Frances Woolley sets out to consider the efficiencies of vote-swapping and ends up considering the nature of our democracy.
The question is the wrong one to ask. If Party A wins three seats, then it can pursue policies that benefit people who do (or potentially might) vote for party A. If parties A, B and C win one seat each, they will pursue policies that benefit a different set of electors, not just those who vote for party A. But will a coalition government pursue policies that benefit a broader section of the electorate?
It’s not obvious. It all depends what happens at the coalition stage, when different parties are attempting to form governments. An interesting working paper by Amedeo Piolatto argues that, in certain circumstances, the power wielded by small parties in the coalition formation process can cause proportional representation systems to lead to political outcomes that are less representative of the interests of the broader population than first past the post type systems.