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<body><div>Colin makes one argument for learning to live with the plurality winner when there is no Condorcet winner. But it is only part of the reason. Even if the social choice theorists could agree among themselves on one best (or good enough) solution to the riddle of cycles, politicians and the voting public would still not accept anything more complicated than Robert's draft bill, or -- possibly -- "choose the IRV winner when there is no Condorcet winner." (The latter only because IRV is already a somewhat familiar procedure.) The fact that the theorists cancel each other out is only part of this situation.</div><div><br /></div><div>Robert said earlier that there is a "political problem that <b><u>might</u></b> eclipse the technical problem" (emphasis added). I would say instead that the political problem absolutely eclipses the technical problem.</div><div><br /></div><div><span>--Bob Richard</span></div>
<div><br /></div>
<div>
<div>------ Original Message ------</div>
<div>From "Colin Champion" <<a href="mailto:colin.champion@routemaster.app">colin.champion@routemaster.app</a>></div>
<div>To <a href="mailto:election-methods@lists.electorama.com">election-methods@lists.electorama.com</a></div>
<div>Date 2/18/2023 1:42:36 AM</div>
<div>Subject Re: [EM] Hay guys, look at this...</div></div><div><br /></div>
<div id="x5dbd93ecadeb42b"><blockquote cite="dc96cd6c-c173-4a9e-dbf1-480a5337d53e@routemaster.app" type="cite" class="cite2">
<font face="Helvetica, Arial, sans-serif">I think Robert was wise to
propse Condorcet+FPTP. It's the Judgement of Solomon, allowing him
to step aside from endless debates about which Condorcet method is
best.
<br />
I don't agree with his reasoning "If a simple majority of
voters mark their ballots preferring Candidate A over Candidate
B... Why should B be elected?" This is the argument of the
Condorcet Loser Criterion, which implicitly assumes that a
decision can be determined purely by the signums of the margins,
ignoring their amplitudes. Minimax violates Condorcet Loser and
I'm not the only person to support it.
<br />
But then I don't favour Kristofer's proposal either. My
evaluation suggests that burial is a particular threat for
Condorcet methods, and that in its presence their accuracies are:
minimax 64%, condorcet+fptp 59%, copeland,fptp 48%. [Usual
disclaimers apply.]
<br />
<br />
[I would say a word in favour of SPE with an FPTP preranking. This
is a symmetrisation of the method of Llull's De Arte Eleccionis of
1299, so it's essentially the oldest Condorcet method in existence
which isn't vitiated by indecisiveness. Its virtue lies in its
linear-time countability, which is only a factor if counting is
manual and there is a risk of a sizeable number of candidates
standing. SPE is about as resistant to burial as is minimax.]
<br />
<br />
Wiser judgements than Solomon's are imaginable. If there was a an
expert consensus that among those methods simple enough to gain
the approval of voters and legislators, XYZ was best, then Robert
would probably listen; but the onus is on experts to build a
consensus, not on advocates to take sides.
<br />
<br />
CJC<br />
<br />
</font><br />
<div class="moz-cite-prefix">On 18/02/2023 06:05, Forest Simmons
wrote:
<br />
</div>
<blockquote type="cite" cite="mid:CANUDvfrekM+i32SwTQsBwOeG09vOS_KxaGS-uA_tLTHr0Touyw@mail.gmail.com" class="cite">
<div dir="auto">Let me rephrase the question ... suppose that
there were only three candidates and you already knew that they
were in a rock paper scissors pairwise preference cycle.
<div dir="auto"><br />
</div>
<div dir="auto">How would you decide which one to vote for if
you could only vote for one?
</div>
<div dir="auto"><br />
</div>
<div dir="auto">That's the one you should make your first choice
on an RCV ballot if the cycle breaker is FPTP as you have been
suggesting.
</div>
<div dir="auto"><br />
</div>
<div dir="auto">That decision is at least as difficult as the
approval decision would be, because under approval strategy
you should approve that candidate X (the one you would vote
for if you had only one vote) AND also approve your favorite
if X was not already your favorite.
</div>
<div dir="auto"><br />
</div>
<div dir="auto">These are the same candidates that you would
naturally rank on an RCV ballot ... leaving the 3rd choice
unranked ... the one that is neither your favorite nor your
compromise.
</div>
<div dir="auto"><br />
</div>
<div dir="auto">If you mis-triangulate the compromise in an FPTP
election ... too bad: you wasted your vote. But the approval
ballot also counts towards everybody you like better than your
compromise, including your favorite.
</div>
<div dir="auto"><br />
</div>
<div dir="auto">That's why Approval is often proposed as a
Condorcet completion method in the absence of a runoff.
</div>
<div dir="auto"><br />
</div>
<div dir="auto">Implicit approval takes advantage of the natural
strategy of truncating the candidates you don't like, while
ranking your preferred of the two front runners AND anybody
you liked better ... including your favorite ... whether or
not it was a frontrunner.
