Sept. 11th a Conspiracy? Yeah, Right...

Those of you that believe that the events on Sept. 11th were created by our own government are paranoid. Please help me to understand how you came to this conclusion. I'd very much like to know why the CIA (or other gov't agency) would stike the economy in such a way. Just don't tell me that it was to create a reason to go to Iraq. That would be as far fetched as the idea itself.