Simulations (System Dynamics and Agent-Based Models)

I have been always interested in social phenomena conceived as complex systems. Systems are entities that consist of multiple parts, which interact with each other in multiple ways. Systems also interact with their environment. Interactions between parts of a systems and between a system and the environment may result in a system’s capacity to self-regulate itself via corrective mechanisms. Some systems are resilient (they tend towards stability) while others are not (they tend towards chaos).

Social systems consist of entities (e.g., individuals or firms) that interact with each other in various ways. The effects of social interactions feed back to the social entities themselves (i.e., social systems exhibit recursiveness). The flow of interaction between social entities is dependent on initial conditions (i.e., social systems exhibit path dependency). Social entities may come in different forms and shapes (i.e., a social system is heterogeneous). The effects of social interaction reverberate at higher levels of analysis (e.g., group behaviour or industry performance). Unexpected aggregate behaviour is possible (i.e., a social system exhibits emergence in aggregated behaviour with respect to individual conduct).

Thomas C. Shelling provided one of the earliest examples of the design, dynamics and results of a social system. Urban environments often exhibit segregation between social groups (e.g., by ethnic origin, by income, etc.). A question arises about why segregation happens, provided that no central authority coordinates where individuals live. Shelling argued that relatively simple decision-making rules at the individual level (e.g., that individuals like to live close to other individuals who are similar to themselves) trigger patterns at the aggregated level, which result in the segregation between social groups (Schelling, Thomas C. “Dynamic models of segregation.” Journal of Mathematical Sociology 1.2 (1971): 143-186.)

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