Anthony Downs

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. Conversely, 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...