Prime directive

In his classic Sci-Fi book, I, Robot, Asimov has one of the technicians observe the following: "He (the robot) believes only reason, and there's one trouble with that..." his voice trailed away.
"What's that?
"You can prove anything you want by coldly logical reason--if you pick the proper postulates."
The reason many people cannot discuss religion or politics is that each side has a different postulate. If your postulate (your fundamental starting point, your conviction that you never yield on) is a slogan "Government is the problem, not the answer," you will always come to conclusions that flow from that. The reason "big lie" propaganda works is that once you establish the postulate, data does not matter.
Some Christians believe "Every word of the bible is literally true." They shed science and historical data like an ill-fitting garment, and they embrace physical impossibility like an affectionate child-- all because of their postulate.
Our Enneagram style functions like a postulate, in a moderate softened sense. If I am a style Nine,my postulate is that I MUST have harmony. If I am Three,I MUST have success. The more neurotic I am, the more rigid and determining is my postulate.
The postulate filters out all information that conflicts with it and suggests that all responses lead to it. If I am a Four, I filter out all (or at least most) suggestions that I am just one of the folks and I respond in such a way that reinforces my belief that I am unique and not quite acceptable in my uniqueness.