Here's an argument that IRV has a pretty bad track record.
I think this isn't a big concern in two-party systems, but: if two candidates were using such a platform to raise their funds (or if someone like you set up a widely-used platform for two candidates only), wouldn't this put those candidates at a big disadvantage in comparison to all other candidates?
I'm really wishing for a version of this which would be in a politician's active interest to use (and be in the interest of any pair of politicians to set up).
I agree that having a multi-party system might be most important, but I don't think IRV necessarily leads to a two-party system. For instance, French presidential elections feature far more than two parties (though they're using a two-round system rather than IRV).
Yeah, I know very little about multi-party systems in practice (IE why these specific countries have escaped the two-party dynamic). But it's plausible to me that there are a few exceptions but the overall gravity of a voting system still makes a big difference. Especially in places where a two-party system is already entrenched, it's plausible that IRV just wouldn't be enough to dislodge it.
It's also plausible to me that if we could do controlled experiments, we would see two-party systems arise a much higher percentage of the time in plurality-voting systems than IRV, or that it would take much longer to settle into a two-party equilibrium in IRV systems.
Also, considering French politics (and the politics of other places with multiparty systems), maybe getting rid of two-party systems is not so important as I initially thought -- it doesn't seem like multi-party politics is so much better in terms of sanity and quality of policy.
I think that approval voting has significantly more serious tactical voting problems than IRV. Sure, they all violate some criteria, but the question is how serious the resulting issues are in practice. IRV seems to be fine based on e.g. Australia's experience. (Of course, we don't really know how good or bad approval voting would be, because it is rarely used in competitive elections.)
I agree, and that's why I base my opinion mostly on the statistics, which seem to favor approval. Out of the different levels of strategic voting considered, IRV's worst-case scenario is worse than approval's worst-case, and IRV's best-case is worse than approval's best-case. Granted, they have an overlapping range.
Perhaps more importantly, STAR voting and 3-2-1 voting beat both pretty decisively. Score voting (aka range voting) is best in completely honest cases, but subject to strategy, becomes as bad as approval. STAR reigns that problem in (by introducing its additional runoff), compromising some value in the completely honest case for a better lower bound in the very strategic case. 3-2-1 does the same thing even moreso, making all the scenarios roughly equally good.
Granted, these are simulated statistics, not real-world elections.
IRV isn’t perfect either. It also fails important criteria, and it isn’t clear whether IRV results in less polarisation. Still, IRV seems clearly superior to plurality voting and has stood the test of time, so I think efforts to implement IRV are worth supporting. (Even the very simple step of adding a runoff between the top two candidates would be a significant improvement over plurality voting.)
I think one of the most important factors is whether a voting system favors a two-party system, for a few reasons:
This makes IRV a really bad choice. IRV results in a two-party system just like plurality voting does. Whereas plurality results in two parties due to the spoiler effect, IRV results in two parties due to "center squeeze", where moderate candidates get squeezed out by more extreme candidates -- so IRV may even result in more political polarization in the long run? (That's very uncertain, however.)
If we rule out IRV, then there are very few alternatives to plurality with much of a track record at all, and approval voting may even be in the lead in that respect. (Not sure.)
Approval voting is vulnerable to tactical voting. It fails the later-no-harm criterion: approving a second candidate can hurt your favourite. The average voter probably isn’t that strategic, but in high-stakes elections, savvy campaign leaders would surely attempt to get their supporters to vote tactically. The winner, then, may not be the candidate with the most support, but the one that’s best at manipulating the system. (See here for more details on this.)
Everything is subject to tactical voting (except maybe SODA? but I don't understand that argument). So I don't see this as a point against approval voting in particular.
Approval voting radically re-interprets the common-sense notion of "having a majority", leading to results that may be considered counterintuitive. This is reflected in the voting method criteria that approval voting fails. For instance, approval voting sometimes selects a candidate even though a majority of voters would, in a head-to-head contest, prefer any other candidate. (This is the Condorcet loser criterion.)
