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Median Voter Theory

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Median Voter Theory

The median voter theorem states "a majority rule voting system will select the outcome most preferred by the median voter".[1]

As with every economic model, the median voter theorem makes several assumptions. First, the theorem assumes voters can place all election alternatives along a one-dimensional political spectrum.[2] It seems plausible that voters can do this if they are voting for a single policy or if they can clearly place political candidates on a left-to-right continuum. However, problems arise if there are multiple policies being considered on the referendum, thus making the continuum multidimensional. Second, the theorem assumes that voter’s preferences are single-peaked, which means that voters choose alternatives closest to their most preferred outcome. This assumption predicts that the further away the outcome is from the voter’s most preferred outcome, the less likely the voter is to select that alternative.[3] Third, the median voter theorem assumes that voters always vote for their true preferences. It is clear from the research that voters do not always do this.[4] Finally, the median voter theorem applies best to majoritarian election system.

Explanations

To appreciate the logic of the median voter model, consider a setting where three individuals: Al, Bob, and Charlie are to choose a restaurant to eat lunch at. Al prefers a restaurant where lunch can be paid for $5, Bob favors a bit better fare at a restaurant serving $10 lunches, and Charlie wants a gourmet restaurant where lunch will cost around $20. Bob can be said to be the median voter, because there are exactly the same number of individuals who prefer a more expensive restaurant than Bob as there are who prefer a less expensive restaurant than Bob, here one each. For convenience assume that, given any two options, each member of the lunch group prefers restaurants with prices closer to their preferred restaurant to ones that are farther from it. Now consider some majority decisions over alternative restaurants:

Options Pattern of votes Result
$20 vs. $5 A: 5 B: 5 C: 20 5
$10 vs. $20 A: 10 B: 10 C: 20 10
$10 vs. $5 A: 5 B: 10 C: 10 10

The weak form of the median voter theorem says the median voter always casts his or her vote for the policy that is adopted. Note that Bob always votes in favor of the outcome that wins the election. Note also Bob's preferred $10 restaurant will defeat any other. If there is a median voter, his (or her) preferred policy will beat any other alternative in a pairwise vote. (The median voter's ideal point is always a Condorcet winner.) Consequently, once the median voter's preferred outcome is reached, it cannot be defeated by another in a pairwise majoritarian election. The strong form of the median voter theorem says the median voter always gets his most preferred policy.[5]

The median voter theorem seems to explain a few of the phenomena that occur in majoritarian voting systems. First, it may explain why politicians tend to adopt similar platforms and campaign rhetoric. In order to win the majority vote, politicians must tailor their platforms to the median voter.[2] For example, in the United States, the Democratic and Republican candidates typically move their campaign platforms towards the middle during general election campaigns. Just as sellers in the private market try to win over their competitor’s customers by making slight changes to better their products, so, too, do politicians deviate only slightly from their opponent’s platform so as to gain votes.[2]

Second, the median voter theorem may explain why radical candidates or parties rarely get elected. If a politician or party is, for example, an extreme liberal on the very left end of the political spectrum, they will not capture nearly as many votes as the politician whose campaign platforms are more moderate. Finally, the theorem may explain why two major political parties tend to emerge in majoritarian voting systems (Duverger's law). Indeed, in the United States there are countless political parties, but only two major parties play a part in almost every major election: the Democratic and Republican parties. According to the median voter theorem third parties will rarely, if ever, win elections for the same reason why extreme candidates do not tend to win. The major parties tend to co-opt the platforms of the minor parties in order to secure more votes.[1]

History

In his 1929 paper titled “Stability in Competition”, Harold Hotelling notes in passing that political candidates’ platforms seem to converge during majoritarian elections.[2] Hotelling compared political elections to businesses in the private sector. He postulated that just as there is not a striking difference between salesmen's products, so, too, there is not a stark contrast between electoral platforms. This is because politicians, just like salesmen with consumers, seek to capture the majority of voters. Duncan Black, in his 1948 paper titled “On the Rationale of Group Decision-making” provided a form analysis of majority voting that made the theorem and its assumptions explicit.[6] Black wrote that he saw a large gap in economic theory concerning how voting determines the outcome of decisions, including political decisions. Black’s paper thus triggered the research on how economics can explain voting systems. In 1957 with his paper titled “An Economic Theory of Political Action in Democracy”, Anthony Downs expounded upon the median voter theorem.[7]

