The target was freedom of expression, a value so fundamental it's recognized in the English Bill of Rights (1689), the French Declaration of the Rights of Man (1789), the U.S. Bill of Rights (1791) and the U.N. Universal Declaration of Rights (1948).
And the world reacted commensurately, with a unity that was fierce, angry and rare.
"Humor is the canary in the coal mine of free speech," said Bob Mankoff, cartoon editor of The New Yorker magazine, after gunmen stormed the offices of a French satirical newspaper called Charlie Hebdo that caricatured the prophet Mohammed. "We all have to stand up today, whether we are humorists or not.''
Condemnation of the attack extended from Russian President Vladimir Putin to WikiLeaks co-founder Julian Assange, who tweeted: "The world must now avenge Charlie Hebdo by swiftly republishing all their cartoons.''
One tweet, by a woman named Emily Koch, summed up the defiant mood: "You can kill journalists, cartoonists. You can't kill the freedom of the press. You have only made their message stronger.''
Tens of thousands took to the streets to protest the killings, and to social media, where "Je Suis (I am) Charlie" was the cri de coeur from Montmartre to Mumbai. In Paris, staffers of the French wire service Agence France-Presse stood before cameras, holding signs with the slogan.
Salman Rushdie, who spent years in hiding after his novel, The Satanic Verses, elicited a death warrant from Iranian religious leaders, called on the world to "defend the art of satire, which has always been a force for liberty and against tyranny, dishonesty and stupidity. ... Religions, like all other ideas, deserve criticism, satire and, yes, our fearless disrespect."
"The kind of blasphemy that Charlie Hebdo engaged in had deadly consequences, as everyone knew it could … and that kind of blasphemy is precisely the kind that needs to be defended, because it’s the kind that clearly serves a free society’s greater good. If a large enough group of someones is willing to kill you for saying something, then it’s something that almost certainly needs to be said, because otherwise the violent have veto power over liberal civilization, and when that scenario obtains it isn’t really a liberal civilization any more. Again, liberalism doesn’t depend on everyone offending everyone else all the time, and it’s okay to prefer a society where offense for its own sake is limited rather than pervasive. But when offenses are policed by murder, that’s when we need more of them, not less, because the murderers cannot be allowed for a single moment to think that their strategy can succeed."