Traditionally, sociologists have tried to understand social life as a structured system of institutions and norms that shape individual behavior from the top down. In contrast, a new breed of social modelers suspect that much of social life emerges from the bottom up, more like improvisational jazz than a symphony orchestra. People do not simply play parts written by elites and directed by managers. We make up our parts on the fly. But if everyone is flying by the seat of their pants, how is social order possible? The puzzle is compounded by scale. Coordination and cooperation are relatively easy to attain in a jazz quartet, but imagine an ensemble with millions of musicians, each paying attention only to those in their immediate vicinity. Without a Leviathan holding the baton, what prevents the population from descending into a Hobbesian cacophony of all against all?

Social life from the bottom up

New and compelling answers to this question are being uncovered by social theorists using an innovative modeling tool developed in computer science and applied with impressive success in disciplines ranging from biology to physics – agent-based computational (ABC) modeling.

ABC models are agent-based because they take as a theoretical starting point a model of the autonomous yet interdependent individual units (the “agents”) that constitute a dynamic system. The models are computational because the individual agents and their behavioral rules are formally represented and encoded in a computer program such that the dynamics of the model can be deduced using step-by-step computation from given starting conditions.