Title: Explaining Parochialism: A Causal Account for Political Polarization in Changing Economic Environments,
Abstract: Political and social polarization are a significant cause of conflict and
poor governance in many societies, thus understanding their causes is of
considerable importance. Here we demonstrate that shifts in socialization
strategy similar to political polarization and/or identity politics could be a
constructive response to periods of apparent economic decline. We start from
the observation that economies, like ecologies are seldom at equilibrium.
Rather, they often suffer both negative and positive shocks. We show that even
where in an expanding economy, interacting with diverse out-groups can afford
benefits through innovation and exploration, if that economy contracts, a
strategy of seeking homogeneous groups can be important to maintaining
individual solvency. This is true even where the expected value of out group
interaction exceeds that of in group interactions. Our account unifies what
were previously seen as conflicting explanations: identity threat versus
economic anxiety. Our model indicates that in periods of extreme deprivation,
cooperation with diversity again becomes the best (in fact, only viable)
strategy. However, our model also shows that while polarization may increase
gradually in response to shifts in the economy, gradual decrease of
polarization may not be an available strategy; thus returning to previous
levels of cooperation may require structural change.