Social cohesion is an important prerequisite for the health of democracies. In this chapter, we consider how political norms of competition in democratic settings can become detrimental to societies afflicted by affective polarization by deteriorating social trust and tolerance and increasing social discrimination. We theorize that the deterioration of social cohesion will follow as partisan identities become ever more relevant criteria in people's social categorization of themselves and others, thereby strengthening political norms of competition and potentially overpowering social norms of cooperation. We discuss the theoretical foundations of this argument, provide some empirical evidence of the underlying mechanism using data from five countries, and identify some limitations and avenues for future research.
