[Election-Methods] USING Condorcet

[Juho]

Some additional points that I missed in my previous mail.

- The second preferences of A supporters are important. B should  
maybe be friendly towards A. A strategic plan targeted against A  
would lead to some sincere A>B supporters becoming sincere A>C  
supporters.

- The second preferences of C supporters are important. B should  
maybe be friendly towards C. C supporters are in a position where  
they can decide who is the winner (neither A nor B has majority of  
the votes, but C voters can make either of them win).

- The strategists have probably do not have any complete list of  
ballots available (might have too if they have good relations to the  
poll organizer). Making strategic decisions based on the pairwise  
matrix or even smaller amount of information (e.g. the order of the  
candidates) is not as easy as when knowing the opinions of each  
individual voter. (Note also that the sample size in the poll should  
be larger than in a typical plurality poll to get reliable  
information on the number of voters with some particular voting  
pattern (e.g. A>B>C).)

- One form of defence against the strategists is not to give any  
information in the polls or to give false information (random or  
planned) to fool the strategists. If some strategic voting will take  
place in these elections it is possible that in the next elections  
people/parties would defend themselves this way. This may be more  
efficient than e.g. counter strategies in the actual election.  
Hopefully the end result of all this would be that all parties would  
recommend sincere voting. That is a good main rule for Condorcet  
elections anyway.

- It is also possible to intentionally publish false polls.


One way to demonstrate that Condorcet indeed would be vulnerable to  
strategic attacks in real life elections (large, public, with  
independent individual opinion formation) would be to present a  
plausible real life example situation (e.g. in the form of some poll  
results) and then design a strategic recommendation that B party (or  
its supporters, or media) could distribute via the media to its  
potential supporters. Then one could calculate some possible  
scenarios with varying changes in the opinions of the voters (natural  
shift, reactions to strategic plans, false polls) and varying levels  
of strategic voting (including counter strategies and other  
strategies) among the voters.

Juho


On Jul 2, 2008, at 8:51 , Juho wrote:

