An Epidemic Model of Violence and Public Support in Civil War

Abstract

How do civilians respond to violence in civil war, and how do these responses shape combatants’ coercive strategies? Conventional wisdom expects civilian victimization to backfire, as a security-minded public “balances” against the side posing the greatest threat to its livelihood and survival. Yet combatants often expect a terrorized population to do the opposite, “bandwagoning” with those most willing and capable to inflict harm. Using an epidemic model of popular support dynamics, I explore the logic of balancing and bandwagoning in irregular civil war. I argue that when civilian strategy is clearly communicated to combatants, civilians are always better off balancing, and combatants are better off avoiding punishment. When civilian choice is not observed, the balancing equilibrium breaks down and patterns of violence depend on the local balance of power. The model’s results challenge the view that selective violence is most common in areas of incomplete control. Due to uncertainty over civilian behavior, violence in both divided and perfectly controlled areas can occur in equilibrium, inflicting great costs on civilians. I compare these predictions against the historical record of Soviet counterinsurgency in Western Ukraine, using new micro-level data from the declassified archives of the Soviet secret police.