The story that the CIA destroyed interrogation tapes is a ruse.
This yummy little mind-snack serves as a dynamo that helps power the Al-Qaeda illusion. (The Sibel Edmonds story is another little engine that could.)
The CIA story naturally conjures in our minds horrible imagery of torture. The assumptive close hidden in this imagined torture is that there really must exist a terrible enemy indeed, if we must stoop to such heinous activities just to protect ourselves.
In other words, the story of the destroyed tapes has in it the assumptive close that Al-Qaeda even exists.