Social scientists who study conflict say the only way to understand it — and to begin to get out of it — is to look at the powerful currents of human emotions that are the real drivers. They include the fear of not belonging, the sting of humiliation, a sense of threat — real or perceived — and the strong pull of group behavior…

Add to all of that leaders who stoke the conflict, and disagreements over the simplest things can become almost sectarian.

Eran Halperin, a social psychologist at the Hebrew University of Jerusalem in Israel who studies emotions in conflict, said that people in intractable fights often do not remember how they started but that they are perpetuated by a sense of group threat. One’s group — for example, American or Christian — is an extension of oneself, and people can become very defensive when it — or its status in a hierarchy — changes.

“If my American identity is an important part of who I am, and suddenly there’s a serious threat to that, in some ways that means I don’t know who I am anymore,” he said. “It’s an attack on the very core of how I see myself, of how I understand myself.”