[EM] Cycles in sincere individual preferences and application to vote-col...

Adam Tarr atarr at purdue.edu
Mon Sep 6 11:46:53 PDT 2004


Paul Kislanko wrote:

>The reason I wouldn't have chosen E over B, C, or D on a ranked ballot 
>with A as an alternative is that B, C, D "trumped" E on every issue that 
>was not the single one that A&E agreed upon.

And yet, you already stated you would prefer E pairwise over any of the 
three.  So why, oh why, would you rank E below them?  In what meaningful 
sense do you rank any of those three over E?  Agreeing with them on more 
issues is irrelevant if the one issue you support E on trumps all others.

>But once A is out of the picture, there's one issue that E trumps B, C, 
>and D on. And if A&E are both out of the picture than my sincere ordering 
>of B, C, D could well change.

To which I once again ask, why?  Why does the existence or absence of 
another alternative change how you feel about B relative to C?  Note that 
even within a group, such reversal of preferences is not part of 
Condorcet's paradox.

>  My original point was that you can;'t infer that I prefer B>C from a 
> ballot that has A>B>C>D>E on it. If you ask me which I prefer of B and C 
> (only) I might say C sincerely because (in this example) C is the only 
> one that is both pro-gun control and anti-capital punishment.
>
>When both of those are covered by my first choice, I might rank C last 
>among B,C,D because of something else, like fiscal policy.

At which point, I would accuse you of being illogical.  Either you value 
the candidates' relative stances on fiscal policies more, or you value 
their relative stances on gun control/capital punishment more.  The 
presence of another candidate who may be great or terrible on both of these 
issues should not change your relative valuations of those issues.

>There's no reason to believe you can infer pair-wise wins from a ranked 
>ballot voting method.

Well, that's what folks have been doing since Condorcet's day.  You're 
welcome to question it, and I'm welcome to disagree with you.

-Adam




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