An evolutionary model for the development of trust in democracies

Political scientists have recognized the importance of trust, norms, and political culture in democratic governance, but have not come up with a general theory explaining how it is possible that trust and trust-promoting institutions develop in spite of adverse incentives. Untrustworthy actors will find ways to avoid weakly established norms and institutions, and previous theories of institutions promoting trust did not have an explanation for why these norms solidified at all. This thesis uses the idea of co-evolution to show that if weak trust and weak institutions develop together, they can mutually reinforce and overcome countervailing pressures. I present a mathematical model for the development of trust in democracies, based on stochastic evolutionary game theory. I show that a two-level evolutionary process is sufficient to explain the development and maintenance of trust between actors in government. At the lower level, the agents and citizens of the democracy learn to trust one another; at the upper level, society develops institutions which encourage that trust. The institutions in question identify and broadcast which actors are trustworthy. Broadcasting that information allows trustworthy actors to identify one another and exclude untrustworthy actors. The benefit that such institutions give to trustworthy actors enables trust to spread. The model explains aspects of democratic consolidation and backsliding. Adherence to the rules of democracy ultimately depends on mutual toleration between important office-holders, but they face structural incentives to arrogate power rather than cooperating for the good of democracy. Nevertheless, established democracies work and have cooperative governments; this is possible because of evolved trust in these democracies. The model explains why democratic erosion tends to come from outsider parties and insurgent candidates. Endorsement by an establishment party is a signal of a candidate’s trustworthiness, but this is not so for outsider parties.