Communicating on electoral platforms

This paper proposes an analysis of strategic communication on platforms by candidates during an electoral campaign. A candidate's platform in a (possibly) multidimensional policy space is fixed, but is imperfectly known by voters. A candidate strategically decides the emphasis he puts on the various issues, and thus the precision of the information he conveys to voters on his position on each issue. We show that if voters are fully rational, then all the relevant information is revealed at equilibrium, whatever the candidate's true position. We then study a model of boundedly rational voters, who take at face value the messages sent by the politicians, without being able to decipher their strategies. If voters are boundedly rational in this sense, a politician will not transmit all the relevant information; his communication strategy will depend on both the prior in the electorate and his true positions (unknown to the electorate). In particular, we show that candidates address all issues with positive probability, but tend to talk more often on issues on which they are a priori congruent with the representative voter, thereby providing a "nuanced" version of Petrocik's "issue ownership theory".