Even more AV

More AV comment, from a colleague:

I voted “no”. Why?

1. Arrow’s theorem. Getting democracy “right” is mathematically impossible.
2. Elections are not there to select the “right” government, but to confer legitimacy on that which is elected, and to enable truly awful ones to be removed. FPTP is good enough.
3. Fiddling with the electoral maths is thinking too small. If you want to reform the system, and have a referendum on it, then a much more comprehensive reallocation of power between centre and edge is needed.

I’m not as impressed with Arrow’s theorem as a lot of people are – perhaps because I’m just more comfortable with better rather than perfect than my correspondent here is. Actually, having just been reading the wikipedia discussion, I have a couple of fundamental disagreements – notably that I don’t really have a problem with the notion that there is a potential case in which one “dictatorial” voter or coalition of voters decides the election. For a start, the whole point of an election is that the candidates try to secure the support of enough voters to win. Secondly, if who turns out to be the critical voter is random with respect to the demographic makeup of the electorate and not known in advance, there’s an argument that this would in fact be fair, in that it wouldn’t privilege any interest-group over any other. As it would be impossible to target them for campaigning purposes, politics would have to operate as if the system was formally fair in Arrow’s sense. Given the entrenched biases in the current system, this would in fact be a move towards justice.

Anyway, there’s nothing in Arrow to say that we should prefer a system that is pathological when it’s operating normally to one that is usually better but might have odd corner cases. It’s also ironic that economic libertarians get so hung up on Arrow when the same logic about Pareto efficiency is a well-known problem for free-market economics (making any given market more free doesn’t necessarily move the macroeconomy closer to full allocative efficiency).


  1. Apropos this “FPTP is imperfect but better than PR anyway” argument, Paul Sagar has a rather good review of James Forder’s “The Case Against Voting Reform – Why the AV System Would Damage Britain.”

    http://badconscience.com/2011/04/01/the-day-of-judgement/

    The review is long, but contains a precis of Forder’s argument.

    I found it persuasive, but YMMV…

  2. Rob

    The independence of irrelevant alternatives desiderata in Arrow also seems a bit dodgy to me. There are plenty of other processes which get morally appropriate results when information about options you’re not currently choosing over gets included. For example, when considering adultery, the fact that you did choose to marry your spouse seems relevant even though you’re not thinking about whether to do that now.




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