[Election-Methods] A Better Version of IRV?

[Juho]

On Jul 12, 2008, at 17:56 , Kristofer Munsterhjelm wrote:

> Dave Ketchum wrote:
>> Again, why NOT Condorcet?
>> Its' ballot is ranking, essentially the same as IRV, except the  
>> directions better be more intelligent:
>>      Rank as many as you choose - ranking all is acceptable IF you  
>> choose.
>>      Rank as few as you choose - bullet voting is acceptable if  
>> that completes a voter's desired expression.
>>      Equal ranking permitted.
>> Condorcet usually awards the same winner as IRV.  Major differences:
>>      Condorcet looks at ALL that the voters rank, while IRV  
>> ignores parts.
>>      Condorcet recognizes near ties, and tries to respond  
>> accordingly.
>> Could be a debate about the near ties - would it be better to  
>> resolve such with a runoff?  Runoffs take time and are expensive.   
>> Are they enough better than what Condorcet can do with the  
>> original vote counts?
>
> On technical merit alone, why not Condorcet indeed? But the thread  
> was about momentum. In the situation where IRV can't be stopped,  
> what is the best way to nudge IRV towards something more desirable  
> while still keeping it IRV-ish enough that it'll retain the  
> momentum of "pure IRV"?

One very simple approach would be to promote ranked methods as one  
group. Just join the bandwagon, include all methods and leave the  
details of the method to be decided later (pick the best then). The  
delta from plurality to ranked methods and achieved improvements are  
clear.

>
> One modification that's been mentioned before is bottom two runoff  
> - eliminate the one of the two last placed that fewer prefer to the  
> other. That would ensure a Condorcet winner always wins, but to  
> core IRV supporters, that's a weakness, because the Condorcet  
> winner could be a weak centrist. The ameliorated procedure would  
> also fail LNHarm.
>
> If the people on which the momentum is based would support any sort  
> of elimination procedure, then I think Borda-elimination would be  
> better; so what one really has to ask is, if IRV is unstoppable,  
> then how far from pure IRV can you go and still have it be IRV? IRV  
> with candidate withdrawal? IRV with candidate completion? BTR-IRV?  
> Schwartz,IRV? Any sort of elimination system? Any sort of ranked  
> ballot system?
>
>
> One argument against Condorcet, which one may call half-technical,  
> is complexity. It's technical because it regards the method itself  
> and not whether Condorcet Winners are good winners (or similar),  
> and nontechnical because what's complex to a computer may not be  
> complex to a person and vice versa.
>
> As far as complexity with regards to Condorcet goes, the good  
> Condorcet methods are complex. Schulze may be easy to program (once  
> you know the beatpath algorithm), but explaining beatpaths to the  
> average voter is going to be hard. Copeland is easy but not very  
> good and ties a lot.

Some Condorcet methods are simple, like minmax. It is good too. I  
note that you later referred to cloneproof methods as good methods.  
Minmax is not fully cloneproof but I don't think that is a problem.  
(Same with not being fully Condorcet loser compliant.)

If your favourite Condorcet method is complex then it may better  
start with promoting Condorcet methods in general. I think it is in  
any case a mistake to dive into the details of the methods when  
promoting an electoral reform. Citizens and politicians are simply  
not interested in such dives (would be counterproductive). Better to  
use some more general arguments that are linked to the reform needs  
at more general level.

>
> One thing I've observed is that IRV focuses on how the process is  
> done, while Condorcet methods focus on properties ("the winner is  
> the candidate which wins all one-on-one contests"). I'd say  
> explaining properties would be more easily understood than  
> explaining the process, but apparently this isn't a great  
> limitation for IRV, given its momentum so far.

IRV is typically described as it it was a "public fight" between  
candidates where the candidates are eliminated one at a time. This is  
a very appealing style because of the very real life like and exiting  
image it offers. The description also sounds quite fair (at least at  
first sight).

There are also differences in how different Condorcet methods are  
described. To me methods that are justified using (possibly long)  
beat paths are philosophically different from methods that are based  
on evaluating the more local properties of individual candidates  
(e.g. minmax).

(Also the philosophy of finding a complete ordering of the candidates  
is different from the philosophy of just identifying the best  
candidate without establishing a complete order. The interesting  
point is that individual preferences of the voters are usually  
expected to linear while it is known that group opinions may well be  
cyclic (just a natural property, not a fault that should be somehow  
corrected).)

>
> Perhaps Ranked Pairs would have a chance? It's one of the better  
> Condorcet methods (cloneproof, etc), and if people accept the  
> pairwise comparison idea, it should follow quite easily. Say  
> something like that you can't please everyone all the time, so  
> please most, which is to say that one locks preferences in the  
> order of greatest victories first. Then anyone complaining because  
> his group's (cyclic) preference was not locked could be rebutted by  
> a larger group saying that if it had been, more people (namely,  
> that larger group) would have been overridden. Here you have both  
> method (locking) and properties (group complaint "immunity"), as well.
>
> It'd be interesting to investigate which simple or intuitive  
> methods are the best. I don't know what would constitute simple to  
> voters, perhaps "Of those candidates that [some statement], choose  
> the one that [some statement]", or "[Somehow reduce the set of  
> candidates] until [criterion is met], then that one is the winner"  
> for various sentence parts inside the brackets. Those are all  
> method-based explanations; maybe property-based ones would be  
> better. If the voter trusts that the method does what the property  
> says, and the property is desirable, then that could be the case.

I'll continue my "minmax campaign" a bit more. The best part of minmax 
(margins) (and the reason why I'm interested in it) is that it has a  
very natural (and easy to understand) description and justification.  
It elects the candidate that needs the least number of additional  
votes (if any) to win each of the other candidates (in pairwise  
comparisons). I'd say that is a reasonably good description of a  
candidate that deserves to win (if one is looking for a good  
compromise candidate).

Juho


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