Sunday, world leaders gathered in Paris to mourn the 16 victims gunned down in the Charlie Hebdo and kosher supermarket attacks. President Obama was notably absent, but he sent a message of support. So did officials here in China, where a state-owned newspaper called the attacks “another reminder of the threat of religious extremism to world peace and human dignity.”

But the key to human dignity — and the principle for which the cartoonists at Charlie Hebdo gave their lives — is freedom of expression. And it’s routinely flouted by Chinese authorities, who seized upon the Paris massacre to underscore the dangers of letting citizens speak their minds.

“A few Western media outlets had made sarcastic remarks about the Islamic prophet,” one newspaper editorialized, referring to Charlie Hebdo’s cartoons of Muhammad, “yet the Westerners think that this is ‘freedom of speech.’” Indeed, a second news portal declared, China’s limits on personal expression have helped prevent the kind of religiously inspired terrorism that stunned the world last week. “The lack of such freedom in China is in fact a blessing for all ethnic groups in the country,” the portal concluded.

Let’s leave aside the fact that China — despite its strict censorship policies — has faced violent attacks from separatists in the predominantly Muslim western province of Xinjiang. The most cynical claim here is that free speech is a “Western” value, when many Chinese people are obviously clamoring for it.

And cartoonists have often led the charge. Consider Kuang Biao, whose account on Weibo — the popular Chinese micro-blogging network — was abruptly shut down by state authorities two years ago. One of Biao’s now-censored cartoons indicted censorship itself: Under the caption “Mainstream media,” he drew a caged bird with a pen in its beak....