Political Demands, Political Opportunities: Explaining the Differential Success of Left-Libertarian Parties

Abstract

Using qualitative comparative analysis, we examine why left-libertarian parties, associated with environmental and other "new social movements," have been relatively successful in some western democracies but not others. We conceptualize the parties as products of new citizen demands on the one hand, and of political opportunity structures, which govern party supply, on the other. We show that supply-side factors, such as a strong left and the existence of proportional representation, tend to work together to facilitate party innovation. A strong left appears more likely to downplay left-libertarian issues and push new-left activists to form separate parties, while proportional representation eases entry into the party system. Demand-side factors play a significant but lesser role. The theoretical and methodological strategies employed here have the potential to help political sociologists explain the variable success of other types of party innovators.