a valid assumption

Michael Moore:

... if you see someone trying to incite violence, start with the assumption that that person is an undercover Homeland Security or cop or whatever, because this is the history of America where those in charge have tried to ignite people, incite them to commit acts of violence; and I tell them, don't be incited. Just assume right away that person is not part of the Occupied movement if that's what they're calling on people to do.