A Consistent Extension of Condorcet’s Election Principle

Abstract

Condorcet’s principle of choosing the majority alternative whenever one exists is violated not only by Borda’s rule but by any scoring method; nevertheless the essential property of scoring functions—“consistency” of the outcome under aggregation of subgroups—is shown to be compatible with Condorcet’s principle. Moreover these two properties, suitably interpreted, together with neutrality, determine a unique rule known as Kemeny’s rule.