Here's the bias! A (Re-)Reassessment of the Chilean electoral system

Abstract

Most scholars of the (now abandoned) Chilean legislative electoral system, known as the “binomial system”, have noted the many ways it was designed to benefit the ideological right. However, Zucco (2007) challenges this conventional wisdom by arguing that there is no bias through the electoral system's majoritarian character, no bias through malapportionment, and that designers could have designed a system to better benefit the ideological right. This paper uses comuna level electoral returns and simulations from Chile's 1988 plebiscite to show that the system was indeed designed to 1) reduce the number of parties in the Chilean party system and 2) minimize electoral losses and maximize electoral gains of the political right. It further argues that, 3) it would have been difficult to design a legislative electoral system to better over-represent the ideological right given the constraints and political context of the time. The analysis strongly supports the rationality of electoral engineering to benefit designers and their allies, even under sub-optimal conditions of limited time and resources. Though the system was abandoned in 2015 in favor of a moderate proportional representation system, it is important to set the record straight in terms of electoral engineers' intents and purposes.