I'm Voting For Ranked Choice, But I Don't Like It

by jefftkjefftk1 min read20th Sep 202012 comments

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Voting TheoryPolitics
Personal Blog

This fall, Ranked Choice / Instant Runoff Voting (IRV) will be on the ballot in Massachusetts. I'm voting for it, but only because it's better than the status quo, not because I think it's a very good voting system.

Massachusetts currently uses traditional majority ("first past the post") voting: whoever gets the most votes wins. Unfortunately, this only works well when you have two candidates. With more candidates, the candidates tend to hurt their allies by competing for the same pool of votes, making it more likely that an opponent wins.

In IRV each voter lists their preferred candidates in order, and if your first choice is eliminated then your vote goes to your next favorite. This mostly fixes the problem of minor spoiler candidates: anyone who is not a serious contender will get eliminated and their votes redistributed.

Unfortunately, IRV has major problems when you have more than two serious candidates. For example, even if there is a candidate that a majority of voters prefer to every other, they can still lose if their competitors happen to be eliminated in the wrong order. In Why Ranked Choice Voting Isn't Great I give examples of realistic situations in which IRV can give poor results.

While every voting method has cases it handles poorly, some are better than others. One attempt to compare them is called Voter Satisfaction Efficiency (more details). The idea is, you run a large number of simulations and see how different methods perform. It turns out that IRV does very poorly here, and if voters are highly strategic IRV does even worse than traditional plurality voting.

While I wish the voting method for us to consider were Approval (or maybe 3-2-1 or STAR), I do still think IRV is better than what we have today, and I'm planning on voting for it. One specific way in which IRV is an improvement is that it mostly doesn't, in its failings, benefit one type of party. This means that if we switch to IRV, and then as third-party candidates become stronger contenders we start to run into IRV's problems, it should be politically practical to switch to a better system. I do think there is some risk of setting back alternative voting systems in general by implementing an inferior version, but on balance I think the benefit of fixing the "minor spoiler" problem is likely larger.

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IRV advocacy confuses me greatly. First past the post voting is the worst voting system in widespread use; instant runoff is bad, but not as bad. Approval voting is actually good. I don't think either of these facts is seriously disputed. Why, if you're going to switch voting system, would you switch to one that's merely less-bad, rather than switch directly to the best one? Why sabotage your voting-reform movement by choosing something that people will be right to hesitate about?

For the same reason as voting in the known-to-be-worst system; those are the options on the table. There is no mechanism where you pass on a poor reform in exchange for a better reform later; the choice is only ever pass reform now, or lose reform completely for a generation or two.

I cannot detect any relationship at all between the goodness of a reform and whether or not it gathers support. If there were a natural relationship between goodness and support, how is it the bad system was ever instituted in the first place, and now needs reform?

Consider also: if a less-bad voting system is instituted, it becomes easier to implement yet another even-less-bad voting system.

It's not clear to me that this lens is more valid than the opposite. Sure, passing up reform now could mean no reform for a while- but one could argue that in the absence of any reform, frustration and pressure is maintained, meaning the conditions for reform continue to exist, whereas doing inferior reform makes a large portion of people say either "Yes, we got reform, so now we should be happy", or "Hey, we already tried reform, and it ended terribly. Why are they demanding we try it again?"

Lock-in effects are real, and I am concerned that settling for IRV will lock a barely-better system in place, when the conditions are currently ripe for a truly decent system to be implemented

I am sympathetic to your view, I have just never seen anything like it happen in practice.

The problem is that getting voting reform on the ballot requires a huge, focused effort in money and personnel. Once it hits the ballot, win or lose, the money is spent and the overwhelming majority of the people will leave. This is because, at least in American politics, they are either volunteers (temporary) or contractors who fulfill a specific function on a campaign-by-campaign basis (temporary) or an alliance of several orgs with related goals (temporary).

The reason it is IRV rather than Approval here is because IRV has a bigger and more established support base, with more money. This is mostly because IRV is older than Approval and is basically the only option with which regular people might be familiar. There isn't an option available for putting a truly better system on the ballot, because there is no reservoir of money and personnel behind it.

If your frustration hypothesis were correct, then we would consistently see failed reform attempts rapidly replaced with superior reform attempts that succeed. But this isn't the case, as far as I can tell. While I have not done research on this question I am a closer-than-average observer of politics, and I observe that when reforms come up repeatedly they aren't improved. Instead, they are either basically the same (Net Neutrality, sugar subsidies) or differently-bad (encryption legislation, tax reform). All of these options are backed by large institutions, which can sustain a continuous effort over years and decades.

