Applying those criteria

Mike Ositoff ntk at
Tue Oct 20 20:46:51 PDT 1998


Blake said:

> On Sun, 18 Oct 1998 02:20:02   Mike Ositoff wrote:
> >
> >David--
> >
> >As I said, though I hadn't stated it as a criterion, the
> >1st Choice Criterion, which says that no one should have to
> >not rank their favorite in 1st place, is, it seems to me,
> >the main goal of single-winner reform. Considering how many
> >people listed sincere voting as a most important standard,
> >I believe that many agree with me on that.
> >
> >So which methods meet that criterion?
> >
> >If it means that we should never have defensive strategic reason
> >to not rank our favorite alone in 1st place, over everything else,
> >then the criterion is met only by VA (for all pracatical purposes).
> >Not by any other method. Certainly not by Margins or IRO.

I'm going to check out this example later, and reply on it
tomorrow. But I'd like to reply to the rest of the letter now.
Of course if what I find out about the example changes my
other answers, I'll say so.

> 45 A C B
> 18 B C A
> 17 B A C
> 20 C B A
>    A   B   C
> A  X   45  62
> B  55  X   35
> C  38  65  X
> A wins.
> But if the C voters vote
> 45 A C B
> 18 B C A
> 17 B A C
> 20 B C A  -- insincere
>    A   B   C
> A  X   45  62
> B  55  X   55
> C  38  45  X
> So, the C first voters had a clear incentive not to vote themselves
> alone in first place.  In fact, I don't think any ranked method,
> or for that matter any method that truly has a "first place", 
> fully meets your criteria.

I'll check out your example & reply tomorrow.

> So why does Mike feel justified in saying that VA meets
> your criteria, for "all practical purposes".  Mike's pronouncements
> usually have a large number of unstated assumptions.  For example,
> he often says that a voter never needs to engage in a particular 
> strategy, when he actually means as long as the voter's favorite 
> candidate is the CW.  Of course, voters are unlikely to see it this

Not at all. I don't say that a voter's favorite is necessarily
the CW. But if your candidate can't beat the candidates you
like less than the CW, then it's in your interest to help the
CW defeat those less-liked candidates.

> way.  They want their candidates to win whether they are CW or not.

So what? Maybe that means that helping offensive strategy is
important to you, but it isn't of interest to me.

>> As well, he tends to assume that order-reversal will happen a lot in
> Margins, but never in VA.  This is because of his defensive truncation

Order-reversal isn't detered in Margins, without drastic defensive
strategy, as it is in VA. So, if it happens anywhere, at all, it
will happen more in Margins. And will cause Margins to fail
even the weak version of the 1st Choice Criterion.

But Margins' problems don't require order-reversal. Ordinary
common truncation, whether innocent or strategic, will require,
win Margins, drastaic defensive strategy that is quite unworthy
of a rank-balloting method.

> strategy.  I don't agree that this is a practical strategy, or one
> likely to be used.  We have exactly the opposite positions on
> the defensive order-reversal strategy.  If you want a full discussion
> on this issue, you should check past postings in this list.
> Many of Mike's comments are based on the fact that VA is more truncation
> resistant than Margins.  This is quite true.  If you remember how
> Condorcet methods work, a candidate wins not as much by maximizing the
> size of its victories, as by minimizing the size of its defeats.
> When someone votes   A > B = C, they are helping A by increasing the
> chance and size of B and C losses vs. A.  However, they are missing
> the chance to increase a loss for either B or C.  So, in VA, a more
> sensible vote would be either A > B > C or A > C > B.  Since in VA,
> you don't have to worry that this may decrease the size of a loss, 
> like in Margins.
> So, VA reduces the effect of truncation by punishing all voters who
> rank equally at the end of the ballot.  Hopefully, from this perspective,
> voters will rank candidates equally anyway, unaware that they are
> being punished for it.  Once they realize that random filling is the
> better way, the jig will be up.  Mike believes this isn't a problem 
> because it won't defeat a CW.

You've got it. I've carefully & repeatedly shown why it won't
be a problem for electing CWs. Many of us, Blake, consider the
election of CWs, with as litte compromising of our favorite,
is very important. Not you? Fine. As you said, we believe

> >And it's half-met by Approval, since at least one can vote
> >one's favorite as high as anyone can vote anything--no need
> >to ever vote anything over your favorite.
> You can eliminate the need for any strategy by restricting the voters
> expressed preferences enough.  I don't consider this a triumph.  If

Most would agree that not having to completely abandon your
favorite by voting a less-liked alternative over it is
a very desirable advantage. 

Of course the best possible methods use rankings. But if
they aren't counted well, we're really better off without them.
Rather like not letting kids play with dynamite or drive cars.
If we can't enact a good rank-method, then we're better off
without rank-balloting. Margins doesn't materialize any
of the benefit that rank-balloting makes possible.

> you only have two rankings, it doesn't make sense to rank a less
> favorite over a more favorite.  If you penalize equal rankings at
> the end of the ballot, truncation becomes a poor strategy.
> Remember that when Mike says something about Margins vs. VA, he may
> have a number of implicit assumptions.  You can't just take it at

I state my assumptions. You sometimes, as in this letter, mis-state
my assumptions.

> face value.  If you agree with all his assumptions, that's fine.  
> But if you don't, you should check his statements for yourself.
> Blake
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