Arguing about Voting Rules
Résumé
When the members of a group have to make a decision, they can use a voting rule to aggregate their preferences. But which rule to use is a difficult question. Different rules have different properties, and social choice theorists have found arguments for and against most of them. These arguments are aimed at the expert reader, used to mathematical formalism. We propose a logic-based language to instantiate such arguments in concrete terms in order to help people understand the strengths and weaknesses of different voting rules. Our approach allows us to automatically derive a justification for a given election outcome or to support a group in arguing over which voting rule to use. We exemplify our approach with an in-depth study of the Borda rule.