Robust Communication through Mixed Messages

Current Version ArXiv: 2403.13983

Summary: I explore how non-material incentives and heterogeneity affect strategic communication, specifically in settings where the sender and receiver have nearly independent preferences.

The case where preferences are exactly independent is  knife-edge: communication is 'theoretically' possible, but vanishes with slight heterogeneity. Communication can be restored by 'nudging' preferences to be slightly state-dependent in a compatible manner. I characterize communication in this setting through graph-theoretic representations of equilibria called communication graphs. Compatibility restricts these communication graphs to be acyclic and connected, and requires compatibility between the graph and the dependence in the sender's preference.

Sympathy (ie. aligning preferences) promotes communication in quantitative settings, but can impede communication in similar 'qualitative' settings. Money-burning (e.g. advertising) can be a powerful persuasion tactic in the latter cases.  

Ripple Effects and Norms

Current Version

Summary: I explore how even slight altruism can ground pro-social norms in large societies through a mechanism of social influence. Higher strategic homogeneity results in more stable norms.

I model a large anonymous society where individuals repeatedly face a dilemma between acting selfishly or contributing to social surplus. If agents care even slightly about the social surplus then pro-social norms can be sustained through a desire to set an example for others. 

In contrast to other models of cooperation in this setting, these norms can be robust to a sub-population of purely selfish actors. There are a continuum of robust equilibria, more robustness equilibria are associated with higher strategic homogeneity.

Increasing the publicity of bad actions does little to increase the robustness of equilibria.

(Ab)using Indifference: Purification in Communication and Repeated Games

Current Version ArXiv:2602.23098

Summary: I define an abstract technique of 'abusing indifference' used to tractably analyze communication and repeated games. I show the resulting equilibrium are fragile to any heterogeneity. 

This has severe implications for pure equilibria of repeated games with imperfect monitoring — generally limiting the equilibria the perfect public equilibria. I show some 'abusing indifference' equilibria can be understood as approximations of mixed strategy 'reputation' equilibria.

Inequality and the Erosion of Norms

Summary: Empirical studies show that altruism is linked to an individual's wealth. Using this fact to enrich the Ripple Effects model, I show that inequality has a pernicious effect on norms, and that unbalanced growth erodes norms despite increasing altruism.