Socio-economic segregation and the new cleavage

There is some evidence that citizens in advanced democracies are increasingly segregated on exactly those dimensions that form the social basis of the new cleavage. This study examines the interrelation of these developments by studying individual political attitudes and behaviour as a function of the group-based social networks in which people are embedded. Using both publicly available datasets and original survey data from the US and the Netherlands, and focussing on education and social class, I examine two questions. First, have social networks indeed become more homogeneous, and more aligned, based on education and social class? Second, is social network heterogeneity predictive of group-based attitude extremity, constraint, affective polarization, and voting? I study the first question with repeated cross-sectional surveys over a period of two decades. For the second question, I use both cross-sectional data and two natural experiments. The experiments leverage quasi-random assignment to classrooms within schools, and variation in conscription reforms, to test whether exposure to heterogeneous environments during one’s impressionable years causes more heterogeneous networks, and in turn more political moderation. Taken together, results will inform debates on cleavage crystallization and processes of social closure.