[EM] vulnerability to compromise?

[Markus Schulze]

Steve wrote (13 May 2000):
> Markus wrote (12 May 2000):
> > Steve wrote (11 May 2000):
> > > Markus wrote (10 May 2000):
> > > > It can be argued that -in the Schulze method- if some
> > > > voters uprank D ahead of A or downrank A behind D then
> > > > this means that candidate A becomes less popular and that
> > > > it is therefore legitimate when candidate A loses the
> > > > elections.
> > >
> > > That's a flawed argument. Candidate A is not really less 
> > > popular; it merely appears that way if one trusts the
> > > sincerity of the votes.
> > 
> > Mike wrote (12 May 2000):
> > > But (rhetorical question) if compromising means insincerely
> > > voting someone higher to make him win, then how could that be
> > > considered something that shouldn't work, or something that
> > > means that a method has a vulnerability fault if it works?
> > > If "vulnerability to compromise" means that, with a method,
> > > it can sometimes be necessary for a voter to insincerely vote
> > > someone higher in order to prevent the election of someone
> > > worse, then "vulnerability" seems the wrong word.
> > 
> > I have to agree with Mike.
> > 
> > It is understandable that if some voters rank a candidate
> > higher then this candidate might win ("compromising"). And
> > it is understandable that if some voters rank a candidate
> > lower then this candidate might lose ("burying").
>
> I agree with Mike too.  Mike's statement and mine are not 
> contradictory.  
>
> And Mike's statement does not support Markus' argument shown at 
> the top of this message.  The voters manipulating Markus' Feb 3 
> 2000 example, if the Schulze method were employed, would be 
> electing their favorite, not a compromise.

Mike's statement and mine are not contradictory. And Mike's
statement does not support Steve's argument.

As far as I have understood Mike correctly, he says that
(1) burying and compromising are problems, but (2) that it isn't
wrong if voting someone higher can make him win or if voting
someone lower could make him lose and (3) that it would be
therefore more problematic if the winner could be changed
with other strategies and (4) that it is therefore not a
"vulnerability fault" when an election method can be manipulated
by burying or compromising.

Therefore Mike's statement is in drastic contrast to Steve's
claim that the existence of a "direct" strategy (e.g. burying
or compromising) is worse than the existence of an "indirect"
strategy (e.g. changing the winner from candidate A to candidate
B by ranking candidate C insincerely ahead of candidate D).

Markus Schulze
schulze at sol.physik.tu-berlin.de
schulze at math.tu-berlin.de
markusschulze at planet-interkom.de