[EM] Instant Runoff Voting 3-candidate elections - pathologies considerably more common than you may have thought

[Kristofer Munsterhjelm]

Jonathan Lundell wrote:
> On Aug 27, 2010, at 12:48 PM, robert bristow-johnson wrote:
>> with Score and Approval, it's easy to mark your favorite candidate
>> (Score=99 or Approval=1).  and we know that Satan gets Score=0 or
>> Approval=0.  then what do you do with other candidates that you
>> might think are better than Satan?  that question has never been
>> answered by Clay.  and any answer must be of a strategic nature.
> 
> That is, to my mind, a fundamental problem with cardinal-rating
> systems--approval, borda, range, etc. Except for some trivial cases
> (notably two-candidate elections), the voting act is necessarily a
> strategic exercise. With an ordinal method (IRV, Condorcet (though
> one could I suppose specify a non-ordinal cycle breaker), Bucklin)
> it's at least possible (and usually a good idea) to cast a sincere
> ballot.

What do you think of Cardinal Weighted Pairwise? It uses a Condorcet 
matrix and sets the direction of defeats according to inferred ranking 
of the rated ballots, but the magnitude according to the rating. James 
Green-Armytage also suggests that a method that makes use of it 
normalize the ratings within the Smith set so the voters don't have to 
guess at what the Smith set will actually be.

> Why the latter is a good thing is a separate discussion... ---- 

I think Abd once argued that people will "automatically" vote in the 
Approval, maximum for all those I like better than the lesser evil, 
minimum for the rest, manner. IIRC, he called it "Neumann-van 
Morgenstern utilities".

I don't think so, so I think Approval burdens people with the need to be 
strategic, but there you go -- that's at least one person arguing that 
one should (and would) rather use strategic utilities.