When promoting certain electoral systems over others, proponents tend to make claims that one system may be "fairer", "more democratic, "representative" or "effective" than others. In this article, the author suggests the fundamental problem in evaluating electoral systems in terms of these criteria is not necessarily that there exists an unyielding trade-off between representation and accountability. Rather, it is that there is no strong normative basis that allows us to distinguish representative from unrepresentative electoral outcomes, either because these outcomes are products of a voting cycle or because our measures of representation are ambiguous.

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Ideally, government is representative and accountable; representative in the sense that its policies align with citizens' interests, and accountable in the sense that it is answerable to citizens for its conduct and responsive to their demands. The electoral system plays an important role in determining how representative and accountable a government is in practice. Yet, it is tremendously difficult to identify an optimal electoral system, that is, one that maximizes both representation and accountability. This is because much research shows that electoral systems that advance representation tend to do so at the expense of accountability, and vice versa. (1)

The trade-off between accountability and representation is often portrayed as a fundamental obstacle to identifying an optimal electoral system, but any such trade-off is not really what prevents us from identifying an optimal electoral system. It is rather that we can neither i) reliably identify more or less representative electoral outcomes, nor ii) rely on repeated elections to hold incumbents to account.

The Representation-Accountability Trade-off

Representation

One can appreciate the effect of the electoral system on representation by recalling Downs's model of electoral competition. (2) The two parties in Downs's model appeal to voters by altering their policy positions. The well-known result of the model is that both parties converge on the position of the median voter, who then randomly supports one of the parties to give it a majority. If we take as a metric of representation the policy distance between the median voter and the median legislator (this is called congruence), the result is perfectly representative.

Few real-world elections feature exactly two parties. Once more than two parties inhabit Downs's model one or more of the parties may benefit by diverging from the median voter. This has less to do with the electoral formula (plurality or proportional representation (PR)) than the district magnitude. (3) Even so, Figures la and lb convey how parties tend to arrange themselves under plurality or PR, respectively. (4) In Figure la, C takes up a position to the right of the median voter in the hope that A and B will split the vote to the left of the median voter so that C can secure a plurality of votes on the right. In Figure lb, A, B and C distribute themselves evenly about the median voter's position.

The representational consequences of these two stylized elections are quite different. If C were to win the plurality election in Figure la, there would be a substantial gap between the median voter and the majority party. There is no outright winner in PR elections, and in theory A, B, and C ought to arrange themselves in Figure lb such that each obtains an equal share of the vote (or else each would have cause to adopt a somewhat different position)....