Political awareness, microtargeting of voters, and negative electoral campaigning

In modern elections, ideologically motivated candidates with a wealth of information about individual voters and sophisticated campaign strategies are faced by voters who lack awareness of some political issues and are uncertain about the exact political positions of candidates. We study to what extent electoral campaigns can raise awareness of issues and unravel information about candidates' political positions. We allow for microtargeting in which candidates target messages to subsets of voters. A candidate's message consists of a subset of issues and some information on her political position in the multi-dimensional policy subspace spanned by this subset of issues. The information provided can be vague, it can be even silent on some issues, but candidates are not allowed to bluntly lie about their ideology. Every voter votes for the candidate she expects to be closest to her but takes into account only the subspace spanned by the issues that come up during the campaign. We show that any prudent rationalizable election outcome is the same as if voters have full awareness of issues and complete information of policy points, both in parliamentary and presidential elections. We show by examples that these results may break down when there is lack of electoral competition, when candidates are unable to use microtargeting, or when voters have limited abilities of political reasoning. Allowing for negative campaigning restores the positive results if voters' political reasoning abilities are limited. It can even be achieved with just public campaign message in the presidential elections while parliamentary elections still require microtargeting of voters.