Re: Range Voting - the simpler better alternative to Condorcet voting
Barak A. Pearlmutter writes:
> You also make the point
>
>> 60x A=60,B=40
>> 40x B=60,A=40
>
>> It only takes six of the second group to vote B=99,A=0 to change the
>> outcome, which is a major victory for the extreme supporters but a
>> loss for honest moderates.
>
> I think your point is that, with Range Voting, if *some* of the voters
> vote strategically while others don't, the ones who vote strategically
> carry extra weight in the election.
>
> (a) This is ***EXACTLY RIGHT***!!! In fact, that is the *definition*
> of strategic voting. If voting strategically didn't give a voter
> extra power to influence the election in their favour, we wouldn't
> call it "strategic."
>
> (b) This is also true of Condorcet.
Which six voters in that example have the ability to change the
outcome of that Condorcet election by voting strategically rather than
honestly?
My point was not that strategy is possible. My point is that the
obvious strategy under Range Voting is almost always optimal if you
look only at one election, but that it has factionalizing effects in
the longer run because it encourages artifically strong expression of
opinions. Effective strategies for Condorcet methods are harder to
judge, which encourages honest voting. This in turn encourages good
positions from candidates, since they know more accurately what the
electorate thinks is important.
> Unfortunately (Arrows theorem etc) there is no voting system for >2
> candidates which avoids the possibility of strategic voting. And
> Condorcet is, unfortunately, in fact, particularly susceptible to
> strategic voting. In Condorcet, if all the voters vote strategically,
> you often get a really bad candidate winning; this is the DH3
> pathology, see http://rangevoting.org/DH3.html for details. But with
> Range Voting, if everyone votes strategically, you get ... the "honest
> Condorcet" winner. Which isn't really so bad.
In other words, if everyone in a Condorcet method has accurate
knowledge of how other voters really feel *and* ignores how strategy
compels others to vote, they can choose a poor strategy. This means
that voters should vote honestly rather than use a poor strategy, but
is really not a very interesting observation.
There are similar problems in strategic Range Voting from approval
cutoffs. Universal strategic Range Voting does not guarantee the
"honest Condorcet" winner.
> As an addendum: in Range Voting voters are told to rate the
> candidates, with min/max for their least/most favoured candidates. So
> in your particular example with only two candidates, the actual votes
> would have been
> 60x A=99,B=0
> 40x A=0,B=99
> which would leave no opportunity for strategic voting. But that's no
> great trick, since there are only two candidates. With >2 candidates,
> it is easy to make examples where strategic voting by Range Voting
> voters would make sense.
Horse pocky. Where are voters told to do this? The first example on
http://rangevoting.org/ talks about the Olympic scoring system. When
was the last time an Olympic judge scored one competitor 0.0 and
another 10.0 in one event? The "How range voting works" section makes
no mention of it, either.
I really should know better by now, but I am still surprised when
Range Voting advocates throw out such bogus claims.
Michael Poole
Reply to: