[EM] Suppose, for a moment, there were never any cycles...

robert bristow-johnson rbj at audioimagination.com
Sun Jan 22 19:38:51 PST 2023

> On 01/22/2023 12:28 PM EST Kristofer Munsterhjelm <km_elmet at t-online.de> wrote:
> On 22.01.2023 10:08, robert bristow-johnson wrote:
> > On 01/21/2023 5:18 PM EST Kristofer Munsterhjelm <km_elmet at t-online.de> wrote:
> >>    
> >> If there is a CW, then IIA always holds, yes. Suppose X is the CW and Y
> >> is someone else. Then running the election without Y doesn't change
> >> anything: X still beats everybody else pairwise and wins.
> >>
> >> Thus if somehow you could prevent both sincere and tactical Condorcet
> >> cycles, the method would be strategy-proof. (Strictly speaking, this
> >> doesn't invalidate Arrow's theorem because a method that magically
> >> forbids Condorcet cycles would fail universal domain.)
> > 
> > Well I don't really expect to prevent cycles, but just by doing
> > nothing, I can plan on them being extremely rare, 0.2% of the time.  So
> > it's a faux-suppression of cycles, a pseudo-effect.  Either way, I can
> > say that the reason that IRV is good at avoiding the spoiler effect is
> > solely because 99.4% of the time IRV elects the Condorcet winner.  It's
> > as effective at suppressing the spoiler effect as it is effective at
> > electing the Condorcet winner.  FairVote has to credit any success they
> > claim for IRV to Condorcet.  Because when IRV fails to elect the CW, it
> > doesn't do shit about preventing the spoiler effect and all the
> > pathologies cascading from that failure to prevent the election from
> > being spoiled.
> Like Kevin, I would say it's worse. The way Plurality goes, after a few 
> spoiled elections, people figure out that they can't throw away their 
> vote by voting for a third party.
> For IRV, I imagine that the typical progression would be that IRV allows 
> minor parties to grow (since they don't affect the outcome), then a 
> viable three-way contest happens, and then IRV more or less becomes a 
> random draw. Then the voters either figure out that they have to 
> compromise after all (which leads back to two-party rule), or they 
> repeal IRV.
> But somehow, the step from small third party to three-way contest 
> doesn't seem to happen all that often in the US. I don't know why, but 
> whatever it is, it masks IRV's flaws.
> In any case, if people go back to two-party voting to protect themselves 
> from IRV's failures, then those 0.6% have an outsize influence -- just 
> like with Plurality.

The problem with repealing IRV to go back to plurality is that of a problem of education, misinformation, and even disinformation.  Alaska is not the same as Burlington, but right now they are going through some of the same drama we did in 2009/2010.  

There are the GOP persons somehow claiming that they were robbed.  At least in Burlington, they had something of a case by just appealing to plurality: "Whoever has the most votes wins."  But in Alaska those aggrieved GOP make no sense whatsoever because Sarah Palin never had the plurality of votes.  That is the one sense that the topology of failure in Alaska 2022 is different than that in Burlington 2009.  Otherwise the two elections look quite the same, with the center squeeze effect, the candidate on the right being the spoiler, and the candidate on the left being the beneficiary of a spoiled election.

In 2009, I was a voice crying in the wilderness.  We, in Burlington, were faced with a false dichotomy: Hare IRV or FPTP.  Pick the lesser of evils.  It's a little different now.  A third, smarter, alternative might be available.


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

"Imagination is more important than knowledge."


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