I diagnose the deterioration of public discourse regarding basic facts to the rise of populist politics, which is powered by the activation of identity-based fear and resentment of other groups. Populist politics “hears” the factual claims of other groups as insults to the groups it mobilizes, and thereby replaces factual inquiry with modes of discourse, such as denial, derision, and slander, designed to defend populist groups against criticism and whip up hostility toward rival groups. Nonpopulist groups, in turn, add fuel to the fire by blaming and shaming those who seem stubbornly and ignorantly attached to false claims in defiance of evidence.