New Perspectives on May’s Theorem and the Median Voter Theorem

Abstract

The paper defines and analyzes May’s Theorem and the Median Voter Theorem from the Public Policy and Public Choice literature and seeks to compare and contrast the use of both. Through the use of theoretical and applied examples, the paper demonstrates how collective decision-making research has evolved to better inform public policy. Building on Black’s (1948) notion that it is the voter in the ideological middle that decides elections, Holcombe (1980) provides an empirical analysis of this theory, Scervini (2012) attempts to show that the middle class (median) voter decides taxation and redistribution policy, Rowley (1984) takes a New Institutional approach to analyzing voters’ preferences, Groot and van der Linde (2016) conducts a cross-country analysis to see if the Median Voter Theorem holds true across time and cultures, Carrillo and Castanheira (2008) show that voters change their behavior from the preference of the median voter as the press reveals new information about the quality of candidates which alters voters’ perceptions, and Congleton (2003) asserts there may not always be a median voter with examples. Building on May’s Theorem that voting is an aggregation of voters’ preferences, Hotelling (1929), Black (1948), Maskin (1999), Duggan (2015), and Brady and Chambers (2017) expand on social preference theory showing that Arrow (1951) and May (1952)’s work needed to be updated to include verifiable, empirical tests and further refinements. The paper shows how public policy analysis and group decision making theory and application have evolved over the past 75 years and shines some light on areas for future research and analysis. These findings are important because it will help make candidates and policy proposals more palatable to voters in the ideological middle (median voter) who, as the studies show, often determines the winner. The paper will be of interest to anyone involved in public policy and group decision making processes.