Information, Inequality, and Mass Polarization: Ideology in Advanced Democracies

Growing polarization in the American Congress is closely related to rising income inequality. Yet there has been no corresponding polarization of the U.S. electorate, and across advanced democracies, mass polarization is negatively related to income inequality. To explain this puzzle, we propose a comparative political economy model of mass polarization in which the same institutional factors that generate income inequality also undermine political information. We explain why more voters then place themselves in the ideological center, hence generating a negative correlation between mass polarization and inequality. We confirm these conjectures on individual-level data for 20 democracies, and we then show that democracies cluster into two types: one with high inequality, low mass polarization, and polarized and right-shifted elites (e.g., the United States); and the other with low inequality and high mass polarization with left-shifted elites (e.g., Sweden). This division reflects long-standing differences in educational systems, the role of unions, and social networks.