To Blake, re: strategy

[Blake Cretney]

MIKE OSSIPOFF wrote:

 > Blake said:
 >
 > Some countries use plurality with successive elimination for things like
 > leadership conventions. I think Americans use it for speaker of the
 > house. Since the strategy is very similar, I think that awareness of
 > strategy in one would be good evidence of awareness of strategy in the
 > other.
 >
 > I reply:
 >
 > Sure, but there are also countries that use IRV, and that's obviously
 > the best evidence about IRV in action.

So do you think IRV's strategy problems are worse than successive
elimination?  If not, then a lack of strategy in successive elimination
has to be taken as evidence of a lack of strategy in IRV.  It's almost
the same the method.


 >
 > I'd said:
 >
 >>
 >> information from (2 by e-mail, one in person), none of whom know
 >> eachother, told me that it's common for preferrers of small parties
 >> to insincerely vote one of the big-2 parties' candidates in 1st place
 >> , to avoid "wasting their vote". One of those Australian voters with
 >> whom I spoke had just voted in that way in the most recent election.
 >> But they all said that such voting is common in Australian IRV
 >
 > elections.
 >
 > Blake replied:
 >
 > I don't consider those people a representative sample.
 >
 > I reply:
 >
 > Fine. Do a proper scientific statistical study. In the meantime,
 > the evidence that I've described is all that's been offered from
 > Australia.

We obviously have different opinions on what constitutes good evidence,
and if anyone is still reading this discussion, they'll have their own 
opinion.

 > Rob has quoted some results from Ireland that confirm
 > IRV's spoiler problem, a problem closely associated with LO2E.

 >
 > I might also add that when IRV was adopted in Australia it was hoped
 > that it would encourage parties to run more than 1 candidate per
 > party. For the most part that hasn't happened.

Well, I'm not the all-around IRV apologist.  I would point out some
problems with IRV myself.  I was adressing the narrow point of whether a
significant number of people use the compromising strategy in IRV.

 >
 > Blake continues:
 >
 > As well, their
 > strategy does not appear to be rational.
 >
 > I reply:
 >
 > Excuse me for repeating this, but you may have missed it before:
 >
 > Say there are 3 candidates, Favorite, Middle, & Worst.
 >
 > Say Middle is closer to Worst than to Favorite. Hardly an implausible
 > assumption, since it's unlikely that Middle is exactly in the middle.
 >
 > Say that Favorite isn't expected to have a 1st choice majority. Not
 > implausible either, since, if the candidates are roughly equal in
 > 1st choice support, none has more than about 33% of the total
 > 1st choice support.
 >
 > Now, if Favorite is your favorite, should you sincerely rank Favorite
 > in 1st place? Why? Favorite can't win, based on our assumptions.
 > If you rank Middle in 1st place, at least you might save Middle from
 > immediate elimination, avoiding an avoidable Worst victory.
 >
 > Not only is insincerely ranking Middle in 1st place a rational
 > strategy, but it's the only rational strategy for someone who
 > prefers Favorite>Middle>Worst.

I agree that strategy would be rational in that situation.  I don't
disagree with the principle that strategy may be rational in IRV (in
fact I discuss this on my web site).  It's just that the few times I've
heard people quoted as saying that they favour strategy in IRV, they
don't seem to understand it.  They seem to believe in a plurality-style
strategy of compromising towards the major parties.

 >
 > Blake replies:
 >
 > It's quite possible to want to avoid having people vote candidates equal
 > to their favourites without advocating Strong FBC. Just as it is
 > possible to want to reduce crime without believing in some unmeetable
 > zero-crime criterion.
 >
 > I reply:
 >
 > Ok, so you're just saying that it's good to be able to guarantee
 > that _sometimes_ voters won't regret that they didn't insincerely
 > rank someone equal to their favorite, and that they sometimes won't
 > regret that they didn't insincerely rank someone over their favorite.
 >
 > Sorry, but guarantees that contain the word "sometimes" or "maybe"
 > don't sound very reassuring.

