My friend and coworker asked me the other day:
“Why do these people hate each-other so passionately?”

“Because they are rational. They have reached their present convictions as the result of a rational process. Hence they are convinced they are absolutely right. Then, when anybody expresses a different opinion, they interpret ‘dissent’ as a personal attack. My ‘truth’ having been reached in a rational manner means that all other opinions must be false. Defending them – against all ‘evidence’, means that these people are either provocative or, even, outright destructive.”

“But being rational doesn’t include being open to the possibility of being wrong?”

“I’ll have to rephrase. ‘They are convinced they are acting in a rational manner’. In fact, we, humans, are ‘rationalizing’ rather than ‘thinking rationally’. We use whatever arguments/information we have at our disposal to justify whatever conviction we already harbor. And only when reality slaps us in our faces we ‘open up’. Even science and justice work out this way.
“Innocent until proven guilty”. Only scientists and law-enforcers are already accustomed to the possibility that things may not be exactly as they previously thought they were. Politically minded people are still learning.”