[EM] Approval reducing to Plurality

Kristofer Munsterhjelm km-elmet at broadpark.no
Wed Sep 1 00:02:53 PDT 2010

robert bristow-johnson wrote:
> On Aug 31, 2010, at 4:03 PM, Raph Frank wrote:
>> On Tue, Aug 31, 2010 at 11:08 AM, Juho <juho4880 at yahoo.co.uk> wrote:
>>> The serious problems of Approval come into play only when there are more
>>> than two potential winners. As long as T1 and T2 are called "T" (i.e.
>>> "minor") things are fine.
>> I disagree.  However, we don't really know the how the mechanics of
>> approval will work out in practice.
>> I think that it would allow a little utility weighting to come into
>> it.  Voters who see two candidates as being almost identical would
>> probably just approve both.
> i can confess that i am currently planning to bullet two (out of about 
> 20, with limit 6) candidates this November in this virtual approval 
> election of state senators.  the candidates are clearly different, but i 
> like them both.  neither are incumbent.  there are two "open" seats and 
> 3 credible non-incumbents to fill them.  so it's kinda like musical chairs.
> and my worry is that voting for one will harm the other.

Vote for both of them. In the worst case that they cancel out, it'll be 
the same as if you didn't vote for either, except that you've increased 
the chance that the winners will include at least one of them.

>> It is like condorcet with a slight utility bias.
> what's the utility?  that it's easy to understand?  or something else?

It's utility as in utilitarianism. Abd likes to use the example of a 
pizza, where a majority likes one type of topping slightly more than 
another, but there's a small minority who absolutely detests the first 
type. Then, it is argued, the good thing is to pick the second topping 
because the majority loses less than the minority gains, even though 
that violates the principle of majority rule.

In that sense, Range has a utility bias - it picks winners based on 
(reported) utility rather than on the number of voters who state the 
preference. The problem is that reported utility can easily be 
falsified, and so Range reduces to Approval. CWP is probably better than 
raw Range at forcing the voter to be consistent, but in so doing, it 
fails many properties that Range advocates consider important, like the 
utility bias above - since the direction of the pairwise victories are 
determined by ranking, a method based on CWP passes Majority even in the 
pizza example above.

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