It seems our long evolutionary history has favored group solidarity. Empathy and cooperation within the group; distrust and aggression toward those outside.
The first groups were those of kin, tribes, and then ethnicity. As societies grew, groups identified themselves in more complex ways. Some researches would suggest that religions evolved as group adhesives.
WE are moral, beautiful, enlightened, favored by God. THEY are wicked, ugly, ignorant, blighted by Providence.
Red state and blue state. The 99% and the 1%. Black and white. Christian and Muslim.
I mean, admit it. WE are the best. It’s commonsense.
Meaning, common sense.
In the final comments of his lectures on literature, delivered at Wellesley and Cornell in the 1940s-50s, Vladimir Nabokov had some things to say about common sense and human conflict:
It is instructive to think that there is not a single person in this room [he told his students], or for that matter in any room in the world, who, at some nicely chosen point in historical space-time would not be put to death there and then, here and now, by a commonsensical majority in righteous rage. The color of one's creed, neckties, eyes, thoughts, manners, speech, is sure to meet somewhere in time or space with a fatal objection from a mob that hates that particular tone. And the more brilliant, the more unusual the man, the nearer he is to the stake. Stranger always rhymes with danger.Nabokov, who had first fled Russia from the Bolsheviks, then Germany from the Nazis, was urging his students to eschew any form of group self-righteousness, and to cultivate instead imagination, memory and an artistic sense. The best temperament for resisting the siren call of the group, he said, is a combination of artistic and scientific.