"Hey, we already tried reform, and it ended terribly. Why are they demanding we try it again?"

This is exactly how people usually react when a big reform push fails.

A "Yes on 2" board member posted a response on the FB side of this discussion: https://www.facebook.com/jefftk/posts/10100184817106872?comment_id=10100184909856002

Summary:

  • IRV has more of a track record which is useful for convincing people to support it

  • "later-no-harm" matches real preferences well

Why would you prefer Approval over IRV? I'm Australian, where we use IRV, and I'd find it significantly harder to work out who to vote for under Approval. Most voting examples I've seen (including jefftk) seem to have a small number of candidates, whereas here, in any seat that's not safe, there's at least 10+ candidates (where probably half I'd think about approving, but if I do that, then we're basically back to a 2-party system, meaning that Approval is worse than IRV in reflecting my preferences), let alone the 100+ candidates for a senate seat (which is multi member, but is sufficiently close to IRV that treating them the same from a voter decision view is reasonable). I can see the advantage of a Condorcet method over IRV (I know the Debian project uses it for elections/project votes), but approval seems only slightly better than FPTP.

What matters is not how well your ballot reflects your preferences, but how well the outcome matches the preferences of the electorate. IRV can have very strange results where when a candidate starts to get more support it actually hurts them (http://zesty.ca/voting/sim/) and if voters/campaigns are strategic you can get worse outcomes than first past the post (http://electionscience.github.io/vse-sim/VSE/)

I guess the thing I'm questioning is how well does Approval actually reflect the preferences of the electorate. Let's use Melbourne as an example: it was a safe Labor seat, but is now controlled by the Greens (there a useful summary of the seat's history at https://www.abc.net.au/news/federal-election-2016/guide/melb/ ). Under Approval, Liberal voters (who know their candidate isn't going to win, and want to deny Labor the seat) would vote for the Greens over Labor (e.g. approve Liberal and Greens); Greens voters would only vote Greens (they definitely won't vote Liberal); Labor vote Labor (as adding the Greens to the their vote only weakens their candidate). If the Greens win, Liberal voters can switch to Labor next election (causing more division); or if Labor wins can continue forcing Labor to spend resources on the Melbourne electorate—in both cases the result isn't reflecting what people actually want, rather the number of people following how-to-vote cards (are how-to-vote cards a thing in the US/outside Australia?). IRV has the same problem, except due to the problem of choosing whether to approve a candidate or not (vs giving all preferences), people are more likely to follow the how-to-vote card from the appropriate party (which is going to be governed by strategic voting, meaning you're getting more false information about the elecorate's preferences). It's also much harder to vote against someone under Approval, such as happened against Stephen Conroy ( https://www.pcworld.idg.com.au/article/355744/what_would_it_take_unseat_conroy_/ has some information, but I recall there were websites devoted to providing information about how to vote against Conroy — this would be much easier now since there were changes in the senate ballot in 2016).

It seems to me that there are a lot of times where people vote in our societies. In many cases people don't spend much time thinking about voting systems and simply go for the default in their country. 

To the extend that some states implement Instant Runoff Voting you create a situation where there's no default anymore and where there will be more discussions about what voting systems to use in other context as well. That socializes people towards having those discussions and towards it being normal to have different voting systems. Diversity of voting systems is valuable for the broader movement of voting reform.

IRV is an extremely funky voting system, but almost anything is better than Plurality. I very much enjoyed Ka-Ping Yee's voting simulation visualizations, and would recommend the short read for anyone interested.

I have actually made my own simulation visualization, though I've spent no effort annotating it and the graphic isn't remotely intuitive. It models a single political axis (eg. ‘extreme left’ to ‘extreme right’) with N candidates and 2 voting populations. The north-east axis of the graph determines the centre of one voting population, and the south-east axis determines the centre of the other (thus the west-to-east axis is when the voting populations agree). The populations have variances and sizes determined by the sliders. The interesting thing this has taught me is that IRV/Hare voting is like an otherwise sane voting system but with additional practically-unpredictable chaos mixed in, which is infinitely better than the systemic biases inherent to plurality or Borda votes. In fact, if you see advantages in sortition, this might be a bonus.

I like Ping's simulations a lot! The two main problems with it are that by representing voter preferences as a plane there will always be a condorcet winner (when a lot of the weirdness and voting systems comes down to how they handle the cases when there isn't one) and that assumes voters always vote their true preferences (when a lot of the weirdness in voting systems comes from strategic voting).

What are your opinions on STAR vs majority judgement?

To me, when I was reading about the different voting systems at the time of the last election in my country I recall majority judgement was a very clear winner. So I'm surprised to not see it mentionned here.