By NEIL MacFARQUHAR

CAMBRIDGE, Massachusetts - Troll through the Iranian blogosphere and you can find all manner of unexpectedly harsh critiques denouncing the government of the Islamic Republic, from reformists who revile it and conservatives who support it.
One conservative blogger deplored inflation undermining the middle class, saying it forced girls into prostitution to support their families. Others identified themselves as fans of President Mahmoud Ahmadinejad, yet they condemned government corruption and what they called arbitrary arrests. A fourth said that government statistics were nonsense.
What gets filtered out is not entirely predictable either. Some religious topics are deemed unacceptable. The government blocked the site of a blogger advocating the Shiite Muslim custom of temporary marriage, which is legal and considered a way for the young to relieve their sexual frustration without breaking religious laws.
Over all, a new study by the Berkman Center for Internet and Society at Harvard Law School shows that Iran’s blogosphere mirrors the erratic, fickle and often startling qualities of life in the Islamic republic itself. The rules of what is permissible fluctuate with maddening imprecision, so people test the limits.
In 2004, according to Human Rights Watch, 21 bloggers or people who worked at Internet news sites critical of the government were arrested, and some of them were tortured.
The study, conducted over the last year by the Berkman Center, was financed by the United States State Department . The research being released on April 13 documents what types of blogs are being posted in Iran. It will be available at cyber.law.harvard.edu/ publications/2008/Mapping_Irans_ Online_Public.
The researchers’ conclusion was that, “despite periodic persecution, many Iranians are able to use blogs to express “viewpoints challenging the ruling ideology of the Islamic Republic.
The study found that fewer than a quarter of blogs pushing for change, including those written by expatriates, were blocked. All kinds of conservatives maintain a lively debate about President Ahmadinejad.
“We don’t know if the government is not trying or not able to block as much as we thought, said John Kelly, the founder of Morningside Analytics, a New York company that took part in the study . Mr. Kelly said that the government “may allow a certain amount of online discourse to be there because it seems to underline the legitimacy of the system.
One conservative blogger mocked reformists for pretending to care about economic matters. “The nature of the reformists is actually extremism,’’ wrote a blogger under the name Shahrahedalat or the Highway of Justice .
Researchers admit that Iran’s filtering policy and techniques remain opaque. “Our sense is that the government in Iran doesn’t see the blogosphere as bad as a whole, Mr. Kelly said . “What they are trying to do is to promote more young religious voices, to pile as many conservatives into the network as they can.
Mehrangiz Kar, an Iranian dissident in Boston , said that bloggers are not permitted to criticize the Islamic system itself, but they are far freer than writers for newspapers or other news media. “These Web logs are very effective, she said. “They create conversation. Not just about elections or democracy, but about cinema, theater, arts, literature. These fields are very important for changing that society.