[EM] MAS defined.

Juho Laatu juho.laatu at gmail.com
Tue Oct 11 03:22:32 PDT 2016

```I reread the Chicken Dilemma Criterion article in the spirit of "of course B should win". To me the weak point in the article seemed to be the sentence "The B voters refuse to vote A over anyone". The description did not clearly express the underlying assumption that A and B candidates and voters actually are very close to each others (similar minded). A voters sincerely like B much more than C, and B voters sincerely like A much more than C. A and B voters together have majority over the C voters, and therefore one of them ("the AB team") should win. Because A is more popular than B, A should win. But B voters are strategical and therefore "refuse" to vote sincerely, and decide not to rank A above C. In a good election method this strategy should preferably not work. There is a risk that both A and B voters "refuse" to support B and A respectively (not rank them second as they should), and as a result their worst alternative (C) could win.

Did this explanation make the philosophy of the "chicken style" criteria clearer?

B should not win since if B would win by using this strategy, that could encourage also A supporters to do the same, and the whole election could become a mess where the winner would be quite random (depending on how many voters of each group voted strategically). Note that the number of A and B voters could be about the same, and A and B voters would not know which group would benefit of applying the "refusal" strategy.

Juho

> On 11 Oct 2016, at 09:00, Brian Kelly <bkelly1984 at gmail.com> wrote:
>
> Hi Jameson,
>
> It's always good to see people thinking on these problems and trying
> to come up with solutions.
>
>> MAS is good at dealing with a vote-splitting situation ("chicken dilemma"...
>
> I've not heard of the Chicken Dilemma before and found a definition at
> http://wiki.electorama.com/wiki/Chicken_Dilemma_Criterion.  Now I'm
> more confused because in my opinion, candidate B should win the
> election described.
>
> It is looking to me like the Chicken Dilemma is just a test to see if
> a voting system is susceptible to bullet voting.  In that case, every
> system except plurality fails this criteria.
>
> Am I missing something?
>
> On Mon, Oct 10, 2016 at 10:24 PM,
> <election-methods-owner at lists.electorama.com> wrote:
>> Only subscribers are allowed to post to this mailing list.  Please
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>>
>> ---------- Forwarded message ----------
>> From: Brian Kelly <bkelly1984 at gmail.com>
>> To: The Center for Election Science <electionscience at googlegroups.com>
>> Cc: election-methods at lists.electorama.com
>> Date: Mon, 10 Oct 2016 21:24:05 -0700 (PDT)
>> Subject: Re: MAS defined.
>> Hi Jameson,
>>
>> It's always good to see people thinking on these problems and trying to come up with solutions.
>>
>>> MAS is good at dealing with a vote-splitting situation ("chicken dilemma"...
>>
>> I've not heard of the Chicken Dilemma before and found a definition at http://wiki.electorama.com/wiki/Chicken_Dilemma_Criterion.  Now I'm more confused because in my opinion, candidate B should win the election described.
>>
>> It is looking to me like the Chicken Dilemma is just a test to see if a voting system is susceptible to bullet voting.  In that case, every system except plurality fails this criteria.
>>
>> Am I missing something?
>>
>>
>>
>> On Thursday, October 6, 2016 at 12:41:41 PM UTC-6, Jameson Quinn wrote:
>>>
>>> I've been working on a simple three-slot system as a next step after approval. This has gone through various iterations and names: U/P, MUMA, NUMA. The latest, and I hope final, version is MAS, Majority Acceptable Score. Here's an explanation, intended for those without a voting theory background. The basic system is described in 3 sentences in the first paragraph; the second paragraph describes the default rule, which is worthwhile but not absolutely essential to the system; and the next two paragraphs give some scenarios.
>>>
>>> For each candidate, you may upvote, “midvote”, or downvote. Candidates with a majority of downvotes are eliminated, unless that eliminates everyone. The remaining candidates get 2 points for every upvote and 1 for every midvote. Most points wins.
>>>
>>> When people leave a candidate blank, that could mean one of two things: “never heard of this person”, which should count as a downvote for safety; or “no strong feelings”, which should count as a midvote (because if the voter really disliked the candidate they would have downvoted). To distinguish these possibilities, see if the candidate’s score from non-blank votes averages at least half a point per voter; for instance, this would be true if they were upvoted by 25%, or explicitly midvoted by 50%. If the score is this good, that candidate is reasonably well-known and well-liked, so blanks count as midvotes; if it isn’t, that candidate is relatively unknown, so blanks count as downvotes.
>>>
>>> MAS is good at dealing with a vote-splitting situation ("chicken dilemma", so called because in many voting systems it can work like a game of chicken between the two majority subfactions). Say that one "side" of voters have 55%, but there are two candidates on that side splitting the vote and only one on the other side. In this case, assuming voters on either side downvote the candidates on the other side, the 45% candidate will be eliminated by downvotes, and whichever subfaction of the majority has more supporters will win.
>>>
>>> MAS also deals well with a "center squeeze" scenario, in which a centrist candidate faces off against candidates on either side. Assuming all three are equally qualified and likeable, the centrist will probably be able to beat either side in a one-on-one race (because leftist voters will prefer Center over Right, and vice versa); but it is quite possible that there will be more partisans on either side than in the center. In this case, the centrist should not be punished simply for being more "crowded" ideologically; their ability to dominate one-on-one means they should win. But many voting systems, such as IRV, can eliminate the centrist prematurely, giving results like the tragic outcome in Egypt 2012. Meanwhile, other systems, such as Condorcet, can enable tricky strategies by one side to possibly win. In MAS, as long as the center candidate was preferred by a respectable number of voters (say, 20% or more), "midvotes" from voters in either wing would probably be enough to let the centrist win; and either defensive "midvoting" from the weaker wing or defensive "downvoting" by the centrists would probably be enough to stop a takeover by the stronger wing.
>>
>>
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