Which is better, First Past The Post or Alternative Vote? A lot of people are arguing about exactly that, and as well as spouting all the usual bullshit, I think they’re getting quite a long way ahead of themselves. First, we need to define “better”. I think it boils down to this:
Your best strategy should always be to stand for election, and failing that, to vote for candidates in the order that you like them.
It turns out, though, that it’s much more complicated than that, to the point that there’s a whole branch of mathematics just for this. So, there’s already a list of criteria that good electoral systems should satisfy. They have fancy names and, because I think this stuff is interesting, I’ve paraphrased a few from Wikipedia:
- The Condorcet (Winner) Criterion: if one candidate would beat each of the other candidates in a two-way poll, this candidate must win the election.
- The Condorcet Loser Criterion: if one candidate would lose to each of the other candidates in a two-way poll, this candidate must not win the election.
- The Consistency Criterion: imagine splitting the constituency in two. If both new constituencies would elect the same person, that person should also win in the real election.
- The “Independence Of Clones” and “Independence of Irrelevant Alternatives” Criteria: if a candidate joins the race who is a clone of an existing candidate or who isn’t going to win, it must not affect the result.
- The Monotonicity and Participation Criteria: in different ways, these essentially say that a candidate must never lose an election because you voted for them.
Now you have to decide which you think are important. You can’t have all of them. But decide now.
I think consistency is nice, but not a deal-breaker. Independence of clones and of irrelevant alternatives are pretty important. Everybody loses when a crap but distinctive candidate wins because several competent but similar ones split the sensible vote. I think the others, though, are really important. You can’t have someone lose an election despite being more popular than every other candidate. You can’t have someone win an election by being less popular than every other candidate. And you sure as hell can’t have someone lose an election who, had you not voted for them, would have won.
You may have different opinions about the above. Again, I encourage you to decide now, because in a moment I’m going to tell you which voting systems satisfy which criteria. No cheating, now.
Here are the ‘answers’:
|First Past The Post||Alternative Vote|
I don’t know about you, but this table surprised me. I’d have got the left column pretty much bang on, but I honestly thought that Alternative Vote would get a tick for “independence to irrelevant alternatives”, and I was utterly convinced it would pass the Condorcet winner test. I was dead wrong. That Alternative Vote failed on the last two criteria was less surprising, since I’d never considered them before, but still a major shock — under the new system, you might be better off not voting! Sure, a vote for a rank outsider is a bit of a wasted trip under First Past The Post, but at least it won’t do any harm. Under AV, it just might.
Looking outside the two options we’ll be given in May, is there any system that won’t punish me for voting or for standing for election? Well, no. Range Voting seems pretty good — it fails the Condorcet criteria, but only when the preferences are so close it arguably shouldn’t elect the Condorcet winner — but nobody’s invented a voting system that ticks all the boxes above. It may well be impossible. I said this stuff was interesting, not uplifting.
I really thought this post would be strongly defending Alternative Vote, but now I don’t know what to think. I still think AV is better than First Past The Post, but I’m not thrilled with either. I think Alex Foster’s case on the Pod Delusion, that a vote for AV sends the right message to politicians, and that anyway AV is a useful first step towards genuinely better, multi-member or proportional systems, is the clincher. If we have any form of Proportional Representation, it’s much less important if the local MP is arguably not the most popular one on the ballot.
The main point, though, is that it matters how we ask the question. There have been four polls about AV. In three, the actual referendum question was used:
At present, the UK uses the “first past the post” system to elect MPs to the House of Commons. Should the “alternative vote” system be used instead?
All three said that voters would slightly prefer AV. The fourth poll, by YouGov, used this question:
The Conservative-Liberal Democrat government are committed to holding a referendum on changing the electoral system from first-past-the-post (FPTP) to the alternative (AV). At the moment, under first-past-the-post (FPTP), voters select ONE candidate, and the candidate with the most votes wins.
It has been suggested that this system should be replaced by the Alternative Vote (AV). Voters would RANK a number of candidates from a list. If a candidates wins more than half of the ‘1st’ votes, a winner is declared. If not, the least popular candidates are eliminated from the contest, and their supporters’ subsequent preferences counted and shared accordingly between the remaining candidates. This process continues until an outright winner is declared.
If a referendum were held tomorrow on whether to stick with first-past-the-post or switch to the Alternative Vote for electing MPs, how would you vote?
In this poll, “no” won. The anti-AV Labour MP Tom Harris summarised this as
Not meaning to patronise the general public, but I think Harris has massively overestimated their grasp of game theory. You may notice that support for AV was not much lower in YouGov’s poll than in the others. Certainly not enough to account for the increase in opposition to the change. Harris presumably thinks that around a fifth of the people who hadn’t previously thought about AV have read this précis, usefully evaluated the proposals, and decided, on balance, that monotonicity and participation are too valuable to lose. I think they’re just put off by long-winded explanations. It sounds complicated and offers no obvious benefits. It isn’t even obvious that it works at all. Nobody would support AV based on that synopsis except logicians and the insane. You might say I’m underestimating the public, but I include myself — I totally misjudged AV when given roughly the information in YouGov’s question.
In short, having a referendum on a question of algorithm design is a terrible idea and nobody would do it if they honestly thought it mattered a damn whether we use Alternative Vote or First Past The Post, but luckily, it doesn’t. They’re both total pants. Neither reliably elects the most popular candidate, both can be manipulated, and both promote unhealthy two-party dominance. Ignore the maths. Ignore the pros and cons of what you’re actually being asked about. None of that matters. For once in your electoral life, you’re free! Vote for ideology. Vote for vague emotional ideals of “hope” and “change”. Vote with your heart.
Because that’s how this result is going to be treated in Westminster and in the media, and because fuck it, you might as well.