Groups activate identities; identities activate behavior: How political homogeneity breeds extremism and apathy in American politics

Dominant accounts of partisan polarization in political science and psychology posit that misunderstandings and mutual animosity drive conflict between Democrats and Republicans. Despite such high-profile tension, many Americans remain disengaged from politics. Using Identity Theory in sociology, we account for both rising polarization and persistent disengagement by turning attention to internal party dynamics. Partisan politics operates differently, depending on the political makeup of commonplace fixed social groups like sets of friends and coworkers. Partisan politics creates relatable common ground when social groups are politically homogeneous but creates tension in politically diverse small groups. Under these conditions, social similarity fosters more political activity generally (both normative and extreme), while deterring political engagement among those in politically diverse groups. Analyses of an original quota-sampled survey and a representative panel survey support expectations. Political homogeneity strengthens political identities, which produces more role-typical behaviors and extreme attitudes. These findings show how the desire to preserve relationships increases polarization, while also maintaining political disengagement.