Paul Krugman: In-Crowd Economics: It's Hip to Fear the Deficit 

Back during the early days of the Iraq debacle, I learned that the military has a term for how highly dubious ideas become not just accepted, but viewed as certainties.

"Incestuous amplification" happens when a closed group of people repeat the same things to each other — and when accepting the group's preconceptions itself becomes a necessary ticket to being in the in-group. A fundamentally flawed notion — say, that the Germans can't possibly attack though the Ardennes — becomes part of what everyone knows, where "everyone" means by definition only people who accept the flawed notion.