Hardwired Tribalism
I was recently part of a rather odd Usenet exchange. Someone had suggested that if Gore had been elected in 2000 he might, like Bush, have ended up invading Iraq. A poster who appears to be a committed partisan of the Democratic party objected that that was nonsense. I offered as evidence that it wasn't nonsense Clinton's cruise missle attack on a pharmaceutical factory in the Sudan, which was a sort of miniature of the Iraq invasion—responding to a terrorist attack by attacking a nation that had no obvious connection to it, with a bogus claim of weapons of mass destruction as justification.
The Democratic poster leaped to the conclusion that I was a Bush supporter, maintained that conclusion even after I explicitly denied it, and went through various contortions in order to avoid conceding that I hadn't said what he claimed I had said—he had converted my "response to 9/11" into "justified response to 9/11." His behavior struck me as particularly odd given that "Clinton behaved just as badly as Bush" is not an argument one would usually expect a Bush supporter to make—quite aside from various other unkind things about Bush I had said in other posts.
The only sense I could make out of it was that I was encountering a tribalistic view of the world. There are two sides, everyone who isn't on my side is on the other side, hence anyone who says something negative about the Democrats must be a partisan of the Republicans and any evidence to the contrary is to be ignored as experimental error.
Not long after, I heard a radio report about the French government caving in to the demands of demonstrators that they rescind legislation making it possible for employers to fire young workers. Oddly enough, part of my reaction was a feeling of satisfaction. The news implied a further decline of the wealth, power, and status of France, France is part of Europe, Europe is at the moment the obvious status rival to America, and I am an American. Speaking as an economist, my best guess is that the decline of the French economy makes me worse off, not better off. But to some part of my mind hardwired by hundreds of thousands of years of evolution in hunter/gatherer bands, there is only us and them, and anything that is bad for them is good for us.