[EM] STV's rejection: it's "not a defect, it's a feature!"
Craig Carey
research at ijs.co.nz
Wed Mar 15 18:37:32 PST 2000
At 10:36 15.03.00 -0800, Bart Ingles wrote:
>
>DEMOREP1 at aol.com wrote:
>>
>> Simple Approval Voting has the rather major defect of having a later
>> vote cancel out an earlier vote.
>
>That's not a defect, it's a feature! And it doesn't cancel out the
>earlier vote, since the earlier vote still counts against non-approved
>candidates.
>
>One benefit of not allowing the voter to distinguish between levels of
>approval is that the voter will not add a second vote unless she
>believes the compromise choice to be a good one. This avoids the
>situation that can happen with ranked methods, which can elect a
>candidate whom the majority feel is only slightly better than the worst
>possible choice.
...
The Approval Voting method, according to Mr Ossipoff, needs to be
considered undefined when this is not true: there are very few
candidates and only one winner is to be elected. Is that a viewpoint
of others, e.g. Bart?. It is bit like the gaps in the output winner
set of Condorcet, except that in the case of the Approval Voting
method, everbody knows what the definition is but defers to whatever
crumbs of assertions the authorities were able to give.
These Ossipoff restrictions making the method undefined of course
invalidated some of my arguments that FBC was badly undefined. Of
course, Mr Ossipoff still needs to add another constraint to FBC, and
one I suspected all along [I called it a "contrived" rule]: FBC is
a test for only one method, the Approval Voting method. He countered
my arguments about FBC by constraining the number of winners in the
Approval Voting method, apparently not realising that others thought
that FBC need not be test doing nothing more than supporting that
particular method. Let's un-cripple the Approval Voting method and
allow more than one winner (and then reject it). Why not also remove
the same constraint on FBC and reject that too, for being undefined.
All of which leads to a conclusion that a quality case defending the
Approval Voting has not yet been pulled off.
An authority on a new method should be allowed to undefine it. But
isn't that a move in the wrong direction?. Particularly during the
course of arguments when the authority was defending a position
against my arguments that definitions (FBC, and I should include SARC)
were not fully defined
Now the Approval Voting method is as far as I can tell, undefined
for greater than 0.9999999 [7 nines]
of all multi-winner [small-ish] elections that can be analyzed
mathematically. So it must be a practical persons method. It is a
dangerous idea in a society having uneducated voters. What is the US
illiteracy statistics?. I haven't been keeping up with those figures.
Couldn't be more that tens of millions?. Too many zeroes Mr Ossipoff
(Brams, anybody?: so it has to be a one winner method??).
PS. Maximizing some Utility value is an unclear thing since the
maximizing is done under constraints. With suitably selected
constraints, the aim can be a test that passes only the Approval
Voting method. So the idea of maximal utility values able to be of
not importance. E.g. suppose it was subject to a strict constraint
that proportionality (provided different), was first maximized.
Maybe Mr Ossipoff undefined the Approval Voting method by accident
and would like to recheck that previous attempt. After all, it was
couched in a personal desire/understanding framework (rather than
explicit and mathematical).
----------------------------------------------------------------------
Demorep1 seems to be favouring STV's truncation resistance, with the
use of the words, "major defect".
Demorep1's clone idea can be regarded to be a corollary of monotonicity.
Demorep1 and I discussed that in private.
While STV doesn't satisfy monotonicity, the 3 candidate Alternative Vote
goes a long way towards passing that test. It takes 21 papers. The
Approval Voting method does not, and it has this alteration example:
(A+)-(AB+); i.e. (A, A wins)<->(AB, B wins).
PS. What does that word "rank" mean?. What is a ranked preferential voting
method?.
Could Demorep1 comment on this: "That's not a defect, it's a feature!".
What is Demorep1's current tolerance for methods that allow subsequent
preferences to alter the win-lose outcome of earlier preferences?. (I
will call that truncation resistance. It is a property that STV
satisfies, as some books point out).
I prompt Mr David Catchpole and Demorep1 to tell us (or me), if it is
tolerable to allow that property to be not satisfied. I am suspecting
that people in the UK might regard a good test of supporting STV as
being actually supporting it. That is too much to hope for here.
People in the UK might be wondering who supports STV here. Instead the
test might better be: strict favouring of truncation resistance and
an opinion that monotonicity is important. [Some research into how well
STV performs wrt. a monotonicity test for say 8 candidates, perhaps has
yet to be done.]
That is a rather simple property and it of course allows most of the
other preferential voting methods presented here to be rejected. Not
just methods though, but also the arguments that STV is just too
complex. How can it be too complex when about all of the competition
got rejected?.
What of that Schulze method. Condorcet passes the test, as far as it's
paradox cycles allow: and I guess the best effort variants fail the
test. Might Condorcet reject the best of the 20th century variants
of that method? ... Did Condorcet set out principles that can test
other methods?.
More information about the Election-Methods
mailing list