[EM] 3 or more choices - Condorcet

[Kevin Venzke]

Hi Juho,



----- Mail original -----
> De : Juho Laatu <juho4880 at yahoo.co.uk>
>>  Plurality is just a description that is convenient for discussion on the
>>  EM list. "Ranking above last place" isn't a concept that 
> exists (until 
>>  someone feels it would aid their position to bring it up).
>> 
>>  It just takes someone (could be an IRV advocate) to say this many voters 
>>  ranked this candidate first and this candidate second, and didn't rank 
>>  anyone else, etc. If this, without bringing up any criteria, doesn't 
>>  raise an awful lot of eyebrows, then I'm wrong about Plurality. But if 
>>  it does raise eyebrows, then it is up to the pro-margins crowd to explain 
>>  to the public that their mistake is that they believe in "implicit 
> approval"
>>  (without having ever heard of it) and that they should stop, because it
>>  (you will say) encourages harmful strategy.
> 
> Ok, it seems that we are moving in the direction of marketability of the 
> methods.

I was always talking about that as I said it was DOA as a proposal.

> All methods can be attacked based on some of their properties. And in 
> most cases voters are quite unaware of any of those properties, until someone 
> builds such (usually negative) marketing messages and starts using them.
> 
> Sometimes the marketing messages might be based on what actually happened in the 
> election. In Burlington 2009 mayoral elections people were told that IRV failed 
> to elect the Condorcet winner. But it seems that people didn't pay much 
> attention to that failure. Sometimes the marketing stories are based just on 
> "what might happen in theory". It may be that we are talking more 
> about the psychology of the politicians and lobbyists here, and less about the 
> psychology of the actual voters, or the concerns of the election method experts.

I claim the Plurality failure will be relatively easy to depict as
damning since it doesn't need explanation.

Your defense of margins (below) is apparently that the Plurality 
failure is justified because margins makes so much sense. I don't
know how strong that is.

>>  And I want note again that virtually every proposed method satisfies 
>>  Plurality aside from margins and MMPO. So if Plurality is the cause of 
>>  some harmful strategy, your offered alternative must be something really
>>  fantastic.
> 
> I guess Condorcet methods can't ever be successful since they fail such 
> "terrible" criteria as "favourite betrayal" and 
> "burial". ;-) 

That example doesn't make sense. At least the FBC part doesn't.

> I mean that whatever method you want to promote, there 
> are some nasty negative marketing pitches that you must be ready to answer. 
> I'm not sure if Plurality is the most difficult one. One reason is that even 
> experts need to read the definition twice before they properly understand what 
> the idea is and what the implications of the criterion might be.

That's why I said I don't believe the criterion needs to be 
introduced and the failure doesn't need to be explained. Only the 
scenario itself needs to be shown in my opinion.

>>  Ok. In the context of margins' proposability and Plurality I don't 
>>  actually think it matters how people would vote under it. (Though I'm 
> sure
>>  it would come up. Ahaha.)
>> 
>>>  However, even without stategy and property discussions, some voters may 
> be 
>>>  tempted to truncate just because they get the idea (maybe from their 
> traditional 
>>>  voting methods) that marking some candidate on the ballot will give him 
> some 
>>>  "points". But that would be based on lack of understanding 
> and not on 
>>>  the properties on the method in question.
>> 
>>  Right. And when you advocate margins you get the job of convincing 
>>  everybody that they're wrong to think this way. (I do think they think 
>>  this way, and I don't think anyone can change it.)
> 
> Most ranked methods lose a considerable part of their benefits if people 
> generally truncate. In the worst case the behaviour of the methods starts to 
> resemble plurality. It is quite common that the "opposite side" will 
> win, and then one's vote is "wasted" unless one tells which one of 
> the "opposite side" candidates is best. I believe that many enough 
> people will learn not to truncate, to make the results of the election 
> meaningful and fair.

You're writing this an example of what you would say to a skeptical 
public?

> Btw, I think that in some sense margins are easy to advocate. The reason is that 
> there is one simple answer that, if you want, can be used to answer to most 
> attacks against Minmax(margins). The idea is roughly that you thwart all attacks 
> on detais by repeating that the method will elect the candidate who needs least 
> additional votes to beat all others. That is a simple and quite understandable 
> rule that makes sense, not a complex algorithm, and any deviation from that 
> simple rule can be presented as violation of the basic principles of the 
> election. We may thus accept that there are some theoretical cases of burial 
> etc., but we can say that we should still stick to the idea of electing the best 
> candidate as defined by the "least additional votes" rule, since doing 
> otherwise would not elect the best winner (maybe more often). Isn't that a 
> valid marketing approach?

Yes that's an excellent marketing approach. I think advocates of *all*
methods should try to boil down the rationale to a single sentence.

I don't think it is a decisive argument though. Many things in the 
world sound good in overview but end up having problems that weren't
obvious from the definition.

>>>  I think the correct message to voters 
>>>  in most ranked method based elections is to encourage them not to 
> truncate but 
>>>  rank all ralevant (good and less good) candidates sincerely.
>> 
>>  I actually don't understand the meaning of this kind of statement. Who 
>>  is in the position of sending messages to voters? I think the political 
>>  players will tell their supporters whatever they think is most 
> advantageous,
>>  and no one will consult the EM list.
> 
> Maybe the question of truncation will pop up in various places. I wonder who 
> would give a general advice "yes, trunction is what you should do". 
> That doesn't make much sense. I guess it would be more popular to say 
> "you can rank the candidates in the new method, so be thankful about that 
> and rank them".
> 
> It is probably easier for the politicians to say "at least I will not even 
> rank their candidates". That is a message saying that this party/wing is so 
> bad that I don't even want to touch them. But I guess people are used to 
> hearing this kind of negative talk from the politicians. They might react by 
> ignoring such recommendations, or alternatively the polarization would raise to 
> the levels of plurality style voting between the two major wings. I hope and 
> guess that the first approach will become more popular in time.

The reason I would tell voters to truncate (or in margins' case, bury**)
is that there is generally only risk and no possible gain to ranking the
worst viable candidate over unviable inferior candidates. It is a 
practical thing, not a way to overstate political sentiments.

** - If margins elections prove to be ruined by burial then I won't 
recommend burial.

Kevin