[EM] Strategic polls in Approval

[Juho]

On Jan 8, 2007, at 6:23 , Abd ul-Rahman Lomax wrote:

> I find it odd that IRV proponents would claim that IRV can save  
> money by eliminating the need for primaries

I just note that in principle primaries are different from the actual  
election in the sense that in typical primaries the  
_party_supporters_ elect their candidate for the actual race. This  
means that you will get an "average" compromise candidate from the  
party. In the US the difference could be that in a situation where  
democrats have the majority the primaries would first elect a median  
democratic candidate that would then be elected in the actual  
election by majority (at least if the Republicans followed the same  
practice and elected their median candidate in their primary). If all  
the democrat candidates would participate directly in the actual  
election, a probable outcome would be to elect not the median  
democratic candidate but one that is relatively close to the  
republicans. In the political system of the US where most of  
Washington is replaced by the new president to members of his own  
party electing a candidate that is the choice of the party that will  
rule makes some sense. But if one would seek for a president that  
represents the whole population (over republicans and democrats), a  
compromise candidate could make sense.

Note also that if one party goes directly to the election with  
several candidates and the other one arranges a preliminary it is  
possible that the one with multiple candidates will win since it is  
likely to have a more centrist candidate among its candidates than  
the other party.

> , and eliminating primaries could make more likely the conditions  
> under which IRV would select a winner against the preference of a  
> majority.

Didn't quite understand this scenario.

> The basic method is to select and vote for all candidates who one  
> judges as acceptable as winners. This is why it is named  
> "Approval." If voters are fully honest in this, and make reasonable  
> accomodation for the views and satisfaction of others (In other  
> words, A is my favorite, but I know that B is preferred by many who  
> don't like A so much, and I think of B as a reasonable choice for  
> the office as well), then the method clearly works to find a good  
> winner.

I think the name of the Approval method is not a very good one since  
the best (and quite sensible from sincere point of view too) strategy  
is not to vote based on which candidates one agrees but based on  
which candidates are probable winners and how one's own preferences  
relate to that. Maybe it  should be renamed to something like "pick  
the winner and the your favourite candidates" :-).

The end result may not be a very good one even if all voters would  
vote sincerely vote according to their view on which candidates are  
approvable. In this case the votes of those voters who find most  
candidates (especially the major ones) acceptable and those ones that  
strictly accept only some non major candidates would be wasted (from  
the point of view of deciding who the winner is). (Maybe someone  
thinks that excluding the extremists or those who are happy with any  
choice is a good thing, but this sure violates the one man one vote  
principle.) Strategic voting in Approval may thus be a good  
recommendation both from strategic and sincere point of view.

> For a poll to move a candidate from not-close to frontrunner  
> status, it would have to be drastically distorted. As I've  
> mentioned, there are more subtle, more serious, and less provable  
> forms of lying than this. I really don't think it's a matter for  
> special concern.

Ok, I don't claim that this vulnerability would be the most critical  
one. But making propaganda is common and generally accepted or  
understood. Light propaganda has similar but maybe weaker effect than  
a forged poll, but it is more acceptable and therefore risk of  
backfiring may be smaller. I have seen also promotion/claims of "two  
leading candidates" in a multiparty setting. Often it is beneficial  
to make some (or lots of) propaganda even if there were no guarantees  
that it will make the difference on who wins.

> As I mentioned, it could backfire. We don't know whether distorted  
> polls like this would improve or hurt a candidate's chance of  
> success, because only one of the possible effects was considered,  
> one which is thought to move the result in a direction favoring  
> those who distorted the polling. We would also have to consider the  
> effects which could move the vote in the opposite direction.

Ok, I didn't pay too much attention to this yet. Let's see if someone  
identifies some new properties.

Juho Laatu



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