Hello James,

On Sep 9, 2005, at 03:56, James Green-Armytage wrote:


Juho, you write:
I'm very much in favour of trying to achieve consensus on what
Condorcet methods to promote in public.

        I don't see why this would be necessary. You don't need the consent of
self-selected internet list participants to lobby for a change in the
voting system of any particular group. Instead, you need the consent of
that particular group, or at least a majority thereof. If you are forming
an advocacy organization, you might want to agree on a party line, but
this list in itself is not an advocacy organization.
If you want to lobby for a particular method, go ahead and do it; don't
wait until everyone on an internet list agrees with you. If you want to
discuss the relative pros and cons of different methods, then IMO this
list is a good place to do it.

I agree. Although I used term "promote in public" I'm not involved in any lobbying and I support keeping this list as a tool for neutral studying. I'm thus a strong supporter of "pros and cons" style discussion. The practical usability of various methods however falls within my preferred scope of the list. (I think discussing or sometimes even praising the properties of minmax or DMC or any other method to other members of this list should not be counted as "lobbying" here.)

However, now that I've done my share of complaining, I would be curious
about which methods each list member "supports", or "approves of", or
"consents to". To that end, I've created a quick and dirty wiki poll. I
hope that it sees some use. Feel free to stretch the structure of it if
you like.
http://wiki.electorama.com/wiki/Method_support_poll
        By the way, the method evaluation poll is still ongoing:
http://wiki.electorama.com/wiki/Method_evaluation_poll

Good, this type of activities are always welcome (although I personally often have problems in finding clear answers to the questions if they are multiple and detailed and if questions don't exactly match my thinking patterns :-).

I mean that with sincere votes the best winner
may be found outside the Smith set at least in some type of elections
(that seek for a nice non-hated consensus candidate)
...

The basic example and question is if A losing to B, C and D (all three)
by 51-49 is worse than A, B and C each losing to one of the others by
66-33. Minmax picks A as the winner but Smith compliant methods pick A,
B or C.

        I see no reason to think that the size of the majority against a
candidate is an indicator of how "hated" they are. If you are interested
in consensus, I suggest that you use approval voting (or something
similar) rather than a Condorcet method.

I don't see the connection between approval and consensus to be that strong. I think rankings can equally well be used to describe consensus - in a different way. I'd say that electing e.g. a candidate that has received no first place votes but is ranked second by most voters could be called a consensus candidate. Now when I think about this, the definition of Condorcet winner is actually quite close to defining a "consensus winner" (based on available pairwise comparison information).

Condorcet is IMO essentially a
majority rule principle rather than a consensus principle.

=> Unanimous majority in pairwise comparisons. I think it also has the characteristics that it tends to elect "consensus candidates" like I described above. I'm not a native English speaker, so I may not know the use of word consensus in English language well enough, but for me anything that talks about acceptability to or agreement by all (or many) (instead of dominance of the strongest one(s)) is OK (also approval).

Thus I consider
MMC-failing Condorcet methods to be awkward.

We discussed MMC and Smith in March under title "majority rule, mutinous pirates, and voter strategy". This time I asked only if Smith should always hold (since that case is easier :-). I assume that your earlier position is still valid and you want both MMC and Smith to be always respected (tell me if not).

MMC is majority related but I don't derive its validity straight from Condorcet. I believe quite firmly that Condorcet should hold in all ranking (only) based methods (both in the sincere case and most likely no reason to give that up for strategical defence reasons either). Since March I haven't made much progress in any direction with my MMC thinking. I tend to think that MMC is quite strongly strategy related. I.e. it doesn't say much about who would be the best candidate to elect but it says that certain voters would have the option to improve the result of the election (from their point of view) if they would agree how to vote strategically.

It is possible to construct examples where the mutual majority prefers candidates that beat each others badly but are still considered all good by the mutual majority (sort of clones or own party candidates). In this case it would make sense to elect one of the mutual majority preferred candidates. But unfortunately ranking based votes do not give us that information. Thus I feel that more information would be needed to make the judgement whether the mutual majority should be allowed to exclude those candidates that they mutually dislike or not (I'm talking about sincere utility of the community as a whole, and excluding strategic considerations).

MMC has some more sense than Smith, but not enough to drop minmax from my favourites list (of methods that provide good utility with sincere ranked votes at least).


my best,
James


Still waiting for someone to agree that Smith is not always required :-).

BR, Juho

P.S. For those who want, it would be possible to construct methods that meet MMC but fail Smith.

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