A related problem in society is the assumption of ignorance; if someone expresses a passionate opinion and you demur, it seems more and more common for your interlocutor to assume you don't know some key fact in their worldview rather than solicit the basis of your disagreement. Of course you can use this to your advantage, insofar as it's easier to get people to give you information by expressing disagreement than by asking questions.

http://meta.wikimedia.org/wiki/Cunningham's_Law