[EM] To James A., about Bucklin & ERIRV

[Markus Schulze]

Hallo,

the Minnesota Supreme Court wrote:
> The preferential system [Bucklin] directly diminishes the right of an
> elector to give an effective vote for the candidate of his choice. If
> he votes for him once, his power to help him is exhausted. If he votes
> for other candidates he may harm his choice, but cannot help him.

James Green-Armytage wrote (9 April 2004):
> I have to agree that Bucklin's later-no-harm failure is a big deal. I
> think that it's much much worse than the later-no-harm failure of wv
> Condorcet, since there needs to be a cycle for a later choice to harm
> an earlier choice. I'd say that the later-no-harm problem is Bucklin is
> somewhere in the same league as the same problem in Borda (*gasp!*),
> which is pretty darn bad. Basically, the truncation incentive in
> Bucklin is "off the hook." So I think that the court was right on that
> one.

I interpret the decision of the Minnesota Supreme Court as follows:

   Bucklin is unconstitutional because it violates later-no-harm and
   satisfies later-no-help. In other words: When Bucklin is being used
   then ranking an additional candidate sometimes hurts but never helps
   already ranked candidates.

Since Condorcet methods violate both later-no-harm and later-no-help,
I don't think that the decision of the Minnesota Supreme Court can
be applied to Condorcet methods.

Markus Schulze