[EM] A rant about IRV and its recent history in Alaska

[robert bristow-johnson]

I agree with Greg Dennis that there is a lot to respond here.

> On 03/29/2025 2:26 PM EDT Steve Eppley <seppley at alumni.caltech.edu> wrote:
> 
> 
> RCV (a.k.a. Instant Runoff) clearly failed in Alaska in 2024 too. The Republican Party learned an important lesson from the fiasco in August 2022: RCV can easily spoil. So in 2024, one of the two Republican candidates who qualified for the general election dropped out to avoid the possibility of being a spoiler.

I don't know what their motivation is.  In Alaska November 2024, the Condorcet winner was elected with RCV.  That meant that the Spoiler Effect was avoided and that every voters vote were counted equally.

> And the one who didn't drop out -- Nick Begich -- had similarly pledged to drop out if another Republican finished ahead of him in the primary election.

Yeah, but here's the dumb thing.  August 2022 Palin *did* finish ahead of Begich.  Among the GOP Palin was preferred over Begich by more Republicans than the contrary.  But among Alaskans as a whole (which is what the general election is about), Begich is far preferred over Palin.  37000 voter margin.

But the mistake in August 2022 is that, among Alaskans as a whole Begich was preferred to Peltola by over 8000 vote margin.  Yet Peltola was elected with IRV.

> A lesson they haven't yet learned is that the kind of pledge that Begich made -- to drop out if another Republican finished ahead of him in the primary election -- can lead to spoiling too, because the candidate who drops out might be the one who could win in the general election.

And that's the problem.  That's the wrong lesson to be learned and IRV obfuscates the correct lesson.  Begich was the stronger GOP candidate, yet IRV propped up Palin against Peltola head-to-head and Palin was too weak.  Yet Begich would have beaten Peltola.  The GOP split their vote and RCV promises to resolve that split vote correctly and IRV didn't.  But Condorcet RCV would have resolved that split vote correctly.  Palin voters would have been able to safely vote for their favorite candidate had the election been decided with Condorcet-compliant rules.


> Suppose Begich had made that pledge ahead of the August 2022 election. Then he would have dropped out to avoid the possibility of spoiling Sarah Palin's victory. But it was Begich, not Palin, who a majority ranked over Democrat Mary Peltola in the August 2022 election.

Yes.  And RCV promises to solve that problem for us, but failed to in August 2022.

> (Peltola's majority over Palin was very narrow. That means RCV came close to electing the extremist.)

Peltola was preferred to Palin by about 5000 voters out of 188000.  Begich was preferred to Peltola by 8000 voters and preferred to Palin by a margin of 37000.




> We can expect the Democrats too will eventually learn the lesson that RCV is prone to spoiling. 

I would say that IRV is more prone to spoiling than is Condorcet RCV.  I think that's obvious.   For the case of a Rock-Paper-Scissors cycle, *any* method will demonstrate the spoiler effect.  If the method elects Candidate Rock, then Candidate Scissors *must* be a spoiler.

But Condorcet RCV would have saved Burlington 2009 and Alaska 2022 (August) from spoilage where Hare RCV (or IRV) failed to do so.

> Greg Dennis asks "why leave out the November 2022 election where RCV elected the Condorcet winner Peltola?" Because we're not claiming RCV always defeats the Condorcet winner.

That's right.  November 2022 didn't exhibit the Spoiler Effect as did August 2022.  But that might be that Begich voters mistakenly thought that Begich was weak and jumped ship onto either Palin's or Peltola's bandwagons.

>By the way, my definition of "spoiler" is narrower than RBJ's definition.  He calls X a spoiler if X, by running, causes the winner to change from some Y to some Z.  I call X a spoiler if both of the following conditions hold: (1) X, by running, causes the winner to change from some Y to some Z.  (2) The number of voters whose order of preference has X > Y > Z exceeds the number of voters whose order of preference has X > Z > Y.

>  In other words, X is a spoiler if X, by running, causes the election of a "greater evil" of most of X's supporters.

But that is always the case when IRV fails to elect the Condorcet winner.  Then the loser in the IRV final round is the spoiler.  At least in the case of 3 significant candidates.

It's because many more of Palin voters preferred Begich over Peltola.  Or in Burlington 2009, many more of Wright voters preferred Montroll over Kiss.  In both cases, many more of the voters for Candidate Right preferred Candidate Center over Candidate Left.  That is the Center Squeeze.

So your additional requirement adds no additional restriction.  When IRV fails and spoils an election, it is *always* the Center candidate who is robbed, which means the candidate on the Right or Left is the spoiler and the opposite candidate on the Left or Right is the beneficiary of the spoiled election.

>  We can also define a counterfactual spoiler: someone who would be a spoiler if s/he runs, but chooses not to run.  Similarly, we can define a counterfactual Condorcet winner: someone who would be the sincere Condorcet winner if s/he runs, but chooses not to run.

That's just so speculative that I don't feel safe speculating.

>Spoiling (which violates the IIA criterion) isn't necessarily bad.

It's always bad for a larger number of voters than the spoiling favored.  More voters suffered from the spoilage than voters who benefited.

>For instance, if Scissors by running changes the winner from Paper to Rock, the additional preference information gained when Scissors runs may suggest Rock is better than Paper.  In this case, we should hope Scissors isn't deterred from running.

Scissors has every right to run.  We must not deter Scissors from running.  But if Scissors is the spoiler (which is the case in a cycle and Rock is elected), it is simply in the numbers that Scissors running drew more 1st-choice support away from Paper than they did from Rock (and they would be Scissors' voters 2nd-choice votes).  That's how Paper got eliminated in the semi-final IRV round.

I still think that Greg needs to justify these two claims right on his front page, https://voterchoicema.org/ :

1. [Instant-Runoff] Voting Ensures Majority Support by eliminating the “spoiler effect” and guaranteeing the winner earns a majority of the votes in any election.

2. [Instant-Runoff] Voting Expands Voter Choice by freeing you to vote for who you really want, without settling for the “lesser of two evils,” and without fear of “wasting” your vote.

Both claims are shown to be false.  Proven false.  Why do you continue to state these claims without qualification, Greg, when we all know they're just false?  You're lying to your customers.

robert

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r b-j . _ . _ . _ . _ rbj at audioimagination.com

"Imagination is more important than knowledge."

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