[EM] Chris: Regarding the criteriion "failures" you mentioned for MMT

[C.Benham]

Mike,

In an earlier message of yours (the last one I responded to) you wrote:

> MAMT is an addition to the list of FBC/ABE methods to choose from. 
> People should be looking into its properties. Tell me what you know, 
> so far, about its properties, ...


That is almost the only thing I did. You didn't ask me to confine myself 
to properties that I personally think are *important* or to explain why 
I think they are important.

> You said that MMT fails Later-No-Help:
>
>  With MMT, you can help your favorite by entering into a mutually-chosen,
>  mutually-supported, majority coalition. Everyone supporting that 
> coalition
>  does so because they consider it beneficial to their interest.
>
>  How is that a "failure"??


I assume you know what the criterion specifies and are asking me why 
meeting Later-no-Help is a good thing.  Failing LNHelp while meeting 
LHHarm creates a random-fill incentive. One of the problems with that is 
that is unfair to sincere truncators. Why should they be penalised for 
declining to play silly games with candidates they don't care about?

Another is that all methods that fail LNHelp are vulnerable to Burial 
strategy.

> You said that MMT fails Mutual Dominant 3rd:
>
>  I don't know what that criterion is.

It is a weakened version of Smith that is compatible with LNHelp 
compliance (and so Burial Invulnerability) and also compliance with 
LNHarm. It says that that if there is a subset S of candidates that on 
more than a third of the ballots are voted strictly above all the 
outside-S candidates and all the S candidates pairwise-beat all the 
outside-S candidates then the winner must come from S.

 From your recent past statements I know I don't have to sell the 
desirability of compliance with this to you. I gave this example:

49: A
48: B
03: C>B

I can't take seriously any method that doesn't elect B here. Can you?  
Isn't this just the sort of small (probably wing) "spoiler" scenario 
that motivates many to support electoral reform?

> You said that MMT fails Mono-Add-Plump:
>
>  I've already commented on that a few times.


Yes, and I obliquely responded to your comment. But to be blunt, if 
failure of Mono-add-Plump isn't self-evidently *completely ridiculous* 
(and so much so that anything not compatible with Mono-add-Plump 
compliance is thereby made a complete nonsense of), then I have no idea 
what is.

The only way this view of mine could be dented  (and I made a bit wiser 
and sadder) is if it was proved to me that compliance with 
Mono-add-Plump isn't compatible with some other clearly desirable (IMO)
property or set of  properties.

This doesn't come anywhere near cutting it:

> Your favorite initially won only because of mutual majority support. 
> The plumpers
> declined that mutual support, as is their right. Having declined 
> mutual support,
> should it be surprising or unfair if they no longer have it?

Is it "surprising or unfair" that some new voters should in effect have 
their ballots given negative weight because they refused to play silly 
games with some candidates they weren't interested in and maybe knew 
nothing about? 

Err....*yes*.


> As Jameson said, the chicken dilemma, also called
>  the co-operation/defection problem, or the ABE problem, is
>  the most difficult strategy problem to get rid of.
>
>  However, there are a number of methods that do get rid of it,
>  while complying with FBC and furnishing majority-rule protection:

> You (Chris) proposed one some time
>  ago. Does it meet the criteria that you require, in addition to
>  FBC and avoidance of the co-operation/defection problem?
>  Can it be worded in a brief and simple, and naturally and
>  obviously motivated way, for public propsal?


I've been distracted and thinking about other things. I'll get around to 
addressing those questions, along with my closer look at Forest's MMMPO 
method.

Chris Benham



Mike Ossipoff wrote (15 Dec 2011):

Chris:

 You said that MMT fails Mono-Add-Plump:

 I've already commented on that a few times.


 You said that MMT fails Condorcet's Criterion:

 But, as you know, CC is incompatible with FBC.


 You said that MMT fails Mutual Dominant 3rd:

 I don't know what that criterion is. But, in any case, to
 say that a failure of it is important, you'd have to justify
 the criterion in terms of something of (preferably) practical
 importance.


 You said that MMT fails Minimal Defense:

 Plurality meets Minimal Defense. So my answer will refer to the
 universally-applicable counterpart to Minimal Defense: 1CM.

 Of course MMT fails 1CM. MMT doesn't recognize one-sided coalitions.
 Rather than being an accidental "failure", that is the point of MMT.

 To justify using 1CM against MMT, you'd need to tell why it's
 necessary to recognize one-sided coalitions. You'd need to justify
 it other than in terms of a criterion requiring that recognition.


 You said that MMT fails Later-No-Help:

 With MMT, you can help your favorite by entering into a mutually-chosen,
 mutually-supported, majority coalition. Everyone supporting that coalition
 does so because they consider it beneficial to their interest.

 How is that a "failure"??

 In summary, you're citing those criteria as if their compliance is
 necessary, for its own sake. But when you do that, you need to
 say _why_ their compliance is necessary for its own sake.

For one thing, that depends on what we want. If we choose MMT, we
don't want one-sided support within a majority set of factions to
be counted, when that would mean "You help, you lose".

 Of course you could say that you don't want to avoid the
 cooperation/defection problem, and then tell why.

 As Jameson said, the chicken dilemma, also called
 the co-operation/defection problem, or the ABE problem, is
 the most difficult strategy problem to get rid of.

 However, there are a number of methods that do get rid of it,
 while complying with FBC and furnishing majority-rule protection:

 SODA, and several non-delegating methods:

 MMT, MTAOC, MMPO, MDDTR, and maybe a few others.

 Forest has just proposed one today, and so I haven't yet had
 the opportunity to study it. You (Chris) proposed one some time
 ago. Does it meet the criteria that you require, in addition to
 FBC and avoidance of the co-operation/defection problem?
 Can it be worded in a brief and simple, and naturally and
 obviously motivated way, for public propsal?

 We often cite criteria here. But, to a member of the public who looks
 here to evaluate a method proposed in hir jurisdiction, that will
 be a confusing jumble of mutually-contradictory requirements.

 That's why it's important that we also discuss _why_ we claim that
 a particular criterion is important.

 For instance, I've told why FBC is essential in the U.S.

 And I've told why it's important to avoid the co-operation/defection
 problem.

 Mike Ossipoff