A very interesting post jwfacts. Certainly a well known theorist on the psychology of personality, George Kelly, spoke of humans obtaining truth for themselves by means of what he called constructive alternativism. He purported that everyone had their own individual constructs based on their own experiences and perspectives. The more these constructs lined up with our experiences the the more they were reinforced. Therefore if both you and defd find that in your lives the contructs you have are consistent you will be unlikely to abandon them. However, since you have opposite views it is likely that were you to switch lives you might find your constructs changing accordingly. Constructs thus have a value to each person in that specific time and place.
He also determined that your constucts influence your experiences and perceptions of these. Thus a higher degree of incongruence is needed in order to shake someone's belief that what they hold to be true is in fact actually true.