> Ok, election with three candidates only is the most risky from  
> burial point of view since then it is easy to identify the relative  
> position of different candidates (one winner (A), one loser but  
> powerful enough to try the strategy (B), one loser that is weak  
> enough to be used for burial (C)).
>
> My point is that in real life large public elections strategies are  
> much more difficult to implement than in theoretical examples on  
> paper. I'll list some points that indicate why burial is not very  
> likely to happen or be successful.
>
> - In most cases the set-up is not as clear as in the theoretical  
> burial examples. There may be more than three candidates. The  
> relative position of the candidates may be unclear.
>
> - Use of the burial strategy indicates that the runner-up thinks he  
> will lose. In a situation where there are two leading candidates of  
> same strength burial would not make sense since the strategy can  
> not be kept secret and supporters of both candidates would use it,  
> and that would just elect C. I think I have actually never seen a  
> runner up candidate that would indicate before the election that he  
> will lose to the other main candidate (and therefore wants his  
> supporters resort to strategic voting).
>
> - A positive campaign for one's own candidate (and potentially  
> negative against the competitors) is thus the typical case. Often  
> even the C candidate presents himself as a potential winner all the  
> way until the election day.
>
> - If B is so far from victory that all his supporters may safely  
> give up hope of winning the election and turn to the strategic plan  
> he may already have too little supporters to run the strategy  
> successfully.
>
> - The available polls are inaccurate.
>
> - The opinions are likely to change before the election (when  
> compared to the available polls).
>
> - The strategic candidate may lose votes due to the plot (depends a  
> bit on the society and if it approves or disapproves the  
> strategists). The campaigns of A and C will probably take maximal  
> benefit of B's bad morale and B's tendency to give up the hope of  
> victory already before the election.
>
> - The leading candidate may gain extra votes since he is declared  
> to be the leading candidate before the election. On the other hand  
> elections are surprisingly often close to 50-50 at the election day  
> (which would make the strategy again unwise).
>
> - It is not possible to control the voting behaviour of thousands  
> or millions of voters.
>
> - It is possible that if too many B supporters will follow the  
> strategy C will win. It is impossible to control the number of  
> strategic voters when this risk exists.
>
> - Many voters probably will not understand the strategy or are not  
> listening and therefore will not follow it.
>
> - Also some A and C supporters may follow the strategy.
>
> - Many B voters may not use such strategy since they feel it is not  
> right (also this may depends on if the society approves or  
> disapproves the strategists).
>
> - Many B supporters certainly believe that B will win (this kind of  
> optimism is common and also strategically wise). It is not within  
> their interest to declare B as a loser and resort to strategic  
> voting and a corresponding campaign.
>
> - The election is likely to contain all kind of votes. In the case  
> of three candidates that means A>B, A>C, A, B>A, B>C, B, C>A, C>B,  
> C, A=B, A=C, B=C. The preference strengths are also different, e.g.  
> A>>B>C vs. A>B>>C. And the voters may have different rationale and  
> morale. All this makes the system less easy to manage than in the  
> clean cut theoretical examples.
>
> - For many voters the risk of backfiring may be a reason not to use  
> the strategy (the actual strength of C is unknown, possible use of  
> strategy by the A supporters is unknown etc.).
>
> I'll skip writing a concrete example this time since there is  
> already plenty of text here. A detailed analysis with the numbers  
> is complex due to the numerous uncertainties that I listed above.
>
> Juho
>
>
>
> On Jul 1, 2008, at 22:19 , Kevin Venzke wrote:
>
>> Hi Juho,
>>
>> --- En date de : Mar 1.7.08, Juho <juho4880 at yahoo.co.uk> a écrit :
>>> De: Juho <juho4880 at yahoo.co.uk>
>>>> I don't entirely agree. I would rank below my
>>> strategically-determined
>>>> approval cutoff (if I suppose the same election could
>>> be held also
>>>> under
>>>> Approval), but I wouldn't rank that much lower,
>>> and I don't think
>>>> other
>>>> voters should either.
>>>>
>>>> Two reasons for this.
>>>>
>>>> 1. If you rank everybody and are predictably sincere,
>>> burial strategy
>>>> by other voters is more likely to succeed against you.
>>> People who
>>>> would
>>>> use this strategy need to have doubt about what
>>> you're going to do.
>>>> Truncating at the (strategically determined) approval
>>> cutoff is
>>>> good at
>>>> this: The main effect is that voters don't rank
>>> all the frontrunners,
>>>> and burial strategy works basically by assuming one
>>> frontrunner will
>>>> get support from another.
>>>
>>> Also heavy truncation is dangerous since that could lead
>>> even to
>>> extensive bullet style voting (and all the benefits of
>>> Condorcet
>>> would be lost).
>>
>> I don't suggest truncating any higher than the approval cutoff. It  
>> should
>> be safe to truncate somewhat lower than that.
>>
>> Anyway, whether truncation is a danger to the quality of the  
>> results of
>> the method is quite a different question from whether truncation is a
>> danger to a specific voter. I think a voter would hardly ever be  
>> harmed
>> by truncating where I suggest (you're withholding support from  
>> options
>> that you shouldn't need unless your information is bad), while  
>> they help
>> (over time) to create a deterrent to burial.
>>
>>> I also think that the probability of successful strategic
>>> voting in
>>> large public elections is very small in Condorcet.
>>
>> It doesn't have to be successful. Backfiring strategy is a problem  
>> too. A
>> given voter simply being able to imagine how the strategy could  
>> work is a
>> problem.
>>
>> If everyone is giving full rankings I think the latter is too  
>> easy. Don't
>> worry about the Wikipedia election, just take a simple scenario  
>> with two
>> frontrunners and a third, weak, undesirable niche candidate. If I  
>> think
>> everyone will give full rankings, then the only reason for me to  
>> not use
>> burial against the worse frontrunner is the possibility that his
>> supporters will be using this strategy against my candidate.
>>
>> I should not be able to contemplate such a strategy just because  
>> of the
>> presence of a third, unviable candidate!
>>
>> In such a scenario, ranking all the alternatives would and should
>> accomplish nothing (unless you support the third candidate). The only
>> reason to ask these voters to do that is that it would be nice if  
>> we could
>> say it worked. As strategy advice in this scenario I think it is  
>> poor.
>>
>> Kevin Venzke
>>
>>
>>
>>        
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