[EM] My summary of the recent discussion

[Juho Laatu]

On 3.6.2012, at 22.52, Jameson Quinn wrote:

> 2012/6/2 Juho Laatu <juho4880 at yahoo.co.uk>
> On 2.6.2012, at 18.19, Jameson Quinn wrote:
> 
>> 
>> 2) Approval method and its strategies were once more discussed. My understanding is simply that Approval works quite fine as long as there are only one or two winnable candidates, but when there are three or more, the method pretty much fails
>> 
>> Fails compared to what? At its worst, approval is still better than plurality; and depending on your voting model, it could be much better (for instance, honest probabilistic approval is range, with great BR).

> I was just thinking that it "fails to work properly".
> 
> Approval is more expressive than Plurality and it allows (small) third parties to run without becoming spoilers. But I wouldn't say that it is categorically better than Plurality since there are many needs and many uses for election methods. One difference is that Approval is a compromise oriented method while Plurality aims at electing from (and forming) large parties. If our target is to establish a two-party system, Plurality is our natural choice.
> 
> I strongly disagree. Even for a two-party system, plurality's flaws are worse than its advantages. Even if two-party is your goal (and I'd argue that's a bad goal, you can get the same actual beneficial ends without two parties if you need to), IRV and/or official party primaries are the way to get it.

Problems of Plurality:
- votes to third parties are pretty much lost votes
- voting becomes very problematic when there are more than two potential winners

Problems of Approval:
- voters must find their best strategic vote (in competitive elections)
- voting becomes very problematic when there are more than two potential winners

Differences
- Plurality elects from large parties
- Approval elects compromise candidates (strategies may lead to something else too)

Based on this ultra-quick analysis, all depends on what the targets are.

I think Plurality can be claimed to be the ideal method for the single-member districts of a two-party system, but then one should maybe also think that third parties should not be allowed to run, and we should stick to the same two parties forever. That would be a very pure two-party system. I guess you want a system where third parties are allowed and they should also have some more important role in the system than just be a channel for protest votes.

Let's then assume that we are interested in using an existing two-party oriented political system otherwise as it is, but replace Plurality with some other single-winner method in the single-member districts when we elect a representative body. Obviously we are also interested in allowing third parties to get seats. Plurality is out of question.

A) With compromise seeking single-winner methods like Approval and Condorcet the size of the party is not very important. Small centrist parties/candidates may get lots of seats (more than it would get in proportional elections).

B) With large party oriented single-winner methods like IRV (and others) the system stays closer to what it was. Higher number of representatives would come from large parties, but the new method would allow new parties to rise and replace the old large parties.

I wrote this last part just to point out that the choice of the method will have a considerable impact on the dynamics of the system. Again we should agree first on what the targets are and only then say which methods are the best for our needs.

Juho




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