</div>
<div dir="auto"><br />
</div>
<div dir="auto">Yes, the cycle is already there ... but it
cannot split the votes unless the method allows vote splitting
by not having any contingent backup vote. Approval has the
simplest backup vote capability ... any other method requires
some kind of runoff/elimination step to ameliorate the
potential vote split.
</div>
<div dir="auto"><br />
</div>
<div dir="auto">Example ballot profile:</div>
<div dir="auto"><br />
</div>
<div dir="auto">40 A>B (Sincere is A>C)</div>
<div dir="auto">35 B>C</div>
<div dir="auto">25 C>A</div>
<div dir="auto"><br />
</div>
<div dir="auto">Under Plurality A wins.</div>
<div dir="auto"><br />
</div>
<div dir="auto">The Implicit Approval (fewest truncations)
winner is B with only 25 truncations, compared with 35 A
truncations and 40 C truncations.
</div>
<div dir="auto"><br />
</div>
<div dir="auto">This is a typical kind of ballot profile
resulting from the burial by the largest faction ... of the
sincere Condorcet Winner (C in this example).
</div>
<div dir="auto"><br />
</div>
<div dir="auto">If the C supporters wanted to protect C, they
could have truncated A:
</div>
<div dir="auto"><br />
</div>
<div dir="auto">25 C instead of 25 C>A.</div>
<div dir="auto"><br />
</div>
<div dir="auto">This would not change the Plurality winner, but
reinforces the Implicit Approval winner, which gives the
sincere CW a defense against burial by punishing the burying
faction ... electing their sincere last choice instead of
their sincere second choice.
</div>
<div dir="auto"><br />
</div>
<div dir="auto">With this defensive truncation B still has the
fewest truncations 25, but now the burial perpetrator A has
way more truncations (60) than either of the others ... no
chance of success in their burial gambit.
</div>
<div dir="auto"><br />
</div>
<div dir="auto">Electing the Plurality choice (lacking a ballot
CW) rewards the burial perpetrator in this example .... so it
encourages candidates with large first place support to bury
the sincere CW.
</div>
<div dir="auto"><br />
</div>
<div dir="auto">This example is typical in this respect ... the
insincere burial (of sincere CW) gambit is most tempting to
the faction with the greatest first place support.
<br />
</div>
<div dir="auto"><br />
</div>
<div dir="auto">On the other hand it is not tempting to bury the
CW when lacking a CW the implicit approval candidate is
elected ... because this burial gambit will almost certainly
fail if not outright backfire.
</div>
<div dir="auto"><br />
</div>
<div dir="auto">It seems to me that anybody who understands why
Approval is superior to FPTP Plurality as an election method
... such a person should be able to see how Approval is a
better fall back alternative than Plurality (absent a CW) ....
an appreciable positive difference at no extra cost.
</div>
<div dir="auto"><br />
</div>
<div dir="auto"><span style="font-family:sans-serif">The little
Dutch boy was right to put his finger in the dike ... a
stitch in time is in deed worth nine.
</span><br />
</div>
<div dir="auto"><br />
</div>
<div dir="auto"><br />
</div>
<div dir="auto"><br />
</div>
<div dir="auto"><br />
</div>
<div dir="auto"><br />
</div>
<div dir="auto"><br />
</div>
</div>
<br />
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Fri, Feb 17, 2023, 7:07 PM
robert bristow-johnson <
<a href="mailto:rbj@audioimagination.com" moz-do-not-send="true">rbj@audioimagination.com</a>>
wrote:
<br />
</div>
<blockquote class="gmail_quote" style="margin:0 0 0
 .8ex;border-left:1px #ccc solid;padding-left:1ex
"><br />
<br />
> On 02/17/2023 9:44 PM EST Forest Simmons <<a href="mailto:forest.simmons21@gmail.com" rel="noreferrer" moz-do-not-send="true">forest.simmons21@gmail.com</a>>
wrote:
<br />
> <br />
> <br />
> Suppose the whole election was to choose one of the three
candidates ... no noncycle members were in the election at
all.
<br />
> <br />
> Would you recommend FPTP Plurality over Approval?<br />
> <br />
> <br />
<br />
I dunno. I would recommend Condorcet RCV and, only in the
super-rare case of a cycle, I would recommend plurality of
first-choice votes because it's no worse than we already have
now with FPTP and it's simple to explain to voters why that
one candidate (the one with more first-choice votes than
anyone else) is, in some sense, uniquely more preferred by the
electorate over any other candidate.
<br />
<br />
In a competitive 3-way race, I dunno if Approval would be
better than FPTP. I *do* know, if it were Approval, that I
would have a tactical decision to make regarding my
second-favorite candidate.
<br />
<br />
But with RCV, I would have no tactical decision to make. I
would know immediately what I would do with my second-fav.
<br />
<br />
--<br />
<br />
r b-j . _ . _ . _ . _ <a href="mailto:rbj@audioimagination.com" rel="noreferrer" moz-do-not-send="true">rbj@audioimagination.com</a><br />
<br />
"Imagination is more important than knowledge."<br />
<br />
.<br />
.<br />
.<br />
</blockquote>
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