(Some background: I have worked with CES on an unsuccessful effort to get approval voting on the ballot in Denver and wrote a grant request for a campaign in Broomfield. Nowadays I mainly work on voting methods with the League of Women Voters and the Equal Vote Coalition.)
I agree with CES on basically every point mentioned here. However, I believe that it’s possible to have a greater impact in the voting methods area by focusing on voting methods other than approval—specifically, STAR and Condorcet methods. Part of this is because I think these voting methods do a better job than approval at electing optimal winners and incentivizing politicians, but I won’t belabor this point since CES agrees with me about STAR yielding slightly better winners than approval. Also, the difference between approval and the best possible single-winner voting method is smaller than the difference between approval and plurality, or even between approval and IRV (probably). The main reason I think we can have more impact by advocating for STAR or Condorcet is that I believe they are more likely to outcompete IRV nationwide if they are given the level of exposure that approval voting has received.
While approval is a better voting method than IRV, I believe that IRV looks better superficially. Ranking is more expressive than up-or-down approval, and intuitively it seems like a voting method that uses more data will yield better outcomes. Also, the argument that approval voting is vulnerable to strategic bullet voting (voting for only one candidate) gets a lot of traction, and voters don’t like feeling that they need to consider candidate viability or that strategic voting will decide elections. These arguments are flawed and Aaron has linked to some excellent refutations of them, but my point is that they are subtly flawed. Unless you dig into the topic enough to learn about things like the Burlington election, IRV is going to seem like the better option.
Such arguments are a lot easier to rebut when talking about STAR or a Condoret method. Both options are far more expressive than approval voting. Bullet voting is clearly a bad idea in STAR, and it takes a rather convoluted argument to make a case that strategic voting matters at all under Condorcet methods.
CES’s main argument for approval voting over methods like STAR and Condorcet is approval voting’s simplicity. But the simplicity of approval voting has a flip side: it’s also the least sexy of the reasonable voting methods. It’s a whole lot easier to get excited about ranking than about (maybe) approving multiple candidates—approval voting doesn’t feel like as big of a change.
I think sexiness is more valuable than simplicity or ease of implementation when it comes to getting a new voting method adopted. Before Broomfield’s city council debated between approval and IRV, the elections director gave a presentation that portrayed approval as providing basically the same benefits as IRV but at a much lower cost. Not a single council member even mentioned this advantage, and they unanimously went for IRV over approval voting. I expect voters to care even less about implementation costs than city councils. Altogether, approval voting ends up sounding like a cheaper and inferior alternative.
Even if simplicity is important, STAR voting can’t be too complicated to get enacted because IRV isn’t too complicated to get enacted and STAR is simpler than IRV. As for Condorcet, some Condorcet methods are also simpler and easier to implement than IRV. Condorcet methods have a reputation of being complicated enough to be incapable of catching on more broadly, but this reputation is entirely undeserved. As I’ve written here, Condorcet methods are uniquely positioned to take advantage of RCV’s momentum and can be far more acceptable to RCV advocates than approval or STAR.
In the two cities where approval voting is used, Fargo and St. Louis, it wasn’t technically feasible to use IRV. Also, they had some very impressive campaigns; in Fargo, my recollection is that the “Approval Voting Army” was bigger than either the Republican or Democratic campaigns, and St. Louis also had a huge force of volunteers distributing yard signs, sending texts, and doing other kinds of outreach. I think such strong groups of volunteers could have gotten just about any voting method enacted if it was technically feasible and had they opted to pursue it; these ballot measures didn’t succeed because approval voting is uniquely appealing.
Another big point for focusing on other voting methods is that having momentum makes it a lot easier to get a voting method enacted, and this means that there is far greater leverage in advocating for as-yet unused voting methods. If Seattle were to adopt IRV, it would provide a rather minor boost for IRV nationwide. If Seattle adopts approval voting it will be a far bigger deal—but probably not as big a deal as the victory in St. Louis since the difference between “used in Fargo, St. Lous, and Seattle” and “used in Fargo and St. Louis” is smaller than the difference between “used in Fargo and St. Louis” and “used in Fargo”. If Seattle were to adopt STAR or a Condorcet method it would a really big deal for those methods since it would actually put them on the map. The less known a voting method is, the more good we can accomplish by giving it its first victory.
I am not overwhelmingly confident that STAR and Condorcet have a better chance than approval of outcompeting IRV. I believe that it’s quite difficult to predict how well a particular voting method will perform in a statewide ballot measure based on theory and (maybe) a few local results and opinion polls, and CES’s views on the importance of simplicity may be correct. Operating under this uncertainty, I think the best thing we can do is to support all of these better voting methods at once so we succeed both in universes in which approval (but not STAR) can outcompete IRV and in which STAR (but not approval) can outcompete IRV. In addition to funding CES, I think it also makes sense to fund the Equal Vote Coalition. They focus primarily on STAR, but also support approval and Condorcet. I think it’s also important for groups like CES to endorse initiatives to adopt STAR voting when they appear on the ballot and to provide visibility so that local supporters can get involved.
I want to emphasize that I agree with Aaron far more than I disagree with him. While IRV is a real improvement over plurality, it’s still severely flawed and can fall flat on its face when it comes to delivering improvements like decreased polarization and ending the two-party system. I very much hope that approval voting will outcompete IRV; I just don’t think it will.
What you’re proposing is closely related to Michel Balinski’s system of Fair Majority Voting. Both systems get proportional representation while having a representative from every district and without any sort of at-large seats. I think your system can be thought of as a greedy approximation of Balinski’s, like how Sequential Proportional Approval Voting is a greedy approximation of Proportional Approval Voting. Fair Majority Voting should elect slightly better winners, but your algorithm is a lot easier to describe.
Warren Smith has criticized Fair Majority Voting while proposing something similar (which he also finds very problematic). Smith’s main objection is that it’s easy for tactical voters to unseat prominent MPs in what he calls “targetted killing”:
Your system also looks vulnerable to this—if tactical voters cause the NaziLoon party to get 5% of the vote in Trudeau’s district (compared to 1% nationwide) this would yield a relative vote share of 5, which should easily be enough to oust Trudeau. I think Smith overestimates the severity of this problem since it would be possible to enact a rule like “You don’t actually need to get elected in order to be the prime minister so long as you got at least 40% of the vote in your district”, but this is still a relevant consideration when there are other MPs that people want to remove. For example, if 10% of the electorate in each district was bigoted against a particular minority they could use this strategy to keep that minority out of parliament.