Friendship as a Social Process: an Agent-based Model Grounded on Lazarsfeld and Merton’s Homophily Theory

Since the publication of "Friendship as a social process” by Merton and Lazarsfeld, homophily theory has been widely used in contemporary empirical research. In that essay, the authors formulate some counterfactual hypotheses, and conduct a thought experiment to explain the tendency for some actors to make friends with similar others, supposing 800 social actors linked together by 400 social ties. Using the NetLogo language, in order to formalize such thought experiment, we develop an agent-based model grounded on Lazarsfeld’s description of the system of action. If we perform dynamically the process suggested in that work, and pursue the micro foundation of the social action, we observe the evolution of the process through the four typological categories of social ties developed by Lazarsfeld. We implement four scenarios, each representing a specific combination of authors’ hypotheses. The results allow us to clearly observe four different emerging social patterns that are generated from the micro level by the interaction between individual agents who follow the mechanisms inspired by the original formulation of the theory. Through these simulations, we can examine the unexpected effects - on a system of action – caused by the introduction of Lazarsfeld and Merton’s hypotheses.