What it is about is tribe, which is what makes all that conflation of racism and bigotry with political difference so amusing. Political prejudice is not the moral equivalent of racial prejudice, but they operate in very similar ways, as anybody who ever has spent much time around a genuine racist or anti-Semite knows. Taxes too high? Blame the blacks. Not making enough money? Blame the Mexicans. Foreign policy seem overwhelmingly complex? Blame the Jews. Whataburger gave you a full-on corn-syrup Coke instead of a Diet Coke? Blame the blacks, Mexicans, Jews, subcontinental immigrants . . . somebody. Racism and anti-Semitism are metaphysical creeds, and those who adhere to these creeds see the work of the agents of evil everywhere. For them, there is no world outside race and racism.

In this, they are very similar to the Hillary Clinton–voting Manhattan balletomanes who seethe that they must endure being seated in the David Koch theater. David Koch’s brand of libertarianism is mild and constructive, and it has about as much to do with ballet as Keith Olbermann has to do with astrophysics. But for the fanatic, even to hear the name spoken is unbearable.

Imagine being so mentally poisoned and so spiritually sick that you feel the need to organize a protest at New York–Presbyterian Hospital because the institution accepted $100 million — the largest gift in its history, being put to purely philanthropic health-care purposes — from someone whose political views are at odds with your own. Imagine what it must be like to feel that doing that is a moral imperative. Imagine sitting down to listen to a Beethoven string quartet and being filled with paralyzing anxiety that the cellist might not share your views on the Arab–Israeli conflict.