With the election results in the UK election finishing up, a lot of people have pointed out that the number of seats some of the parties got in parliament is far disproportionate to their vote share. Thus, ukip got around 10% of the vote (or around 4 million votes), but only 1 seat, whereas the SNp got 56 seats with millions fewer. In response to this, various people have called for electoral reform. What reasons are there not to change the system?
I think the positive arguments are really a mix.
- The current UK system guarantees geographical representation. It is more difficult to get this with PR.
- The current UK system has a clearly identifiable person who represents a clearly specified set of people. Those people can fire (not re-elect) their MP if they think they are not doing a good job.
- The current UK system has historically given a majority to one party. This has various advantages over coalition politics. In my view perhaps the most important is that the electorate knows exactly what they are voting for. In coalition politics the policies of the new government are decided after the election.
- Some people simply don't want extreme minority views to be represented at all in parliament. For example, PR would have given MPs to the BNP historically (although not in the 2015 election I believe). The first past the post system ensures that only views that are strongly held by a significant local population are represented in parliament.
We have that same argument in Canada every election. The argument FOR the system is that, from a regional perspective, the representative did indeed win the most local votes to represent their community. To usurp that by any proportional system removes true local representation. the question then becomes whether local representation is more important than overall proportionality. The answer to that depends on how much local representation can truly affect things like local payments from public coffers, and how independant your local voice is within their party. In Canada it has got really bad where the parties almost always vote as blocks - no matter what. In that case, first past the post fails miserably.
In addition to the argument Michael Broughton has put above, that the MP is the clear first choice of his or her local area, another argument for FPTP is that it usually (not always!) gives a decisive result quickly. Under more proportional systems there is often complex haggling between several parties before a government is formed, involving dramatic concessions to smaller parties in order to get their support.
One argument missing from previous answers is the simplicity of the system. How individual votes contribute to the final result is transparent and you only need one round of voting (as opposed to the French system which is still simple and strongly majority-oriented while giving smaller parties a bit more space but requires two rounds of voting – with one or two weeks in-between – for each election). Many alternative systems require complex calculations (e.g. the Irish STV) or lend themselves to strange paradoxes (in Germany, there have been elections in which supporters of a given party in a specific district could have ensured an extra seat for their party of choice by not voting at all).
Note that the almost complete lack of representation for UKIP and other small parties are the clearest evidence for the issues with FPTP. Because the SNP has a local stronghold, it would be very successful in any system. Based on its proportion of the national vote, it could expect at least 30 seats, which is also roughly half the seats for Scotland where it had about 50% of the vote. That's less than the 56 seats it was able to secure in the current system but still quite a lot.
Note that there is a common counter-argument to the simplicity argument, namely that it does not matter whether voters understand how the seats are assigned, as long as the parliament ultimately reflects their preferences.