Pairwise consensus and Borda rule

Abstract

We say that a preference profile exhibits pairwise consensus around some fixed preference relation, if whenever a preference relation is closer to it than another one, the distance of the profile to the former is not greater than its distance to the latter. We say that a social choice rule satisfies the pairwise consensus property if it selects the top ranked alternative in the preference relation around which there is such a consensus. We show that the Borda rule is the unique scoring rule that satisfies this property.