[EM] "Beatpath GMC" compliance a mistaken standard?

Kevin Venzke stepjak at yahoo.fr
Thu Jan 15 17:54:13 PST 2009

Hi Chris,

--- En date de : Jeu 15.1.09, Chris Benham <cbenhamau at yahoo.com.au> a écrit :
> Kevin,
> You wrote (12 Jan 2009):
> "Why do we *currently* ever bother to satisfy
> difficult criteria? What do 
> we mean when we say we value a criterion? Surely not just
> that we feel 
> it's cheap?"
> When simultaneously a criterion's satisfaction's
> cost falls below a certain 
> level and  its failure reaches a certain level of 
> absurdity/silliness  I start to
> lose sight of  the distinction between "important for
> its own sake" and "very
> silly not to have because it's so cheap".
> Mono-add-plump (like mono-append)
> is way inside that territory.  

I see. I don't think I value criteria for this sort of reason. If I insist
on a criterion like Plurality, it's because I don't think the public
will accept the alternative. And these two criteria are relative, so
that in order to complain about a violation you have to illustrate a
hypothetical scenario in addition to what really occurred.

I can't see what's so highly absurd about failing mono-append. It's
basically a limited case of mono-raise, and one that doesn't seem
especially more important. Is it absurd to fail mono-raise?

> "If you need to identify majorities, then the fact
> that a ballot shows
> no preference between Y and Z, is relevant
> information."
> In my view a voting method *doesn't* need to
> specifically "identify majorities", so it
> isn't. (The voting method can and should meet
> majority-related criteria 'naturally'
> and obliquely.)

But we aren't even talking about voting methods, we're talking about
sets. You have basically criticized Schulze(wv) even though it naturally 
and obliquely satisfies majority-related criteria.

> >But even if  the quasi-intelligent device is mistaken
> in treating them as
> >relevant, then that is a much more understandable  and
> much less serious a 
> >blunder than the mono-add-plump failure.
> "Ok. I still don't really see why, or what makes
> the difference."
> Imagine the quasi-intelligent device is the captain of  a
> "democracy bus" that takes
> on passengers and then decides on its course/destination
> after polling the passengers.
> Imagine that as in "situation 1" it
> provisionally decides to go to C, and then as in 
> "situation 2" a group of new passengers get on
> (swelling the total by about 28%) and 
> they are openly polled and they all say "we want to go
> to C, and have nothing else to say"
> and then the captain announces "in that case I'll
> take the bus to B".
> Would you have confidence that that captain made rational
> decisions on the most
> "democratic" (best representing the
> passengers' expressed wishes) decisions?
> I and I think many others would not, and would conclude
> that  the final "B" decision
> can only be right if the original "C" decision
> was completely ridiculous. Or would you
> be impressed by the captain's wisdom in being properly
> swayed by the new passengers'
> indecision between A and B?

However I answer doesn't make any difference, because the question is
why this crosses the boundary of clear badness while failures of 
mono-add-top and Participation do not. You have to write a bus story
that illustrates a mono-add-top failure but which seems intuitively
more reasonable.

> "Anyway, you already said there was no way to explain
> why it isn't
> completely absurd for Mutual Majority to behave as it does.
> I don't
> think that whether Mutual Majority's behavior is absurd
> should depend
> on whether you remember that Mutual Majority has this
> behavior."
> I mistakenly thought the question was redundant and
> answered too hastily. I withdraw
> my statement and instead just say that for the time being I
> can't think of one.


> "Never mind ....that real elections don't award
> divisible pies."
> Can I take it then that you no longer like 
> "CDTT,Random Ballot", which does award
> a probability "pie"?

Sure. Does your question mean that this really is how you view the
difference between CDTT and Mutual Majority, is in terms of the candidates
of the winning set sharing a probability pie?

> >"This is a negative because it suggests that your
> >positional criterion will be self-defeating."
>> >How can it possibly be "self-defeating"? 
> What
> >is there to defeat?
> "I thought there was some intention behind your
> criterion. You talk about
> the "clearly strongest candidate" so I assumed
> this idea is important to
> you."
> Yes, by "strongest" I mean  "voted
> strongest on presumably sincere ballots".
> "If insisting on electing the "clearly strongest
> candidate" creates incentives that *change* 
> who this candidate is, then what have you
> accomplished?"
> The criterion/standard is an end in itself.  Not
> everything is about the strategy game.
> Higer SU with sincere voting and sparing the method
> common-sense  (at least) difficult 
> -to-counter complaints from the positional-minded are
> worthwhile accomplisments.

This strikes me as an unusual amount of paranoia that the method's
results can't be explained to the public's satisfaction unless it's
similar to Approval.

> "I would say that I don't think the CDTT is that
> much more valuable, than
> the combination of MD and SFC, especially if you use
> pairwise definitions
> of these two."
> Doesn't SFC also bar C from winning in my
> "situation 2" election?

Yes. I'm just saying that defending the CDTT, with everything that it
implies, isn't my preference, and I may not be doing justice to it. If
it were sufficient for purposes of the discussion, it would be better to
discuss SFC.

> >Well since Condorcet is incompatible with LNHarm, that
> >doesn't explain why Condorcet fans should like it.
> "I don't agree. There are various degrees to which
> Condorcet methods fail
> LNHarm."
> I think that like FBC, LNHarm's value is greatly
> reduced if it isn't an absolute
> guarantee. 

I agree, when it comes to trying to sell a method to others.

> To me more valuable than either LNH by itself is
> that they both be
> in balance. If they can't be in balance I prefer the
> LNHarm problem to be 
> worse than the LNHelp problem.  In other words I dislike
> random-fill incentive
> much more than truncation incentive.

I think the WV methods are in decent balance here, at least when voters
are informed.

> >25: A>B
> >26: B>C
> >23: C>A
> >26: C
> >100 ballots (majority threshold = 51)
> >
> >B>C 51-27,   C>A 75-25,   A>B 48-26.
>> >In Schulze(Winning Votes), and I think also in any
> method
> >that meets "beatpath GMC" and mono-raise, the
> 26C truncators can 
> >virtually guarantee that C be elected by using the
> "random-fill" strategy. 
> >That is silly and unfair.
> "They have to vote for A,.."
> With no change to the other ballots, only 4 of the 26C
> ballots have to change 
> to C>A for Schulze(wv) to elect C (even if  the other
> 22C change to C>B).
> "They have to vote for A, and the B voters have to
> give those C 
> preferences, which they shouldn't (if they have the
> same quality of
> information as the C voters)."
> The only "quality of information" these C voters
> need is that the method has
> a 0-info random-fill incentive.

I wonder if there is a simple way to see that it really has this

I didn't realize your complaint about unfairness pertained to the
zero-info situation. Still, perhaps the unfairness is to the voters
who have actual preferences and can't sincerely truncate or random-fill.

Kevin Venzke


More information about the Election-Methods mailing list