Blake C: Ranking Can Backfire

[Mike Ositoff]

Blake Cretney asked if, when a voter insincerely ranks some
lower choices between which he has no preferences, it can
backfire. Yes it can:

Say your sincere ranking would be:

A
B

...and you have no preference among the other 4 candidates.

When you vote the above ranking, A wins.

But then, say that you, & 1 other person who votes as you do,
decide to vote:

  A
  B
  C
  D
  E
  F

...ranking all the alternatives.

And say that  E's greatest defeat is by F. F beats E
101 to 100. Your 2 votes for E>F reverses that defeat. Now
it happens that E's next worst defeat is very slight, and,
in fact, now E is less beaten than A. E wins.

I'd expect that that could happen with any of the Condorcet
Versions that we're discussing.

Admittedly, it could of course happen whether or not your ranking
is sincere. Maybe you really do feel those preferences.

Well, it's a tradeoff of properties & problems. You choose the
properties that are most important to you, and accept any
problems that inevitablly go with those desired properties,
if you consider the desired properties to be more important.
I & others consider the desired properties of Condorcet to be
more important than a problem like the one I described here.

***

By the way, I took a look at my reply to your (Blake Cretney's)
letter about the advantage of truncating, and my wording looked
a bit contentious, almost. Though that could be because I'd
just finished replying to Don, it really seems to me that I
just wasn't evalulating my wording in that regard, and that
it didn't occur to me that it could sound contentious. Obviously
you haven't acted contemptuously, and there'd be no reason for
anyone to be angry. I just meant to discuss the isssue that you'd
raised, with no intent to use attitude-language. Disagreement is
never a cause for anger or defensiveness. Argument, in the
attitude-neutral sense of the word, constitutes much of the
discussion.

Mike Ossipoff