Mechanism Design with Informational Punishment

Abstract

We introduce informational punishment to the design of mechanisms that compete with an exogenous status quo: A signal designer can publicly communicate with all players even if some decide not to communicate with the designer. Optimal informational punishment ensures that full participation in the mechanism is optimal even if any single player can publicly enforce the status-quo mechanism. Informational punishment restores the revelation principle, is independent of the mechanism designer's objective, and operates exclusively off the equilibrium path. Informational punishment is robust to refinements and applies in informed-principal settings. We provide conditions that make it robust to opportunistic signal designers.