Conspiracy Theory
Apart from being a second-rate film staring Mel Gibson, conspiracy theory is the term applied to any thinking about manipulation outside the normal bounds of discourse. Now some theories are worthy of the derision this label provokes - such a David Ikes ratings or L Ron Hubbard's BS about aliens in Dianetics. In any case here is a top post on kuro5hin.org that details one such theory:
Astute observers of history are aware that for every notable event there will usually be at least one ,often several wild conspiracy theories which spring up around it. "The CIA killed Hendrix" " The Pope had John Lennon murdered ", "Hitler was half Werewolf", "Space aliens replaced Nixon with a clone" etc,etc. The bigger the event, the more ridiculous and more numerous are the fanciful rantings which circulate in relation to it.

So its hardly surprising that the events of Sept 11 2001 have spawned their fair share of these ludicrous fairy tales. And as always, there is - sadly - a small but gullible percentage of the population eager to lap up these tall tales, regardless of facts or rational analysis.

One of the wilder stories circulating about Sept 11, and one that has attracted something of a cult following amongst conspiracy buffs is that it was carried out by 19 fanatical Arab hijackers, masterminded by an evil genius named Osama bin Laden, with no apparent motivation other than that they "hate our freedoms...."