AN ECONOMIC THEORY OF DEMOCRACY
Anthony Downs
Addison Wesley Longman, Inc., paperback (1997)
(Originally published by Harper and Row, 1957)

Winner of the 1989 Leon D. Epstein Outstanding Book Award honoring a book of outstanding and lasting significance in the field given by the APSA Organization Section on Political Organizations and Parties. Received the 1999 Philip E. Converse Book Award given by the APSA Organized Section on Elections, Public Opinion, and Voting Behavior for an outstanding book in the field published at least five years before.

...In chapter eight of the book, Downs explains how the concept of ideology is central to his theory. Depending on the ideological distribution of voters in a given political community, electoral outcomes can be stable and peaceful or wildly varied and even result in violent revolution. The likely number of political parties can also be identified if one also considers the electoral structure. If the ideological positions of voters are displayed in the form of a graph and if that graph shows a single peak, then a median voter can be identified and in a representative democracy, the choice of candidates and the choice of policies will gravitate toward the positions of the median voter. However, if the graph of ideological distribution is double-peaked, indicating that most voters are either extremely liberal or extremely conservative, the tendency toward political consensus or political equilibrium is difficult to attain because legislators representing each mode are penalized by voters for attempting to achieve consensus with the other side by supporting policies representative of a middle position. Here is a list of the key propositions Downs attempts to prove in chapter eight:

1. A two-party democracy cannot provide stable and effective government unless there is a large measure of ideological consensus among its citizens.
2. Parties in a two-party system deliberately change their platforms so that they resemble one another; whereas parties in a multi-party system try to remain as ideologically distinct from each other as possible.
3. If the distribution of ideologies in a society’s citizenry remains constant, its political system will move toward a position of equilibrium in which the number of parties and their ideological positions are stable over time.
4. New parties can be most successfully launched immediately after some significant change in the distribution of ideological views among eligible voters.
5. In a two-party system, it is rational for each party to encourage voters to be irrational by making its platform vague and ambiguous. (Wikipedia.com)

BOOK DESCRIPTION
PUBLISHER
This book seeks to elucidate its subject-the governing of democratic state-by making intelligible the party politics of democracies. Downs treats this differently than do other students of politics. His explanations are systematically related to, and deducible from, precisely stated assumptions about the motivations that attend the decisions of voters and parties and the environment in which they act. He is consciously concerned with the economy in explanation, that is, with attempting to account for phenomena in terms of a very limited number of facts and postulates. He is concerned also with the central features of party politics in any democratic state, not with that in the United States or any other single country.

"...One of the chief underpinnings of public choice theory is the lack of incentives for voters to monitor government effectively. Anthony Downs, in one of the earliest public choice books, An Economic Theory of Democracy, pointed out that the voter is largely ignorant of political issues and that this ignorance is rational. Even though the result of an election may be very important, an individual's vote rarely decides an election. Thus, the direct impact of casting a well-informed vote is almost nil; the voter has virtually no chance to determine the outcome of the election. So spending time following the issues is not personally worthwhile for the voter...." (from the article "Public Choice Theory," by Jane S. Shaw, in The Concise Encyclopedia of Economics on The Library of Economics and Liberty website)

(from reader on Amazon.com)
"...an easy to read introdution to the basics of voting theory. It is accessible to the casual reader as well as the hardcore acedemic. It's take on the electoral competition have become staples of high school civics as well as academic political theory.

Down's most famous innovation is the result that two party competition leads to both parties offering the same platform in order to maximize votes.

This formulation is actually the Hotelling spatial competition model applied to elections....Moreover it forms the basis for the median voter theorem."