[EM] Fwd: Is Condorcet The Turkey?

Kevin Venzke stepjak at yahoo.fr
Thu Jun 19 12:23:11 PDT 2003


 --- Dave Ketchum <davek at clarityconnect.com> a écrit : 
> So utility has SOME KIND of value which i have demonstrated I do not 
> understand.  How about letting me in on the secret.

Maybe you can understand it in terms of "strength of preference," where
multiple "greater-than" signs are used in place of worth values.  Perhaps
that will be more meaningful to you.

Imagine these as the SENTIMENTS (these are not ballots) of the voters:
49 A>>>>B>C
2 B>>A>>>C (doesn't really matter)
49 C>>>>B>A

The Condorcet ballots arising from the above sentiments:
49 A>B>C
2 B>A>C
49 C>B>A

Please do not reply to this by pointing out that no one ranks B last.
That is indeed a useful fact, but it has nothing to do with utility.

Looking at the SENTIMENTS it is evident that B is only barely preferred
to most voters' last choice.  If utility were measured as "the number of
greater-than signs placed to the right of the candidate among all voters" 
(which would certainly make sense), we see immediately that B would have
the lowest score.

Relevance to the prisoner's dilemma: If the A and C cooperate and agree not
to rank B>Worst, they gain a 50/50 chance of electing their favorite or
electing their least favorite.  If they don't or can't cooperate, they get
a 100% chance of electing a candidate barely superior to Worst.

So, if the A and C supporters can trust each other, they improve their
expectation by bullet-voting.  (But I don't think they will be able to
trust each other.)

Relevance to other methods: I've argued earlier that Approval would be
unlikely to elect B, because the Favorite>B preferences are much stronger
than the B>Worst preferences.

The fact that utility (strength of preference) isn't a big factor in Condorcet
elections, makes it an interesting point for comparison with other methods.
That is its value.


Kevin Venzke
stepjak at yahoo.fr


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