[1] The book set forth a model with precise conditions under which economic theory could be applied to non-market political decision-making.
Downs' theory abstains from making normative statements about public policy choices and instead focuses on what is rational, given the relevant incentives, for government to do.
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.
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.
In anticipation of such criticism, Downs quotes Milton Friedman in chapter two that: “Theoretical models should be tested primarily by the accuracy of their predictions rather than by the reality of their assumptions”.