Does Fragmentation Matter? Party System Fractionalisation and Executive-Legislative Relations in Parliamentary and Presidential Systems

Modern democracy is characterised by the increasing fragmentation of party systems. Since the Third Wave of democratisation in the early 1970s, traditional political parties have lost ground to new challengers, and as a result the average number of political parties is on the rise across modern democracies. However, while the global trend towards greater fragmentation is clear, there is considerable unexplained variance in the effects of party fragmentation across parliamentary and presidential systems. This paper seeks to explore the varied effects of party political fragmentation by focusing specifically on the partisan and legislative powers of the heads of state/government in presidential and parliamentary systems. This analysis draws on an original collection of both global and small-N data.