You're right, you have to have some facts before you can reason, and once you've listed something in your fact file, it's hard to talk yourself into re-evaluating it.
Did you ever see "Galaxy Quest"? It's a spoof on Star Trek, and how all the actors are famous only in the fact that they were on that show, not that they were great actors or went on to any other great things. There's a part in it where some die-hard fans want to discuss with the "captain" some minutia about the control mechanism built into his chair. They contrast the controls usage in one show with the same control in another show. They want him to resolve the contradiction.
That 'quest' world was real to them, and any excuse he offered would have been acceptable. Real Star Trek actors have spun tales to explain away supposed contradictions in their show, to the satisfaction of fans.
Once you've defined your universe -- Star Trek, Lord of the Rings, or Jehovah's Bringin' Somethin' Better -- you'll tend to believe anything that supports it.
Once I finally got my head around that, I was able to start the process of breaking free. (But I still believe in Hobbits, and nobody's tellin' me otherwise!)
-Dave