The informational basis of scoring rules

We consider voting wherein voters assign a certain score to each of the many available alternatives. We study the normative properties of procedures that aggregate the scores collected in the ballot box. A vast class of ballot aggregators, including procedures based on the pairwise comparison of alternatives, satisfy May’s famous conditions in our framework. We prove that, within such a plethora of procedures, scoring rules are singled out by a property related to their informational basis: in order to determine the winner, they do not take into account the specific distribution of scores chosen by each voter. The result is shown to hold regardless of the introduction of asymmetry among the alternatives.