I find Condorcet very unappealing from a utilitarian standpoint. The Condorcet winner may not be the utilitarian-best candidate, but rather, a poor compromise candidate.
Consider the following electorate, with score preferences on an election A, B, C, D:
The utility totals:
B is the condorcet winner, but also the worst candidate overall.
Granted, the problem here is that the available candidates are quite poor, with no real compromise possible. But that goes back to my point about how we should avoid two-party systems like the plague, because they can put us in situations where there's no good compromise on the ballot.
Indicating support or opposition for each candidate is more expressive than just having a single vote, but it is still binary and does not allow voters to express more nuanced preferences between different candidates.
Approval voting is a special case of "range" or "score" voting, which opens up the possibility of more nuanced ratings. This allows us to get much closer to the utilitarian-best candidate when voters are relatively honest, although under dishonest voting it devolves into approval voting (because there's rarely (never?) strategic reason to use anything but the maximal/minimal score).
In general, my impression is that discussions of voting reform suffer from the problem that people tend to pick their favourite method and then cherry-pick one-sided arguments in favour of it. In particular, people overemphasise criteria that favour their method does well while ignoring or and downplaying problems. The Center for Election Science often talks about no favourite betrayal (which approval voting satisfies) and not much about later-no-harm (which it fails). FairVote doesn't talk much about no favourite betrayal and talks a lot about later-no-harm - because their favoured method (instant runoff voting) satisfies later-no-harm but fails no favourite betrayal.
I think the voting theory primer for rationalists is free of this problem (or nearly so); the author computes an average-case utilitarian score for voting techniques based on random election scenarios (scroll to the end of that 2nd link for the actual results), and finds that STAR voting ant 3-2-1 voting are essentially the best, achieving a far higher score than plurality. IRV, on the other hand, is one of the worse options.
Between STAR and 3-2-1, 3-2-1 arguably has a better chance at success, due to a simpler ballot and more intuitive selections. There's an argument to be made that STAR is simpler to explain (because STAR voting chooses candidates based on two steps rather than three), but STAR elections will sometimes choose the candidate with the worse total score (due to a runoff-like mechanism), which might upset and confuse voters.
(Basically, STAR voting adds a runoff step to score voting. The added step greatly reduces the potential for strategic voting, so the total scores will better represent the utilitarian outcome; but the runoff step means we don't necessarily choose the candidate with the best utilitarian score.)
Bayesian orthodoxy has often been compared to a cult. Here, we take the opposite perspective, comparing Bayesianism to a long-standing institution like the Catholic Church.
The protestant reformation created initial (and ongoing) unrest, including bloody violence. However, we take the view that the reformation improved social institutions generally, culminating in the industrial revolution. Hence, the reformation offers a model of high-leverage changes with dramatically positive consequences on the future.
The primary question, then, is effective instigation and agitation -- how does one create conditions ripe for Reformation? What are the preconditions to a modern Martin Luther, nailing a new 95 Theses to the door of Bayesianism and Effective Altruism?
Since the historical Martin Luther initially studied as a lawyer, but hated it, we recommend a critical study of the law as a starting point, including the naturalization of the social contract. This goes well with a general study of the failures of top-down optimization such as Bayesian/utilitarian public policy tends to favor.
The distribution of radical literature being an old standby of the instigation and agitation industry, we recommend the circulation of literature concerning radical probabilism, a doctrine which critiques the Bayesian update -- insisting that, while Bayes' Law correctly analyzes updating on a certainty, there is in fact no such thing as certain knowledge. Bayes' Law therefore never applies.
According to this doctrine, all we can say about the shifting nature of belief is that they should not be (unboundedly) Dutch Book -able. In particular, like financial markets, they should behave like a martingale -- at any time, the current betting value ('price') of any belief should also be a best estimate of its future value.
We also broadly recommend attention be paid to critiques of Bayesian orthodoxy, implying that we sit down and actually pay attention to various critiques of Bayesianism (Frequentist, and otherwise). For too long have we rested in complacency, accepting Bayesian dogma. The time has come to develop a better perspective.