Modeling the size of wars: From billiard balls to sandpiles

Richardson's finding that the severity of interstate wars is power law distributed belongs to the most striking empirical regularities in world politics. This is a regularity in search of a theory. Drawing on the principles of self-organized criticality, I propose an agent-based model of war and state formation that exhibits power-law regularities. The computational findings suggest that the scale-free behavior depends on a process of technological change that leads to contextually dependent, stochastic decisions to wage war.