Identity competition and social change

How does identity competition slow the spread of social innovations? I develop a simple model showing that identity polarization fosters homophilic networks, which reinforce group norms and hinder behavioral change. Testing this mechanism with newly constructed data on over 16 million Dutch families (1812–1920), I exploit the 1853 restoration of the Catholic hierarchy as a shock to religious competition. Polarization, measured through first-name choices, is linked to slower adoption of fertility control and stronger adherence to religious norms, particularly in tightly knit communities – as measured in marriage witness networks. These findings demonstrate how identity competition can trap social groups in traditional practices, even as other segments of society modernize.