Free speech requires the Socratic "recognition that you almost certainly don't know everything," says Greg Lukianoff. Lukianoff, the founder of the Foundation for Individual Rights in Education (FIRE), diagnoses a humility deficiency in the new documentary Can We Take A Joke?

Last November, its indie film-fest premiere coincided with anti-speech protests at Yale and Mizzou. Now, you can catch it online and in hip urban movie theaters. It's worth a click, or a trip downtown, for civil libertarians—or indeed, anyone who likes to laugh.

The documentary, directed by Ted Belaker, is a civic-minded, slightly watered-down version of The Aristocrats. It boasts a cast of comedians—Lisa "Queen of Mean" Lampenelli, Gilbert Gottfried, Jim Norton, Karith Foster, Penn Jillette, Heather McDonald. Stacked against those comedy pros, Lukianoff isn't very funny. The stakes are high—no laughing matter, really—and the authoritarian shades of puritanical progressivism are a serious threat to liberty: A free society's survival depends on the open exchange of ideas, good and bad, funny and unfunny.

These comedians, proud professional descendants of public enemy Lenny Bruce, relish the political philosophizing, but they also depend on free speech to make a living. According to New York Times reviewer Neil Genzlinger, who seems to think he might actually know everything, Can We Take A Joke? is "one-sided" and "would be better if it also at least acknowledged the possibility that some jokes ought not be told." Really, variations on the famous Richard Pryor rule, "You can say anything that comes to mind, just so long as it's funny," come up so frequently in the film's 75 minutes that one has to wonder whether Genzlinger was paying enough attention. Going by the Pryorism, at least by its use in this context, some edgy jokes indeed are too offensive, jokes not actually funny enough to take the edge off. And, then, a cold audience will judge.

Diverse voices—from humorists to civil liberties lawyers—agree that protecting free speech promotes individual resilience, a resilience gained from exposure to a plurality of challenging, often distasteful ideas.

Comedians also riff on everyday horrors not just to push the limits of what's acceptable, but to lighten the load. Former college comedian Chris Lee, whose South Park-ian musical was swarmed by paid protesters in 2005, talks about his trials on screen. Since graduating, Lee has worked charity events, telling his tasteless jokes to audiences of AIDS and cancer survivors. Lisa Lampenelli considers her audiences' responses proof enough that touchy subjects need to be joked about. "Every time I do an AIDS-and-rape joke, it kills," she says. "And you know what? It's cause we're scared of it, and if you're running away from it and you're scared of it, you're a pussy. I think that's why we have to make fun of those subjects."

Theirs is not a new idea.

In a classic scene in the 1960s sci-fi novel Stranger in a Strange Land, a human man raised on Mars—the only son of a lost colony, now a "stranger" come to Earth—finally realizes the essential condition of our weird race: Being human means laughing at our own pain.

And, in the children's novel The Phantom Tollbooth (if you'd prefer a higher-brow reference here, you may be missing the point), the hero Milo and his friends learn the power of laughter while they're beset by demons, facing a failed mission and certain death. They're rushing to rescue Princesses Rhyme and Reason who'll restore joy and sensible order to the crumbling kingdom, when a demon called the Senses Taker sidetracks them first with mindless census-like forms to fill out, then by conjuring up what each most wants to see, smell or hear. While they're entranced, the hoard of demons advances. Milo, rapt by the illusion, drops the magical gifts he's gathered along his journey, and a package of laughs spills out—laughter so infectious they all join in. And just like that, the Senses Taker's conjurings fade: "'I'll steal your sense of purpose, take your sense of duty, destroy your sense of proportion—and, but for one thing, you'd be helpless yet.' 'What's that?' asked Milo, fearfully. 'As long as you have the sound of laughter,' he groaned unhappily, 'I cannot take your sense of humor—and with it, you've got nothing to fear from me.'"

In Can We Take a Joke? there's no radical revelation about the human condition. It's neither off-puttingly smart-ass nor particularly partisan. The only overt left-vs.-right commentary comes from ten-year-old clips of the late George Carlin, reluctantly pinning blame on the left—"We've all got to understand that we can expect censorship from the right wing, but to expect it from the left wing, from the politically correct wing, from the college campuses—that caught me by surprise."

And the most profoundly patriotic legal perspectives come from gay rights activist and legal scholar Jonathan Rauch, who says that the First Amendment doesn't work when Americans don't also value free speech in their hearts. He warns, "The only want way you find truth in public society is through public debate. Once you get into the business of saying you're going to prohibit things people find offensive or wrong-headed, that's where the most sensitive person in society gets to determine what all the rest of us can hear."

Ultimately, it's an optimistic film. Our need to laugh together will triumph over our fear of our own feelings. It's a repressed need, maybe mostly forgotten, comics muse in the film's final uplifting montage of commentary, but that fundamental requirement to laugh where it hurts—it's not going away.

So, can we take a joke? Yes, for the most part. And we who can should laugh loudly and often, at ourselves and others. It might just be the only way to restore rhyme and reason to the kingdom.