Computational simulation as theoretical experiment

Abstract

Agent-based simulation can help establish the possibility and characteristics of emergent processes. However the simulation is meaningless without an accompanying interpretation. We argue that the original context needs to be carried with the simulation so as to limit excess generalization from such models. The simulation becomes a theoretical experiment which mediates between observations of the phenomena and natural language descriptions. Replication and exploration of simulations can start to identify the extent of their validity, and thus pave the way for cautions and limited generalization of results. This is illustrated by reimplementing and re-examining two established models. Schelling's model of racial segregation is shown to give counter-intuitive results when pushed out of its intended context—the domain of valid interpretation is narrower than that covered by the whole the model. Takahashi's model of generalized exchange is shown to have included unnecessary assumptions. In this case the domain of valid interpretation is wider than the model (at least in this aspect). A tag-based variation is described where generalized exchange is shown to emerge without information about the past behavior of others.