Key’s ‘Labour Lite’ and Why Parties Move to the Middle

September 9, 2009

Remember back to before NZ’s November General Election and the scrutiny of National’s leader and future Prime Minister John Key? He was labeled as ‘Labour-lite’ and centrist; his party was careful not to wage war on some of Helen Clark’s more popular policies; the differences between the two main parties were small, negligible even.

And for those who follow US politics – you must have been struck by the partisan divide in both society and politics between the Democrats and Republicans. It is, in the words of a columnist, ‘The 50/50 Nation‘. Heck, the two camps even have their own separate news channels!

Over in Germany, people ask themselves: What is the SPD doing in opposition? (oops, sorry, the election isn’t for 2 weeks. I meant, Grand Coalition.) They could form a government with the Greens and the Left Party tomorrow!

Discussion of all these issues, and some others which I have speculated upon here previously, can be informed by a powerful, but simple, political science model (originating in economics) called the Median Voter Theorem.

Briefly, the theorem is a model of majority decision making which states that the median voter’s preferred policy will beat any alternative in a vote; in a stronger form it also says that the median voter will almost always get his/her most preferred policy. The rationale behind it is too much for this blog and is explained briefly and clearly here, but the consequences are far-reaching.

Median_voter_modelIf we apply the model to the Left-Right spectrum above, we can come to the following conclusions:

1) if voters cast their vote for the candidate closest to their ideal policy, then the candidate who stands nearest to the median voter will win. In this case, this would be candidate A, who is closest to point M.

2) if the candidates are free to choose their policies, they will choose positions which will place them closest to the median voter’s at M; so candidates A and B will move in the directions of the arrows towards the middle of the graph and the median voter’s preferences will be fulfilled.

The theory puts the median voter in the lucky position of always getting what they want, but it also has other consequences – many more than will be expanded on here, but to go back to the examples above:

Key vs. Clark in NZ: parties will choose policies which are moderate and middle of the road; no wonder that they look so similar.

Democrats vs. Republicans in the US: if parties continue to act as above for many years they could create blocs, each accounting for approximately half of the population (see the column from Mickey Kraus).

The SPD and the Left Party in Germany: parties will be very careful not to take extreme positions which could alienate voters closer to the median.

So there you have it. A brief but hopefully not-too-incomplete rundown of the Median Voter Theorem in five minutes. A simple, powerful analytical tool for analyzing party politics.

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3 Responses to “Key’s ‘Labour Lite’ and Why Parties Move to the Middle”

  1. Red Rosa Says:

    The theory may be OK as a political snapshot, and for the week to week battles, but from a longer perspective it does not explain the steady shift in policies over decades.

    In the UK, the Attlee Labour government of 1945, with its members addressing each other as ‘comrade’, its nationalization of coal, steel and transport, now looks almost Stalinist. Though in a gentlemanly, Edwardian English manner!

    UK policies drifted back to the centre in the UK, right through to the late 70s, but the Thatcher seismic shift to the Right has gone largely uncorrected.

    Many in the UK Conservative Party, surveying the 1945 landslide, would have predicted a Socialist future with large parts of the economy in State control for ever onwards. How wrong they were!

    Of course, governments are not necessarily elected on policy, and in power their policies may differ from their election ‘promises’.

    But no-one in NZ 12 months ago would have predicted the return of knighthoods, or the string of rightwing flicks of the whip, which have marked the Key government so far.

    it would be fair to say that the ‘median NZ voter’ has had his share of surprises!

    • comparablog Says:

      Of course the theorem cannot explain shifts in public opinion; it simply explains how parties react to them: by moving to the middle of the political spectrum in order to secure a majority.

      That the public cannot vote on everyday policies is a feature of representative democracy and so it is fair to say that parties may deviate from the median during their term in government.

      However they will always be careful not to deviate too far, as they can be punished at the next election.

      One has to be careful in confusing changes in party policy with changes in public opinion.


  2. […] to the inate tendency of party policy to tend to the middle, it can be safely assumed that the majority of the votes cast will be gathered by two large parties […]


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