[EM] IRV vs Condorcet vs Range/Score

[Dave Ketchum]

On Wed, 15 Oct 2008 18:49:41 +0200 Kristofer Munsterhjelm wrote:
> Raph Frank wrote:
> 
>> On 10/9/08, Dave Ketchum <davek at clarityconnect.com> wrote:
>>
>>>      If there is a near tie among three or more, they often disagree but
>>> usually get one of the leaders - matters little since the leaders 
>>> were about
>>> equally deserving.
>>
>>
>> It matters because IRV reinforces the 2 party system.
>>
>> it would be interesting to know what would be the effect of electing a
>> parliament by condorcet voting from single seat districts.  It is
>> possible that it would also result in a 2 party system.
> 
> 
> Since Condorcet is a majoritarian method (as it needs to be in order to 
> be a good single-winner method), the resulting parliament would also be 
> majoritarian. This means that a party whose candidates consistently got 
> low support in all districts would find none of those elected.
> 
> But Condorcet is also a better single-winner method than Plurality, so 
> the candidates would be better representatives of the majority. They 
> would probably be good compromise candidates, so the parliament would be 
> less party-based than one elected by PR methods.
> 
> This might not be all that good for traditional parliaments; I don't 
> know if the majoritarian nature would lessen competition (except in 
> dominant-party states, where using Condorcet would be an improvement on 
> Plurality in that respect), but it would reduce the voice of the minority.

I claim the arguments here as to 2 party domination are overdone - and 
sometimes in a way to inspire undesirable resistance by those parties.  I 
would rather emphasize the positive aspects:

With Condorcet EVERY voter can vote preference between the two major 
parties, no matter what the voter's primary interest may be.

With Condorcet EVERY voter can also express whatever interest may be felt 
as to other candidates.

Note that these abilities do not conflict, though voters can emphasize 
whichever they choose as most important to them.

With Condorcet's N*N arrays all candidates and their backers have a 
recording of voter interests and can and should adjust based on what they 
can learn of voter desires from the N*N reports as to pairs of candidates.
> 
> It might be a good choice for an upper house decided to be a moderating 
> counterweight to a populist lower house.
> 
>> However, based on certain assumptions, IRV is 2 party reinforcing.
>> Also, Australia gives "experimental" evidence that IRV leads to a 2
>> party system.

How much of that is due to election method, and how much as to other 
aspects of politics and elections?
>>
>> Condorcet wouldn't necessarily, so that is a good reason to at least 
>> try it.
> 
> 
> It's possible that IRV is a bad single-winner method precisely because 
> STV is a good PR method (with many seats). In STV, one doesn't need to 
> find a candidate that covers a large area of opinion space, since other 
> candidates can be used to cover those areas, but in IRV there are no 
> other positions to be used in such a manner. I'm not sure if this is the 
> reason, but it would fit well with my simulation results that 
> "majoritarian IRV" (eliminate until only k remains for council size k) 
> is a surprisingly good PR method, at least in absence of strategy.
> 
Of course simulations can help but, too often, they are affected by biases 
of the simulator.
-- 
  davek at clarityconnect.com    people.clarityconnect.com/webpages3/davek
  Dave Ketchum   108 Halstead Ave, Owego, NY  13827-1708   607-687-5026
            Do to no one what you would not want done to you.
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