The issues of logic and intellectual prejudice fascinate me, but I have never studied them.
I have seen a lot of people who will refuse to concede an opinon/point even with huge amounts of evidence (even smoking guns) against them. I think one way to get past this is to make bets with substantial amounts of money on the outcome. If someone puts their money on it, then they REALLY beleive it. Not just "want it to be true".
look at the amateur statistician WM Briggs. I remember him saying that he thought it more likely than not that McCain would win in 08 (about a week before the election). I told him I would put several thousand on a bet with him (Tradesports had it at 85% that Obama would win at that point). He refused. The bizarre thing is that WM is a Bayesian!
I think wagers would just heat things up. You're totally right about a lot of people sticking to a certain position though. They are either motivated by the need to "win" or to protect the particular idea. That trumps being right. I see it all the time.
You make a good point on the 2nd one as well. You get to see what people know is right deep down vs what they want to believe. Faith healing, Christian scientists (The religion, not scientists that believe in Jesus), and alternative medicine are good examples. The vast majority will go to a real doctor when it gets serious. There are some true believers who let their kids die though. Luckily there aren't very many.
I think many people believe in belief more than any specific belief. People switching religions for non-religious reasons is a good example. How much could a Christian REALLY have believed in Jesus if they convert to Judaism, for example, for purely external reasons?
On the other hand you could make the argument that a strong emotional experience, like planning to get married, may be enough to overcome the emotional attachment the lymbic system has with the original idea. The strong love feelings plus the positive reinforcement and frequent exposure to the new belief system could make that an acceptable replacement. The cerebral cortex in people like that will just rationalize what the lymbic system wants.
It is pretty interesting.