Approval

MIKE OSSIPOFF nkklrp at hotmail.com
Mon Feb 28 08:17:38 PST 2000




>Are people writing to this list advocating some "Approval Vote" method?.

Yes. But it it isn't a question of some Approval method; there's
one method called Approval: Same as Plurality except that each
voter may give one vote each to any candidate(s). As with
Plurality, the candidate with the most votes wins.

>Isn't it one of the very worst methods around?.

No.

Approval is one of the very best methods around. Only Condorcet
& Bucklin are better, by defensive strategy standards. That
makes Approval the 3rd best method. Bucklin isn't being proposed
now by anyone, and so it can be said that Approval is the
2nd best current proposal, by those standards. By "Bucklin",
I mean the class of methods that includes Bucklin and the various
ordered-Bucklins, including Davison's RWE. By "Condorcet", I mean
the whole class of methods that qualify as Condorcet versions.

Who told you that Approval was one of the worst??

Approval, along with Condorcet & Bucklin, is one of the few methods
that meet WDSC, the Weak Defensive Strategy Criterion, which
is in the process of changing its name to NonDrastic Defense
Criterion (NDDC):

If a majority of all the voters prefer A to B, then they should
have a way of voting that will ensure that B can't win, without
any member of that majority voting a less-liked candidate over
a more-liked candidate.

I've mentioned the methods that meet NDDC. Methods that fail
it include IRV (aka The Alternative Vote, Preferential Voting,
Majority Preferential Voting, etc.); BeatsAll//IRV; Schulze(Margins),
Tideman(Margins); Borda;...and pretty much any other method.

***

These 2 criteria are met by Approval, and by no other method:

Favorite-Betrayal Criterion (FBC):

By voting a less-liked candidate over his favorite, a voter should
never gain an outcome that he likes better than any outcome that
he could get without voting a less-liked candidate over his
favorite.

***

Strong Adverse Results Criterion (SARC):

If a group of voters share the same preferences, and if they
all vote the same way, in a way that could, with some configuration
of the other people's votes, produce an outcome better than any
outcome that they could get in any other way, then the fact that
they showed up & voted in that way should never cause their
favorite to lose, or cause their last choice to win, if that
wouldn't have happened had they not showed up & voted.

***

FBC & SARC are met by no method except for Approval.

***

As I said, I personally prefer Condorcet's exclusive criterion
compliances. Or, putting it in more direct terms-- Approval
makes good use of previous elections, and will quickly home in
on the median candidate or party, but Condorcet will usually
go directly to the target in its 1st election. Also, I
like the luxury of being able to rank, with respect to eachother,
the candidates whom I'd vote for in Approval, as I can do in
Condorcet or Bucklin. Additionally, with Condorcet, if the
voters aren't devious, or if anti-reversal enhancements are
in effect, or if the likely CW isn't my favorite & we're allowed
to rank as many candidates as we want to, then I can also
rank, with respect to eachother, the candidates I wouldn't vote
for in Approval.

***

Far from being one of the worst, Approval is the 2nd best
voting system proposal. Something to consider especially if
you find that it's difficult or decades-time-consuming getting
a good rank method adopted. I'm not saying it will be, but
if so there's an interim reform that would bring immediate
improvement.

***

Mike Ossipoff







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