Spatial Models of Party Competition

The use of spatial ideas to interpret party competition is a universal phenomenon of modern politics. Such ideas are the common coin of political journalists and have extraordinary influence in the thought of political activists. Especially widespread is the conception of a liberal-conservative dimension on which parties maneuver for the support of a public that is itself distributed from left to right. This conception goes back at least to French revolutionary times and has recently gained new interest for an academic audience through its ingenious formalization by Downs and others. However, most spatial interpretations of party competition have a very poor fit with the evidence about how large-scale electorates and political leaders actually respond to politics. Indeed, the findings on this point are clear enough so that spatial ideas about party competition ought to be modified by empirical observation. I will review here evidence that the “space†in which American parties contend for electoral support is very unlike a single ideological dimension, and I will offer some suggestions toward revision of the prevailing spatial model.