The best means to stop a Hitler would be to show the actual, ugly truth of where he'll lead us. Very few lies about Hitler could match the real horror.
In a world with rational voters, yes. In our world you might want to start a false rumor such as Hitler's Jew hating is just a false cover for his true desire to reduce social welfare payments
Scott, known on LessWrong as Yvain, recently wrote a post complaining about an inaccurate rape statistic.
Arthur Chu, who is notable for winning money on Jeopardy recently, argued against Scott's stance that we should be honest in arguments in a comment thread on Jeff Kaufman's Facebook profile, which can be read here.
Scott just responded here, with a number of points relevant to the topic of rationalist communities.
I am interested in what LW thinks of this.
Obviously, at some point being polite in our arguments is silly. I'd be interested in people's opinions of how dire the real world consequences have to be before it's worthwhile debating dishonestly.