New Sightline article by Kristin Eberhard
This is a new post by Kristin Eberhard.
I'll respond to some of it here.
> Political scientists and mathematicians have come up with many criteria by which to evaluate voting systems, resulting in complex tables like this one. But as Nobel prize winner Kenneth Arrow proved, no system can satisfy all criteria.
This is false. Arrow's Theorem says nothing about satisfying "all" criteria; it specifically refers to three specific criteria. And Arrow's Theorem only applies to ordinal (ranked) voting methods, so cardinal (rated) systems such as Score Voting and Approval Voting do in fact satisfy his criteria.
> The Institute for Democracy and Electoral Assistance has a tool that translates criteria into priorities and selects the best voting systems for you based on your stated priorities.
This general way of thinking is fallacious. It's kind of like evaluating race cars by stating how much you value horsepower vs. drag vs. weight. What you care about is: How fast will this car complete a race? What voters really care about is: How satisfied will I be with the elected office holders with this system? It turns out we have an objective way to measure that, called Bayesian Regret. Thankfully this is briefly mentioned by the Wikipedia article Kristin linked to, but it is astonishing that she didn't mention it directly in a discussion about how to assess the quality of various systems.
Now that's not to say that "externalities" like cost or political viability (which aren't captured by Bayesian Regret) are irrelevant. But this kind of analysis needs to be grounded in science first and foremost. The same would be true of a complex topic like climate change. You start by understanding the science and the ideal policy, and then you incorporate practical considerations. If you don't get the ideal right, then the practical considerations are of much less importance. Who cares about the political viability of the wrong policy?
> Under Instant Runoff Voting, it is always safe to rank a weak third-party candidate like Nader.
This is simply false. Even a weak candidate can change the order of elimination, leading to a major change in the final outcome. E.g.
33% LePen > Macron
32% Macron > X
35% X > Macron
Macron is preferred to LePen by a huge 67% majority here, and preferred to X by a huge 65% majority. But thanks to vote splitting, Macron is the first eliminated.
LePen is the Condorcet loser—the weakest candidate. But if some LePen supporters insincerely rank Macron in first place, then he wins—which helps them get their 2nd choice instead of their 3rd.
And the bigger issue here is that you do not know ahead of time exactly what's going to happen. This is why Green supporters often vote Democrat under the present system, even if the Democrat ends up with a margin of victory that would have made it safe to vote sincerely. They did not know exactly what would happen. They just knew that a vote for Green was more likely to be a spoiler than to help them.
> For example, if you ranked Terry Tea Party first, Larry Libertarian second, and Ronald Republican third, your vote would count for the Tea Party candidate in the first round; if she was eliminated, your vote would transfer to the Libertarian;
Not if the Libertarian was eliminated before the Tea Party.
> In extremely rare cases—0.7 percent of Instant Runoff Elections in US cities—IRV creates a “center squeeze” situation
It doesn't matter that it's rare. You're failing to understand basic statistics here. It's also rare for a third party candidate to be a spoiler in our present system. But people vote strategically because of the relative probability of "Green is a spoiler" vs. "Green wins".
This is explained in great detail by a math PhD here if these relative probabilities aren't clear and obvious enough to you.
> All of these systems suffer from a flaw voting experts call “Later-No-Harm”
Okay, this statement makes it clear Kristin is not acting as an objective researcher but more of a pro-IRV salesperson. Because there's a strong case that it's a flaw to satisfy Later-no-harm.
> When voters realize this, they often “bullet vote” (only score or vote for their favorite candidate among the perceived frontrunners).
"Among the perceived frontrunners"?! Are you telling me that a Green who votes Democrat and Green is "bullet voting" because the Green isn't one of the perceived frontrunners? Are you now suddenly redefining the term "bullet voting"?
In any case, this whole bullet voting argument is specious and deceptive based on empirical data.
> Experience suggests that most voters using Approval and Score give their favorite candidate the maximum score or rank and all other candidates a minimal score or no vote.
That is an outright lie, as the previous link showed. Also...
Great counterexample from a high stakes election. (A poll, but a heavily contested one.)
> Score Runoff Voting should, in theory, encourage voters to give a maximum score to their favorite and also a score to their second-favorite
Only your first and your second? This is simply false. You want to top-rate your favorite frontrunner, even if she's your 3rd, or 4th, or 5th (etc.) overall favorite. The runoff component of SRV makes this even more so, since distinguishing between the candidates is how you have influence in the second round.
> Different people have different ideas about who the “most right” winner is. The candidate whom a majority of voters support? The candidate whom most voters would choose over any other individual candidate in a head-to-head race? The candidate the fewest voters strongly object to (even if that also means that fewer voters strongly support him)? The candidate whom voters most strongly adore, even if many voters object?
This implies it's subjective, when in fact you can apply logic to this question and get an objectively correct answer.
> Score Voting would likely lead to even more negative campaigns than Plurality Voting.
Wow. Just, wow.
As far as I'm concerned, this goes beyond legitimate disagreement. This is outright anti-scientific Rovian FUD.