"The official 9/11 story must be true because a secret operation of this scale would have been discovered by now."
Here are a few of the many responses to that assumption from critics of the official 9/11 story:
1) The secret operation has been discovered, and it was discovered on day one. It is incorrect to assume that this discovery would be covered in the main stream media, which refuse to even mention that questions exist.
2) False-flag terror works by conducting the terror through the bureaucracy under the guise of a "drill", keeping the honest and loyal workers who are actually carrying out the terror off the trail of deceit. This is exactly what happened on 9/11.
3) Covert operations are run on a need-to-know basis. The operation of 9/11 would not require "thousands of people" as suggested by followers of the official story. It could have been accomplished by a very small number of individuals who were actually involved in the planning. [click here] and [click here] for two explanations.
4) By definition, we are unaware of U.S.-sponsored covert operations that have successfully remained secret. It is therefore meaningless to conclude that such covert operations are always exposed.
5) Many covert operations run by the U.S. government have remained secret for years, including the fraudulent Gulf of Tonkin incident, warrantless wire-tapping by the NSA after 9/11, the Manhattan Project, and the Tuskegee Syphilis experiment, to name only a few.
6) The 9/11 terror attacks are the greatest crime ever committed in the history of the United States. The stakes involved are clearly incomparable to the stakes involved in other covert operations, and therefore the players involved (of whatever small number) are more committed to maintaining the secrecy.
7) Hard evidence indicating government complicity in 9/11 must be given precedence over the unsupportable assertion that claims of government complicity never need to be considered unless they are exposed on the evening news. Such an assertion is simply a self-fulfilling prophesy.
(For another treatment of the difficulty some have in considering the evidence, see this article by Morgan Reynolds.)