“What can government do about conspiracy theories? Among the things it can do, what should it do? We can readily imagine a series of possible responses.
(1) Government might ban conspiracy theorizing.
(2) Government might impose some kind of tax, financial or otherwise, on those who disseminate such theories.
(3) Government might itself engage in counter-speech, marshaling arguments to discredit conspiracy theories.
(4) Government might formally hire credible private parties to engage in counter-speech.
(5) Government might engage in informal communication
with such parties, encouraging them to help. Each instrument has a distinctive set of potential effects, or costs and benefits, and each will have a place under imaginable conditions.

However, our main policy idea is that government
should engage in cognitive infiltration of the groups that produce conspiracy theories, which involves a mix of (3), (4) and (5).
“ ... One line of thinking denies that conspiracy theories matter. There are several possible reasons to think so.
First, conspiracy theories may be held by only a tiny fraction of the population. Perhaps only a handful of kooks believe
that U.S. government officials had any kind of role in the events of 9/11.
“ ... 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.”
— “Conspiracy Theories,” Cass R. Sunstein, Adrian Vermeule,