Revenge of Maurice Duverger

In the 1950s, Maurice Duverger demonstrated and had his name applied to a fact of plurality electoral systems with single-member constituencies (like the USA and UK) that they strongly favor the establishment of a 2-party system. We know from many other experiences in life that in any selection with only one winner, there is very quickly a front runner and a single best runner-up challenger. Then everyone else more or less has to pick sides. For curious reasons, the UK is not quite a two-party system. The Liberals and Tories were the two main parties in the late 19th century into the 1920s, when Labour managed to oust the Liberals and create a new duopoly. The Liberal Dems never went away, however. Now they are possibly in a position to create a hung parliament.

How to explain this? Why isn't the UK electorate swinging decisively to the Tories and the anti-Tories, with just one party taking up the slack? How do parties like BNP and UKIP ever get elected over the Tories in those right-leaning districts? I wonder if the answer is the lack of independence of MPs. In the USA, each representative can attune himself or herself to the interests of the district, as can each challenger. In the UK, they can't - they are all tied to a single national platform. Imagine if, in the USA, all Republicans had to adopt the policy stands of the Georgia GOP: opposed to gay marriage, civil unions, gays in the military, in favor of school prayer, ban all abortions. Well, that party woudl be shut out of much of the country where more liberal Republicans can win today. Imagine that the Dems were all required to favor gay marriage and demand gun control. They too woudl be shut out of large areas. there would be a place for 3d and 4th parties to rise. Indeed, the lack of cohesion ruling parties in the USA - whether the fractious Dems of today or the fractious GOP of 2002 - is an indication of the issues that create space for third parties in the UK electorate.

What is rare in the UK is that any single district has three competitive parties. While it happens, reports indicate a lot of local duopolies. that's what we would expect.

Why do US parties cohere better than UK parties into duopolies? Another feature is the presidency which has long been the organizing force behind national parties even in the 19th century when the Senate was unelected and in non-party caucuses. The presidency is such a winner-take-all prize that it helps organize national coalitions. In the UK, this does not happen because the legislature chooses the executive.

So I ask you, how might we test this? Imagine if, in the USA, it were much harder for representatives to adjust themselves in one of the two legislative houses. It is. Witness the Senate versus the House. The Senate cannot be gerrymandered and Senators are more likely to address national audiences. This may help explain why we see "independents" as a regular feature of the Senate, but not in the House. Also in New York we see four parties - D, R, Conservative, Liberal - which create local duopolies but are permitted to co-endorse candidates and therefore run statewide tickets. If we ever want a third party in the USA, then, we may have to create rules that allow multi-party endorsements of candidates, something that was once the case in many US states.