A Model of Censorship and Propaganda

Abstract: A fundamental constraint of information design is that propaganda must be believed to be effective. The presence of outside information tightens this constraint. We extend the canonical model of Bayesian persuasion to endogenize the presence of such information. The sender (government) chooses both the precision of an outside signal—it chooses a level of censorship—and a probability distribution over propaganda messages, where the distribution can be conditioned on the outside signal. The government bears an opportunity cost of censorship, in that the government relies on outside information to decide whether to repress rather than persuade. In equilibrium, the government employs both censorship and propaganda, but only if the citizen is ex ante close to indifferent between taking and not taking the action desired by the government. In this region of the parameter space, censorship and propaganda are perfect substitutes.