THE CHINESE market — 1.38 billion people — has proven irresistible to many a Western corporate executive. It is entirely logical that Mark Zuckerberg, founder and chief executive of Facebook, might see China’s 721 million Internet users as an appealing audience, on top of the 1.8 billion people in the rest of the world who already use the platform. But Mr. Zuckerberg’s business logic should not blind him to the dangers of censorship in China.

According to the New York Times, Facebook has developed software that would allow a third party to suppress or censor posts from appearing in users’ news feeds. The software was developed to help Facebook get back into China, where it was blocked in 2009, and enjoys support from Mr. Zuckerberg. The option of third-party control might allow Chinese authorities or a partner in China to do the dirty work. Mr. Zuckerberg reportedly told Facebook employees in July at an internal forum that plans for reentering China were still nascent, but he added, “It’s better for Facebook to be a part of enabling conversation, even if it’s not yet the full conversation.”

Mr. Zuckerberg has made several trips to China and clearly wants in. But his logic here is faulty. The notion that exposure to open societies in the West would change China was popular some years ago, but for the most part the state remains a paternalistic overlord, imposing a massive cordon around Internet users inside the country. The Great Firewall keeps out Facebook and others seen as undesirable. President Xi Jinping has ramped up a campaign to squeeze Western influences out of China and force the news media to become ever more a mouthpiece of the ruling Communist Party. Mr. Zuckerberg should be especially wary of China’s multipronged strategy to censor and tame social media, which includes monitoring users and flooding social media with posts of government propaganda. Chinese companies have also been adept at welcoming technology from abroad just long enough to master it and then purge the visitors, as Uber discovered.

One has to ask whether, if Mr. Zuckerberg were able to secure a toehold, Facebook would on balance be bringing more openness to China or enabling behavior that has turned the country into a thought prison. Would Facebook be living up to its core mission “to make the world more open and connected” or would it be adding a brick to the Great Wall of authoritarianism? How long would it be before the Chinese authorities also demanded that Facebook localize its servers, putting all information on the mainland under the watchful eye of the dissent-crushing state apparatus?

For now, Facebook’s suppression software has not been rolled out and there are many hurdles to reentering China. Before taking any more steps in this direction, Mr. Zuckerberg should ask himself a central question: If Facebook accedes to the Communist Party’s demands, who will change more — China or Facebook?