A report into internet censorship in China indicates that it does not clamp down on free speech in the way that many westerners think.
Harvard University social scientist Gary King said that while the Chinese censorship machine is comprehensive it does not kill off all comment.
Talking to NPR, King said that the Chinese state does not censor everything. There are millions of Chinese people who talk about millions of topics. But the effort to prune the internet of certain kinds of information is unprecedented.
His studies refute popular ideas about what Chinese censors are after.
King said that China actually permits "vitriolic criticism" of leaders and governmental policies. But the state comes down hard on any move to get people physically mobilised to act on such criticism.
For example, King cited the case of a Chinese mother who once protested against a local official outside his hotel. Her demonstration led to online fury on social media sites. But since the action was almost entirely online the posts went uncensored.
Essentially, you can say what you like about the government, but if you try to get a demo together, you could be censored and have a knock on your door, King said.
Susan Shirk, an expert on China at the University of California, San Diego said that the findings make a lot of sense. In an authoritarian state, Shirk says, leaders are unsure about public sentiment because there are no elections or public opinion polls to gauge popular views.
Allowing criticism, she explains, is actually a smart intelligence-gathering move.
If people protest against local officials, top leaders monitoring the criticism could have them removed, leading to greater faith in the regime.
On the other hand after an earthquake damaged a nuclear power plant, people believed, wrongly, that eating salt could protect them against disorders linked to radiation. There was a run on salt and people physically held meetings about the crisis.
Media posts that catalogued these activities were censored, King said, because the online commentary corresponded to a physical, public result.
Oddly, censorship of physical mobility was automatic, even if it was good for the government.
If a citizen wrote a post suggesting having a big party for government officials who were doing a great job, that will also be censored because it means moving people to an event.
The logic is that people with the capacity to generate turnout for a pro-government rally might develop the experience to run an anti-government protest.
King said that if a government makes it impossible for people to learn about collective action events then people outside the government don't have the ability to move other people and the leaders can protect the regime.