Exploring the Psychological Foundations of Ideological and Social Sorting

Americans are sorting ideologically: Liberals and conservatives are more likely to respectively identify as Democrats and Republicans. They are sorting socially as well: Partisans like and trust copartisans more than opposing partisans. Existing explanations for these phenomena rely on exogenous factors, such as elite polarization. But exogenous explanations cannot fully explain variation in sorting. We argue that psychological characteristics...