Accuracy

Several important economic studies strongly support the median voter theorem. For example, Holcombe analyzes the Bowen equilibrium level of education expenditures for 257 Michigan school districts and finds that the actual expenditures are only about 3% away from the estimated district average.[8]

The theorem also explains the rise in government redistribution programs over the past few decades. Thomas Husted and Lawrence W. Kenny examined growth of redistribution programs especially between the years of 1950 and 1988.[9] Tom Rice also writes that voters with the median income will take advantage of their majority status by electing politicians that will tax those who are earning more than the median voter, and then redistribute this to those who are below the median.[10] More specifically, Rice demonstrates that if a systematic closing of the gap between people of the median and mean income levels in the United States could be shown, more credibility can be given to the median voter theorem. Up until the mid-1960s, Rice says the gap between median and mean income levels tightened. Three main forces served to tighten this gap. First, the strength of the Democratic Party in the United States Congress in the decades leading up to the 1960s, as Democrats are more disposed to redistribution. Second, increased turnout to the polls, just as Husted and Kenny postulated, tightened the gap because an increase in voters means more individuals of lower income are voting. Finally, since unemployment, which causes median income families to fall below the median income, compared to after the 1960s, was relatively low, this tightened the gap.

Limitations

The median voter theorem has several limitations. Keith Krehbiel postulates that there are many factors which prevent the political process from reaching efficiency.[11] Just like transaction costs prevent efficiency in market exchanges, things in the majoritarian voting process inhibit it from reaching optimality. With the median voter theorem in particular, Krehbiel argues that voters' inability to directly amend legislation inhibits the theorem from holding true. Sometimes, as Krehbiel writes, the policies being voted on are too complex to be placed within a one-dimensional continuum. Buchanan and Tollison also note that this is a problem for median voter theorem, which assumes that decisions can be made on a one-dimensional field.[12] If voters are considering more than one issue simultaneously, the median voter theorem is inapplicable. This may happen if, for example, voters may vote on a referendum regarding education spending and police spending simultaneously.

A larger problem for the median voter theorem, however, is the problem of the incentives structure for government representatives. Downs, in “A Theory of Bureaucracy”, writes that people's decisions are motivated by self-interest, an idea deeply rooted in the writings of Adam Smith.[13] This holds for the government system as well, because it is composed of individuals who are self-interested. One cannot guarantee the degree to which a government representative will be committed to the public good, but it is certain that, to some degree, they will be committed to their own set of goals. These goals can include a desire to serve the public interest, but most often they include the desire for power, income, and prestige. To continue obtaining these things, then, officials must secure reelection. When representatives are constantly focused on becoming reelected, this distorts the orders they receive from their constituents; representatives will interpret what their constituents want into benefits for themselves.[13] They will tend to vote for short-run policies that will aid in getting them reelected.[1]

References

  • Buchanan, James M. and Robert D. Tollison (1984). The Theory of Public Choice—II, Ann Arbor: University of Michigan Press.
  • Clinton, Joshua D. (2006). “Representation in Congress: Constituents and the Roll Calls in the 106th House”, The Journal of Politics, 68(2): 397-409.
  • Congleton, Roger (2002). The Median Voter Model. In *
  • Downs, Anthony (1957). “An Economic Theory of Political Action in a Democracy”, Journal of Political Economy, 65(2): 135-150.
  • Holcombe, Randall G. (1980). “An Empirical Test of the Median Voter Model”, Economic Inquiry, 18(2): 260-275.
  • Holcombe, Randall G. and Russell S. Sobel (1995). “Publicness of State Legislative Activities”, Public Choice, 83: 47-58.
  • Husted, Thomas A. and Lawrence W. Kenny (1997). “The Effect of the Expansion of the Voting Franchise on the Size of Government”, Journal of Political Economy, 105(1): 54-82.
  • Krehbiel, Keith (2004). “Legislative Organization”, The Journal of Economic Perspectives, 18(1):113-128.
  • McKelvey, Richard D. (1976). “Intransitives in Multidimensional Voting Models and Some Implications for Agenda Control”, Journal of Economic Theory, 12: 472-482.
  • Rice, Tom W. (1985). “An Examination of the Median Voter Hypothesis”, The Western Political Quarterly, 38(2): 211-223.
  • Romer, Thomas and Howard Rosenthal (1979). “The Elusive Median Voter”, Journal of Public Economics, 12(143-170).
  • Sobel, Russell S. and Randall G. Holcombe (2001). “Unanimious Voting Rule”, Public Choice, 106: 233-242.

External links

  • The Median Voter Model
  • to tariffs
  • to local private goods
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