Policy competition, spatial distance and electoral instability

This article assesses the extent to which spatial distance accounts for variations in levels of aggregate electoral mobility, following the hypothesis that more extended distances result in less mobility. Distances are derived from an analysis of the economic policy content of election programmes in eleven West European democracies between 1945 and 1985. Two indices are devised, one measuring the distance between the most extreme parties, and the other measuring the distance between the class‐left block of parties and all other parties. The first index proves inadequate as a test of the hypothesis, being largely dependent upon the number of parties in competition. The second index offers quite strong support for the hypothesis and shows that voters are more likely to be volatile in situations in which policy distances are relatively abbreviated. The comparison between the two indices yields a number of important substantive and methodological implications for the empirical analysis of the political space of competition.