[EM] Condorcet Criterion for plurality.

[MIKE OSSIPOFF]

Craig L. said:

>Mike wrote (in part):
>
> >Or does he have a general rule
> >for getting from the voted ratings (or rankings?) the information that
> >the voting system needs, and would, in real life, get from its own
> >ballots? If so what is that general rule?
>
>Okay.  Maybe I'm understanding it differently to Markus.  I haven't read 
>the
>literature he refers to, but I would think it was fairly straightforward.  
>A
>voter has a set of preferences (A>B>C) either sincere or insincere, it
>doesn't matter as long as those are the preferences a voter intends to vote
>(not strategic).

Wait a minute. You said it doesn't matter if they're sincere or
not. If so, why are you saying they aren't strategic? If they're
not sincere, then might not an insincere ballot be strategic?



>You posit that the preferences exist, even when they
>cannot be fully expressed (say, in Approval or Plurality).  The preferences
>of plurality voters would show that there can be a Condorcet winner who may
>not get elected under plurality.
>

Yes. "Sincere CW" has a meaning that's in terms of sincere
preferences, and a number of authors, including Merrill,
speak often about how well methods do at picking an SCW.

In Plurality, even if everyone voted sincerely, as I defined
sincere voting, an SCW can lose. Plurality therefore fails CC,
as do all nonrank methods. All pairwise count methods pass CC.

Mike Ossipoff





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