries, but we are kidding ourselves if we think similarly effective repression cannot happen here.

In fact, hate-speech laws may even become a reality. An October 2014 Economist/YouGov poll found roughly equal amounts of Americans supporting and opposing “a law that would make it a crime for people to make comments that advocate genocide or hatred against an identifiable group based on such things as their race, gender, religion, ethnic origin, or sexual orientation.” Thirty-six percent were in favor and 38 percent were opposed. Among Democrats, 51 percent supported such laws.

Those are troubling numbers, for unfettered speech is not incidental to a flourishing society. It’s the foundation upon which everything—from science to religion to community to politics—is built. We need to recover and grow the idea that the proper answer to bad speech is more and better speech. Or, as good, to ignore that which bothers and insults you. Tend to your own garden, to quote the great sage of free speech, Voltaire, and invite people to follow your example.

Yes, today we are all Charlie Hebdo, and that’s a great thing. But it’s tomorrow—and the day after tomorrow—that really matters.