On May 5th Britons will go to the polls to decide whether or not they wish to change the system by which they appoint legislators to the House of Commons. The current system, First Past the Post (FPtP), is disparaged as "broken" by policy makers from across the political spectrum but its mooted replacement, the Alternative Vote (AV) system, has its own flaws which is why the current Conservative government is campaigning for a no vote, putting them at logger-heads with their Liberal Democrat coalition partners.
So what's wrong with the current system? On paper it sounds fair, the country is divided into districts of similar population, every citizen gets one vote and the candidate who receives the most endorsements goes on to represent her district in the national legislator. But this system has a number of flaws and over time political scientists have come up with some pretty interesting solutions to address them.
The first problem with FPtP is that it's entirely possible for a candidate that represents a minority of the voters in her district to be elected. Imagine 4 political parties field candidates in a particular district. The Green, Yellow and Blue parties each receive 24% of the votes and the Red party gets 28%. The Red party wins the seat and a person with the support of less then 30 in every 100 people in her district goes on to represent said district in parliament. Two systems have been proposed to help eliminate this problem. The first is two-round voting. Under this system a preliminary election is held after which all but the two most popular candidates are eliminated. The two remaining candidates then face each other in a run-off. With only 2 choices possible the winner will, by definition, have majority support. Elections can be costly though which is where the AV system comes in. It guarantees majority support and voters only have to go to the polls once. Voters rank the candidates in order of preference. If no candidate receives an objective majority of the votes cast the least popular candidate is eliminated from the race and their votes are redistributed to the candidates that their voters had indicated as their second preference. This process of elimination and redistribution continues until someone passes the 50% threshold.
Both these systems solve the problem of minorities controlling legislation on the local level but there is a further problem that plagues both systems and it becomes apparent when you look at things on the national level. Imagine 2 districts; District 9 and District 13. Both have a voting-age population of 700. In District 9 the Blue party tallies 400 votes and the Yellow party receives 300. In District 13 the Red party gets 400 votes and the Yellow party again polls 300. In the national legislator these districts will be represented by one Red and one Blue candidate even though the Yellow party has more support in the region then either of them. The system suggested as a cure for this is Proportional Representation (PR) in which a party that received, for example, 15% of the votes nationwide would receive 15% of the seats in the legislator subject to a minimum threshold.
So if PR is known to solve the problems inherent in both the FPtP and AV voting systems why isn't it widely implemented? Their are two very bad outcomes that can result from a pure PR system. First, small parties can multiply leading to rainbow coalitions without a clear leadership structure incapable of taking immediate action in times of crisis. Second, minorities with diffuse geographical support are not always the kind of minorities that deserve representation. Indeed deserving minorities such as those based on religion, culture or ethnicity tend to be geographically clustered and are thus no better served by PR then by AV or FPtP. Minorities with diffuse geographical support tend to represent the fringe of political ideology, the far-left and the far-right. In the above example switching to a pure PR system would hand the Yellow party a clear a majority. If the Yellow party is of an extremist bent that country may never see another election.
In light of the fact that each of the voting systems has its flaws contemporary commentators favour a mixed system with a certain fraction of the seats in the legislator being decided on a traditional FPtP or AV basis and the remainder awarded to parties on the basis of their nationwide performance (i.e. on a PR basis). To see how this would improve matters imagine the election results in districts 9 and 13 above were repeated in a further 48 districts. Under pure FPtP this would result in a government composed entirely of Reds and Blues, quite unfair for all those Yellow voters. But say we added 40 seats on a PR basis as they do in Scotland. 16 would go to the Yellow party, 12 to the Reds and 12 to the Blues. The Yellows would now find themselves capable of taking part in a coalition government, giving them the recognition they deserve, while the Red or Blue party would have a clear political mandate to govern, controlling 37 seats in a 53 seat coalition.
