第18章公共経済

Most developed countries today have a democratic system of government: citizens express their opinions through votes and those votes affect the direction of the country. The advantage of democracy over other systems is that it allows everyone in a society an equal say and therefore may reduce the possibility of a small group of wealthy oligarchs oppressing the masses. There is no such thing as a perfect system, and democracy, for all its popularity, is not without its problems, a few of which we will examine here.

We sometimes sum up and oversimplify democracy in two words: “Majority rule.” When voters face three or more choices, however, then voting may not always be a useful way of determining what the majority prefers.

As one example, consider an election in a state where 60% of the population is liberal and 40% is conservative. If there are only two candidates, one from each side, and if liberals and conservatives vote in the same 60–40 proportions in which they are represented in the population, then the liberal will win. What if the election ends up including two liberal candidates and one conservative? It is possible that the liberal vote will split and victory will go to the minority party. In this case, the outcome does not reflect the majority’s preference.

Does the majority view prevail in the case of sugar quotas? Clearly there are more sugar consumers in the United States than sugar producers, but the U.S. domestic sugar lobby (www.sugarcane.org) has successfully argued for protection against imports since 1789. By law, therefore, U.S. cookie and candy makers must use 85% domestic sugar in their products. Meanwhile quotas on imported sugar restrict supply and keep the domestic sugar price up—raising prices for companies that use sugar in producing their goods and for consumers. The European Union allows sugar imports, and prices there are 40% lower than U.S. sugar prices. Sugar-producing countries in the Caribbean repeatedly protest the U.S. quotas at the World Trade Organization meetings, but each bite of cookie, at present, costs you more than if there were no sugar lobby. This case goes against the theory of the “median” voter in a democracy. The median voter theory argues that politicians will try to match policies to what pleases the median voter preferences. If we think of political positions along a spectrum from left to right, the median voter is in the middle of the spectrum. This theory argues that actual policy will reflect “middle of the road.” In the case of sugar lobby politics, the minority, not the median, dominates policy.

Sometimes it is not even clear how to define the majority opinion. Step aside from politics for a moment and think about a choice facing three families (the Ortegas, the Schmidts, and the Alexanders) who are planning to celebrate New Year’s Day together. They agree to vote on the menu, choosing from three entrees, and they agree that the majority vote wins. With three families, it seems reasonable that one producing choice will get a 2–1 majority. What if, however, their vote ends up looking like Table 18.1?

Clearly, the three families disagree on their first choice. However, the problem goes even deeper. Instead of looking at all three choices at once, compare them two at a time. (See Figure 18.2) In a vote of turkey versus beef, turkey wins by 2–1. In a vote of beef versus lasagna, beef wins 2–1. If turkey beats beef, and beef beats lasagna, then it might seem only logical that turkey must also beat lasagna. However, with the preferences, lasagna is preferred to turkey by a 2–1 vote, as well. If lasagna is preferred to turkey, and turkey beats beef, then surely it must be that lasagna also beats beef? Actually, no. Beef beats lasagna. In other words, the majority view may not win. Clearly, as any car salesperson will tell you, the way one presents choices to us influences our decisions.

We call the situation in which Choice A is preferred by a majority over Choice B, Choice B is preferred by a majority over Choice C, and Choice C is preferred by a majority over Choice A a voting cycle. It is easy to imagine sets of government choices—say, perhaps the choice between increased defense spending, increased government spending on health care, and a tax cut—in which a voting cycle could occur. The result will be determined by the order in which interested parties present and vote on choices, not by majority rule, because every choice is both preferred to some alternative and also not preferred to another alternative.