we don’t really have to wonder what it’s like to live in a tribal society anymore, do we? Because we already do. Over the past couple of decades in America, the enduring, complicated divides of ideology, geography, party, class, religion, and race have mutated into something deeper, simpler to map, and therefore much more ominous. I don’t just mean the rise of political polarization (although that’s how it often expresses itself), nor the rise of political violence (the domestic terrorism of the late 1960s and ’70s was far worse), nor even this country’s ancient black-white racial conflict (though its potency endures).