Ranked-choice voting versus first-past-the-post: how polarization shapes their performance

What the paper says

This paper examines the relative performance of ranked-choice voting (RCV) and first-past-the-post (FPP) in selecting the Condorcet winner, depending on the level of polarization in society. Using a stylized model with three candidates and single-peaked voter preferences, we uncover a novel non-monotonic relationship between RCV’s advantage over FPP and the level of support for the Condorcet winner, measured as the proportion of voters who rank the Condorcet winner first. When this support is either very high or very low, both voting methods perform similarly—either both succeed or both fail to select the Condorcet winner. By contrast, at intermediate levels of support, RCV succeeds in selecting the Condorcet winner while FPP does not. In this sense, RCV performs best when polarization is moderate. Moreover, even in highly polarized electorates where neither method selects the Condorcet winner, RCV retains an important advantage by avoiding the selection of the Condorcet loser. These findings are particularly relevant given that RCV is often proposed as a way to mitigate polarization and promote more moderate electoral outcomes, highlighting the importance of considering a society’s ideological composition when evaluating electoral reforms.