[EM] Strategy-free criterion

[Chris Benham]

Kevin,

>   "Does that mean that you find  failure of Mono-add-Plump acceptable?"
> Compared to Plurality criterion failures, sure.

No, that is very very weird and wrong.  A failure of Mono-add-Plump is 
completely absurd and outrageous and a failure destroys the credibility 
of the winner, whereas a failure of the Plurality criterion is merely 
very embarrassing and hard to sell.

Also giving away Plurality can "buy" something sort-of worth having. For 
example MinMax Margins is not an absurd method and has a "maximal set" 
of Woodall properties.  It fails Plurality but meets Condorcet and I 
think Mono-add-Top and Later-no-Harm.

But I refuse to believe that we need to give up Mono-add-Plump (or 
Mono-append) compliance to get anything remotely worth having. (And if 
I'm wrong about that I wouldn't accept the bargain.)

> Something I will have to post about at some point is what a 
> game-changer it is if we
> take it as an assumption that elections will have two frontrunners and 
> all voters
> use frontrunner truncation strategy. Arbitrary-looking majority rules 
> prove very
> useful in maximizing performance.
>
> In such a setting I find that MAMPO is usually not as good as MDDA or 
> RMPA, but all
> of them outperform all Condorcet methods at sincere Condorcet efficiency.

A near-universal assumption among Condorcetists is that if (assuming the 
voters are free to rank enough candidates) there is a voted CW then that 
must be the sincere CW and everything is perfect.

You imply that your aim is to elect the "sincere CW" (if there is one).  
I think we should be trying to elect a candidate with no lower Social 
Utility than the highest SU voted Smith set member.

The person who coined SFC (and supports MD) also coined the Chicken 
Dilemma criterion, which is directly incompatible with MD.

https://electowiki.org/wiki/Chicken_dilemma

I am in sympathy with both criteria so one of my standards is that a 
rankings-only method must meet one or the other.

Chris B.

On 11/06/2024 9:30 pm, Kevin Venzke wrote:
> Hi Chris,
>
>> Kevin,
>>   
>>> Who in 49/24/27 ranks a candidate below the less-liked frontrunner?
>> No-one, which is why any method that meets SD and Plurality  must elect B.
>>   
>>> MD basically says that if there are two frontrunners and everyone truncates
>>> their
>>> less liked frontrunner, then the worse frontrunner won't win.
>> "Truncates"  X means vote no-one below X.
> In that case I mean "truncate above X but below the other frontrunner."
>
>>> If this property doesn't hold, it means the majority has done something to stop
>>> the method from
>>> "seeing" their majority, which is surely that they ranked other candidates above
>>> the preferred frontrunner.
>>   
>> But here you talk about "ranked other candidates above" which has
>> nothing to do with truncation.
> Truncation is what MD requires for it to work, but the problem it's usually
> addressing is compromise. Every method that violates MD in 49/24/27 violates it
> because of C being ranked above B. Betray C and there is no more issue. That's
> bad, and MD wants to offer a way to fix it.
>
> If MD fails to work because voters fail to truncate, that's not a violation of MD.
>
>> That sounds more like failure of Non-Drastic Defense (which says that if
>> more than half the voters vote X above Y and X no lower than equal-top
>> then Y can't win.)
> NDD is a weaker form of MD that does less to counter compromise.
>
>>> In such a setting I find that MAMPO is usually not as good as MDDA or RMPA, but
>>> all of them outperform all Condorcet methods at sincere Condorcet efficiency.
>>   
>> That's great.  Does that mean that you find  failure of Mono-add-Plump acceptable?
> Compared to Plurality criterion failures, sure.
>
> I don't really want to prejudge methods based on criteria that might primarily be
> important for marketability reasons. I say "primarily" not "purely."
>
> Hypothetically if there were a movement promoting MDDA, and in this world MDDA
> doesn't violate the Plurality criterion, then Mono-add-plump failures wouldn't stop
> me from supporting that movement.
>
> And really, if I found that the whole world was actually OK with Plurality
> failures, I might relax my stance on that as well. Because the marketability aspect
> of Plurality failures is a big part of my allergy to them. Maybe I would study
> under what conditions MDDA would have high risk of violating Plurality, and see if
> I could live with it.
>
> Kevin
> votingmethods.net
>