How PR leads to more centre-left govts and more equal societies.

To a very considerable extent, redistribution is the result of electoral systems and the class coalitions they engender...

Electoral systems matter because they alter the bargaining power and coalition behaviour of groups with different interests.

In majoritarian systems, parties have to balance the incentive to capture the median voter with the incentive to pursue the policy preferred by their core constituencies. Because the median voter tends to be closer to the distributive interests of the centre-right party, any probability that parties will defect from their electoral platform once elected will tend to make the median voter more likely to vote for the centre right.

This result contrasts to multi-party PR systems where middle class parties have to compromise with left or right parties to govern. In this context centre parties will find it in their own interests to ally with the left. This result follows when in addition to flat rate benefits, there are means tested tranfers, because the middle class can then use the latter to bargain a tax rate closer to their preference while placing the burden of redistribution on the rich.

For the full paper click here.