[EM] IRV's adequacy depends on a two-party system

[Juho Laatu]

IRV has some strong links to the two-party system. That is also one key reason why it is seems to be the most popular approach to reform in the USA.

Jameson Quinn talked about two-party dominance and two-party duopoly, and here we have terms two-party and centre-squeeze. We have also seen terms like "weak Condorcet winner". These are all related in a way that I intend to discuss below.

In addition to the centre-squeeze property, IRV has also an edge-squeeze property. I mean that in the word pair "centre" and "squeeze", the "squeeze" part is actually the dominant part. Any squeezed candidate (with low first preference support) is likely to be eliminated soon in the IRV elimination process.

My message is that instead of having all these terms, maybe one natural approach would be to classify IRV and few of its kind as a separate subcategory of methods. What separates (from this point of view) IRV and plurality from Approval and Condorcet is their tendency to avoid electing minor centrist compromise candidates. That can be seen as an intentional property, not just as a failure. In some recent discussions there have been also some other methods whose aim is to maintain the two-party dominance (duopoly in Jameson Quinn's terms), but still allow third parties to run without becoming spoilers. This category of methods could be called two-party methods (or duopoly methods).

The philosophy of such methods is to elect "strong" candidates, where "strong" means that these candidates will have typically more than or close to 50% support, and they have more (first preference) support than any other alternative candidate. This approach has the tendency to lead dominance of two major parties.

Within this group of methods we might set additional requirements like being able to allow also third parties/candidates to compete and one day replace one of the two dominant ones. In this set-up we may propose better alternatives to (from this point of view) bad two-party methods like plurality (that is quite terrible with third parties), but without going all the way to the compromise seeking single-winner methods like Approval and Condorcet.

Note that if there will be a reform in the USA, the end result could be quite different if the chosen new method is still a two-party method or if it is a compromise seeking single-winner method. Both reform types allow third parties to compete and become elected one day, but two-party methods would still have the tendency to maintain the dominance of two parties (or at least two or three major parties with chances to win in each single winner district).

A compromise seeking method could elect multiple compromise candidates from small groupings in the representative bodies, and as a president too. This would mean that the president would quite typically not have majority support in the representative bodies. And that would lead to somewhat different behaviour of the whole system, when compared to what it is today. Already single-winner reforms may thus be classified in this way in two categories - those that aim at duopoly or "tripoly" (=major representatives) and those that aim at a richer mixture of single-seat winners (=major and compromise representatives).

Already the two-party method based reforms could lead to meaningful changes by allowing new parties (major party of some district) to enter the representative bodies. That could mean that new governments could be coalition governments (e.g. Democrat + Progressive) instead of the single-party governments of today.

Based on this discussion, possible reforms could be classified at least in three categories: two-party reforms, more general/liberal single-winner reforms, and proportional representation based reforms (in the order of radicalness). The title of this mail stream would mean that IRV belongs in the first category of reforms.

Juho




On 3.12.2011, at 6.49, Brian Olson wrote:

> Just the subject line on this is the most amusing thing I've read on this list in a while.
> Well said, sir!
> 
> On Dec 2, 2011, at 2:19 PM, MIKE OSSIPOFF wrote:
> 
>> 
>> David Wetzel said:
>> 
>> s for center-squeezing, that's not really a problem in the US as a
>> whole...
>> Third parties are too small and scattered.
>> 
>> [endquote]
>> 
>> Ok, so David is saying that IRV is adequate adequate only in a two-party system.
>> 
>> Mike Ossipoff
> ----
> Election-Methods mailing list - see http://electorama.com/em for list info

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.electorama.com/pipermail/election-methods-electorama.com/attachments/20111203/ab26cc96/attachment-0003.htm>