The paper "Conspiracy Theories" by Harvard law professors Cass Sunstein and Adrian Vermeule is a warning for all 9/11 Truth groups. Although the paper is allegedly about conspiracy theory in a general sense, it is clearly centered on 9/11. I submit that this indicates a rising concern within certain powerful but ill-defined circles. Below is a self-explanatory segment from Sunstein's Wikipedia page...
Conspiracy theories and government infiltration
Sunstein co-authored a 2008 paper with Adrian Vermeule, titled Conspiracy Theories, in which they wrote, "The existence of both domestic and foreign conspiracy theories, we suggest, is no trivial matter, posing real risks to the government’s antiterrorism policies, whatever the latter may be."
They go on to propose that, "the best response consists in cognitive infiltration of extremist groups", where they suggest, among other tactics, "Government agents (and their allies) might enter chat rooms, online social networks, or even real-space groups and attempt to undermine percolating conspiracy theories by raising doubts about their factual premises, causal logic or implications for political action."
Sunstein and Vermeule also analyze the practice of secret government payments to outside commentators, who are then held out as independent experts; they suggest that "government can supply these independent experts with information and perhaps prod them into action from behind the scenes," further warning that "too close a connection will be self-defeating if it is exposed."
Sunstein and Vermeule argue that the practice of enlisting non-government officials, "might ensure that credible independent experts offer the rebuttal, rather than government officials themselves. There is a tradeoff between credibility and control, however. The price of credibility is that government cannot be seen to control the independent experts."
This position has been criticized by some commentators,   who argue that it would violate prohibitions on government propaganda aimed at domestic citizens.
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