Ideological Diversity and Government Survival in Western European Parliamentary Democracies

A major lacuna in the empirical investigation of government stability in Western European parliamentary regimes is the failure to test rigorously the hypothesis that the ideological diversity within governments influences their survival in office. This study attempts to remedy this deficiency by developing and testing measures of the concept based on a wide variety of sources, including expert scales of party positions, voter-based estimates of party ideologies, and assessments of party positions derived with the aid of the European Manifestos Project's coding of electoral platforms. The key findings are that not only is ideological diversity inversely related to government survival, even when other relevant factors are taken into account, but that this connection seriously challenges bargaining environment interpretations of stability advanced within the past 2 years.