First watch this video.
Politics and polarization have obviously gotten very bad and are getting worse by the day, not only in the United States but also in the rest of what has historically been called "western civilization." Tribal behaviors are primitive in the sense that they are entirely instinctually driven, so those engaging in these behaviors are never aware that they are doing so. These unconscious behaviors can be overridden over time, but only with great effort and only rarely. The rules below are for non-tribal observers who want to understand what they're looking at.