[Election-Methods] USING Condorcet

[Juho]

On Jul 6, 2008, at 5:48 , Kevin Venzke wrote:

> Hi Juho,
>
> --- En date de : Jeu 3.7.08, Juho <juho4880 at yahoo.co.uk> a écrit :
>> That scenario was the simplest I could imagine. Only three
>> candidates. One strong candidate but below majority, one
>> weaker
>> runner-up, and third clearly weaker candidate. This was
>> also the most
>> threatening scenario from burial point of view that I could
>> imagine.
>> Are there simpler and more threatening ones?
>
> Again, it isn't enough to isolate the scenario where the strategy
> succeeds. What matters is the scenario where the strategy is worth
> attempting.

Aren't we looking for scenarios where the strategy succeeds and are  
therefore worth attempting? (except if fearing that the voters would  
use some irrational strategies)

> It is no consolation that the strategy does nothing when
> the strategizers' candidate is the CW (due to a majority or due to
> second preferences from the third candidate's supporters), or when  
> creating a cycle doesn't change the winner.

Yes, no incentives here.

> The strategy has to hurt their own interests. Call the major  
> candidates
> A and B, with the third candidate being C. A voters will use burial
> strategy. Why would they not?
> 1. Because it could move the win from A to B: Impossible because this
> would violate monotonicity.
> 2. Because it could elect C: Only when the B voters use burial  
> strategy
> themselves. (We're assuming everyone will give full rankings of  
> course.)
>
> Even though the strategy may hardly ever *work*, it's quite  
> unlikely that
> it will hurt to try it, unless the opposing voters are using it too.

Ok, but there must be a reason why the A supporters would use the  
strategy and the B supporters would not.

> Compare with an IRV voter who uses burial because it feels right  
> and isn't
> expected to make any difference.

IRV has quite different strategic incentives. Also irrational  
strategies are a potential area of study (although not the default  
case).

> I don't think you have to be a thief,
> or even trying to deter thieves, to use this strategy.
>
> By the way:
> C is a minor candidate who makes it onto the ballot without anybody
> knowing much about him except his few supporters.

Yes, I guess we must pretty much assume so to make the strategy work.  
Of course if there are only three candidates then also C is known by  
all the voters although it may be clear that with sincere votes C has  
practically no chances to win.

> I guess you don't have
> candidates like C in your country, since you always seem to speculate
> about how many second preferences he would be getting in a real  
> election.

I think I was at least in most places referring to second positions  
in the sincere preferences and the impact of that with respect to the  
strategic incentives that the voters have.

> Maybe Condorcet would encourage a better candidate than C to enter the
> race (call him "D") but it's not clear that Condorcet would make C go
> away or that there always would be a D candidate.
>
> Even if A and B voters "sincerely" give C a second preference,  
> essentially
> ranking the unknown option above the competition, I consider it hardly
> any different from using burial strategy, in terms of its destructive
> effect on the outcome.

Ok, any scenario with or without Condorcet winners will do. All we  
need to show is that there are scenarios that are plausible in real  
life (large public elections) and where use of burial strategy is  
likely and successful (does more good than harm). Do you have some  
specific set of votes in your mind that we could analyse?

(I may have leaned in some direction in my comments but the idea is  
really to just identify one or more concrete cases (anticipated  
opinions / poll results and strategy recommendations to the voters)  
where the burial strategy would indeed work.)

Juho


>
> Kevin Venzke
>
>
>        
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