I've been saying for a while that this is just Doublethink or avoidance of ThoughtCrime. These people can refuse to believe that which is obvious if they have been told to. It is really that simple. I spent two days trying to convince two such good outer party members that the USA allowed the Pakistani ISI to evacuate Taliban and Al Quaeda. The incident was well documented. I posted three stories (AP, NYT, WSJ) and another guy on the thread posted a fourth (MSNBC) all confirming that it happened. But instead of accepting that this happened or even that it COULD have happened, they chose to believe bald assertions from the FedGov.
In sum, they believe everything. They cannot not believe everything because they have been conditioned to believe everything and they want to believe everything. They love Big Brother.