 >
 > I think what you're getting at is that, while Approval never gives
 > any incentive to vote someone over your favorite, it routinely gives
 > strategic need to rank someone equal to your favorite. In comparions,
 > methods like IRV & Ranked-Pairs(margins) sometimes _do_ give strategic
 > need to vote someone over your favorite, but at least they
 > sometimes don't give strategic need to vote someone equal to or
 > over your favorite. And you consider that an advantage for IRV &
 > Ranked-Pairs(margins) over Approval. Is that it?
 >
 > For you, "sometimes" is good enough a guarantee. You have a gambling
 > nature.

If that was my argument, I wouldn't agree with it either.  Saying that
IRV "sometimes" doesn't give strategic need to vote someone equal to or
over your favourite couldn't be used to justify anything.  My argument
was in terms of general tendencies.

 > Blake continues:
 >
 > [regarding insincere equal-voting]
 >
 > I don't think ordinary voters have much of an opinion on it, because
 > they've never heard of approval. When they do get involved, they seem
 > to be drawn to IRV far more than approval, based on the strength of the
 > movements.
 >
 > I reply:
 >
 > Here there's lots of money paying for IRV promotion. And the IRVies
 > are promising people that IRV will end the lesser-of-2-evils problem.
 > So of course that sounds good to people. People are misled to believe
 > that IRV won't give incentive to rank insincerely.

It seems to me that you make much of the argument that the public is on
your side, but when it is pointed out that this is not the case, you
declare that they are just hapless dupes.

 >
 > Blake continues:
 >
 >> Once again, I never mentioned strong FBC. But as for your question, I
 >
 > think that a criterion should be judged by what passing it implies. We
 > know (or suspect) that a method that passes FBC will be at least as bad
 > as approval on the equal-voting issue, unless it is one of the peculiar
 > strategy-free methods.
 >
 > I reply:
 >
 > You're just saying that one must choose between different
 > desired properties. The fact that different desiderata are
 > incompatible doesn't discredit either. It just means that one must
 > choose.

But a criterion isn't just a desired property.  It's a pass/fail test.
  If I think that the failers are better than the passers, I don't think
much of the criterion.

 >
 > You like the gamble of maybe not regretting that you didn't
 > insincerely equal-rank, or bury your favorite, and sometimes
 > regretting that you didn't bury your favorite. Approvalists prefer
 > the absolute guarantee of never having any incentive to bury one's
 > favorite, in comparison to your guarantee that you sometimes won't
 > regret that you didn't equal-rank or bury your favorite.
 >
 > You suggest that most people tend naturally to like your gamble
 > too. We don't know that, since most IRV-convinced people have only
 > heard from the IRVies. If you're right, then we must offer a rank
 > method. If so, then we can offer them a better one than RP(m). But
 > many prefer the advantages of Approval. And Approval is so much
 > easier to implement, and is so much less of a radical change from
 > FPTP, that Approval is likely to be more winnable than a rank method.
 > The rank methods are completely new voting systems, were they to
 > replace FPTP. Approval isn't a completely new voting system, just
 > an obvious improvement, a big voter-freedom improvement, on the
 > old Plurality. Unlike RP(m), also, Approval doesn't add new
 > disadvantages, like failure of Participation, Consistency, IIAC,
 > Heritage, & Regularity.

But you yourself must repudiate most of these criteria.  I mean, a
criterion like consistency is based on the idea that it doesn't make
sense for a method to behave in a particular way.  But wouldn't you
agree that that is false, and sometimes it does make sense for a method
to violate consistency?

 >
 > Blake continues:
 >
 > In the same way, a method that passes IIAC will
 > either not accept full rankings, or discard most of them. So, even
 > though IIAC may sound good, I think that it is actually bad for a method
 > to pass it, since it implies other things that are not good.
 >
 > I reply:
 >
 > That's a bizarre thing to say. What you mean is that, while
 > passing IIAC is a good thing, you feel that methods that don't
 > pass it have other advantages that you consider more important.
 >
 > Methods that don't pass IIAC might pass CC, SFC, GSFC,
 > &/or SDSC. But IIAC is compatible with FBC & SARC, as are
 > Participation, Consistency, Heritage & Regularity.

Well, I don't care about any of those criteria (except the Condorcet
criterion).  I don't support any criterion unless I can think of a
good justification for supporting it.

---
Blake Cretney
http://condorcet.org