common-sense systemic bias
Common sense shows that the U.S would have major geo-politcal motives for orchecstrating the 9/11 attacks. You will agree that the occuaption of the oil-rich country of Iraq,the extension of U.S military presence in Afghanistan [which provides America with a certain amount of significance in the Indian Subcontinent (a highly important area in terms of political significance)] will be enough motive for the U.S to fake the "terrorist attacks" on 9/11.