Persuading Voters

Abstract

In a symmetric information voting model, an individual (politician) can influence voters' choices by strategically designing a policy experiment (public signal). We characterize the politician's optimal experiment. With a nonunanimous voting rule, she exploits voters' heterogeneity by designing an experiment with realizations targeting different winning coalitions. Consequently, under a simple-majority rule, a majority of voters might be strictly worse off due to the politician's influence. We characterize voters' preferences over electoral rules and provide conditions for a majority of voters to prefer a supermajority (or unanimity) voting rule, in order to induce the politician to supply a more informative experiment. (JEL D72, D83)

Expert advice to a voting body

“…Lemma 1 implies that if (σ, v * , {µ s } s∈Ω ) is a persuasive equilibrium then µ s ∈ W D for all s in the support of σ. The following result, which follows from arguments similar to Kamenica and Gentzkow (2011) as well as concurrent work by Alonzo and Câmara (2015), establishes that such a signaling strategy is possible if and only if the prior distribution is in the convex hull of W D . Throughout the proof, Co(·) refers to the convex hull of a set.…”

“…Kamenica and Gentzkow derive conditions under which there exists a signal that benefits the sender and discuss optimal signals from the perspective of the sender. Alonzo and Câmara (2015) extend this framework to a setting in which multiple receivers make decisions by voting. These public signals, like the expert communication in my model, can make a majority of voters strictly worse off.…”

Bayesian persuasion with heterogeneous priors

“…Step 2: Compute the pooling values ∆ (1,2) , ∆ (2,3) and ∆ (3,1) . If all values are (weakly) negative, then a fully informative experiment is optimal.…”

“…With the program, the government has more flexibility and control to uncover hard information to persuade bureaucrats. 2 After the initial success of the program, the BIT now "permeates almost every area of government policy," and are setting up similar programs in Australia, Singapore, Germany and the US (Rutter, 2015).…”

“…For simplicity, let the politician's payoff be a, which is the bureaucrat's effort to 2 In a recent interview, David Halpern (chief executive of BIT) said, "If you're a permanent secretary or head of department [,] you have seen lots of ideas come and go. New governments come in on a wave of new shiny ideas.…”