Eliciting the deserving winner in the presence of enemies

Abstract

We analyze the problem of a jury that has to select the deserving winner from a group of candidates when (i) the identity of the deserving winner is known to all jurors but not verifiable, (ii) each juror identifies with a different candidate whom they want to favor, and (iii) some jurors may have enemies among the candidates whom they want to harm. We introduce a necessary condition relating to the jurors’ enemies for implementing the deserving winner, called minimal impartiality. The mechanisms proposed in the literature to implement the deserving winner via backward induction fail when jurors have enemies, even though minimal impartiality is satisfied. We propose a simple sequential mechanism that successfully implements the deserving winner via backward induction, whether the jurors have enemies or not, as long as minimal impartiality is satisfied.