Is Proportional Representation More Favourable to the Left? Electoral Rules and Their Impact on Elections, Parliaments and the Formation of Cabinets

How do electoral rules affect the composition of governments? It is a robust finding that countries with majoritarian rules more often elect conservative governments than those with proportional representation (PR) electoral systems. There are three explanations for this pattern. The first stresses the impact of voting behaviour: the middle class more often votes for right-wing parties in majoritarian electoral systems, anticipating governments’ redistributive consequences. The second explanation is based on electoral geography: the regional distribution of votes may bias the vote-seat translation against the Left in majoritarian systems due to the wide margins by which the Left wins core urban districts. The third explanation refers to party fragmentation: if the Right is more fragmented than the Left in countries with PR, then there is less chance of a right-wing party gaining formateur status. This study tests these three hypotheses for established democracies over the entire post-war period. It finds the first two mechanisms at work in the democratic chain of delegation from voting via the vote-seat translation to the formation of cabinets, while party fragmentation does not seem to co-vary as much as expected with electoral rules. These findings confirm that majoritarian systems have a substantive conservative bias, whereas countries with PR show more differentiated patterns.