Let's found an organization to oppose IRV

Blake Cretney bcretney at postmark.net
Tue Nov 14 10:41:40 PST 2000

"MIKE " <nkklrp at hotmail.com>, on the subject of 'RE: Let's found an
organization to oppose IRV', is quoted as:
>I'd said:
>> >There are certainly a number of ways in which Plurality is better
>> >IRV. Participation, IIAC, Consistency, etc.
>Blake replied:
>>Saying that approval meets IIAC is meaningless, because the method
>>represent a full ranking of the candidates.  We therefore don't know
>>the voter would have voted with fewer candidates, even assuming
>I don't think IIAC is about how people would have voted in a different
>election with different candidates. I've heard people refer to that
>kind of an IIAC, but I've never heard a precise definition of it.
>Nor have I heard a claim that any method could pass such a criterion.

First, when I said that IIAC was meaningless for non-ranked ballots,
it's important to understand that I meant that in the sense of "an
election between two government appointees is meaningless", not in the
sense of, "the colour of sound is meaningless".

With that said, can you explain why anyone would care about whether or
not IIAC is passed by a non-rank ballot method, like plurality or

>> > For me, an important way
>> >in which IRV becomes worse than Plurality is when candidates'
>> >tapers gradually away from the voter median point, with the voter
>> >median canddiate having the most 1st choice support. That doesn't
>> >at all unusual or contived. In fact it sounds typical. And in that
>> >ordinary, typical scenario, IRV fails where sincere voting would
>> >fine in Plurality.
>>Obviously, if the CW gets a plurality of the votes, I agree that
>>plurality is picking the best winner.  However, you seem to be
>>that a gradual tapering will always result in IRV picking someone
>>different.  Is that true?
>Well, doesn't it seem so? First the extremes get eliminated, and
>transfer inward. Surely, if the taper is at all gradual, candidtates
>to the sides of the median CW will accumulate enough votes to
>elimiate the CW.

I'd have to think about that.  Remember that it isn't just the most
extreme parties getting eliminated.  Middle parties group together as
well.  When I have more time, I'll write a program to simulate this

Whether approval will do better seems to depend a lot on the
intelligence of the electorate, and the availability and accuracy of
polls.  With enough information, and proper strategy, any method will
give the sincere CW.  Approval allows the strategies involved to be less
extreme.  However, the prevalence of strategy in approval makes any
outcome seem possible, and allows for some very optimistic approval
examples.  Consider that both you and Bart advocate approval, and both
of you give examples showing how well approval does, but your examples
show how a CW would be elected where it wouldn't in other methods.  His
examples show how approval can keep CW's out if their average ratings
aren't high enough.  

On the other hand, it seems like many Americans (and I'm not implying
that Canadians would be better) seem to have enough trouble with a
plurality ballot.  I'm not convinced that the general public will
understand approval well enough to use it effectively.  Although they
probably won't misunderstand it quite so much as Mr. Davison has.

>>I certainly wouldn't argue that IRV is the best possible.  On the
>>hand, I wouldn't try to organize against the efforts of people trying
>>implement it.
>But I bet that would depend on how honest those IRVies are, and
>how sleazy their tactics are. Sure, if the IRVies were honest, I
>might not oppose them in the way that I do.

I'm not sure about "sleazy tactics".  I would agree that IRV advocates
often use a lot of specious arguments.  I put that down to legitimate
misunderstandings, though.  I don't consider it sleazy that the CVD has
chosen to advocate only IRV.  "Sleazy tactics" sounds like smear
campaigns, or brief cases full of money going to pay off congressmen.

>Criteria like MMC are usually defined so that either no method meets
>them, or so that even Plurality meets them. Here's how I define
>an MMC that isn't like that:
>If there's a set of voters, comprising a majority of all the voters,
>who all prefer every candidate in set S to every candidate not in S,
>and if they all vote sincerely, then the winner must come from S.

Why are you worried that plurality might meet the criterion.  Are you
concerned that someone might later take your criterion out of context,
and use it to defend plurality, even where this would be meaningless?

>But I always point out that IRV's MMC compliance doesn't count for a
>whole lot, because every MMC example is also an IRV badexample, where
>IRV fails the defensive strategy criteria.

Despite its pleasant name, I don't care about the "defensive strategy"
criteria.  However, in this example

46 D A B C -- A B C much lower rated
19 A B C D -- D much lower
18 B C A D -- D much lower
17 C B A D -- D much lower

IRV picks B.  Unless the A/B/C voters really get their act together, or
have some kind of primary, D will win.  If one of A/B/C does win, who
will decide which one?   A very small group of voters who were counting
on other people to make sure D lost.

Picking D is a failure of MMC and GITC (for a ranked method).  Is
picking one of A/B/C a violation of DSC.

Blake Cretney

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