U.S. congressional roll-call voting records show that as polarization of the two parties along the economic dimension changes, polarization along the social/cultural dimension tends to change in the opposite direction. A model of party competition within a two-dimensional ideology space is developed in which party platforms are determined by voters who compose the party. It is shown that if distribution of voter preferences is radially symmetric, polarization of party ideologies along the two dimensions are inversely related, as observed. The model gives a remarkably good quantitative account of the historically observed movements in polarization along the two dimensions.View the Full Working Paper
The Changing Polarization of Party Ideologies: The Role of Sorting
WP 23-07 – History shows that when political parties become more polarized along one dimension of policy, they become less polarized along some other dimension. We explain how this can happen via changes in the ideological makeup of parties.