[EM] reply to Juho Laatu on range voting

Chris Benham chrisjbenham at optusnet.com.au
Mon Dec 18 03:04:48 PST 2006

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Warren Smith wrote:

>First:
>A theorem ( http://rangevoting.org/AppCW.html )
>indicates that range and approval voting both return the honest-voter Condorcet
>winner if all voters act strategically.  Basically, if we are not in
>the "prettiest cloud" but rather in the "I love/hate Nixon" emotional mode,
>then we vote max or min on Nixon.  Assuming all voters do that with
>their threshold placed somewhere between the two candidates they judge as most likely to win,
>(which they do because they are not strategic idiots)
>and assuming one of these two happens to be the honest-voter Condorcet winner, then
>theorem: Range & Approval both will elect the honest-voter Condorcet winner, but meanwhile
>Condorcet methods often will fail to do so.  [Juho Laatu claims misleadingly
>that "RV may still elect the Condorcet winner with quite good probability
>(but only with probability)."  Actually, under these assumptions, the probability is 1.
>Further, Condorcet methods with strategic voters will elect the honest-CW with
>merely a probability strictly below 1.]
>
I can't see that this set of assumptions is really that much different
from those needed to say that FPP will certainly elect the
Juho's statement].

>Second:
>The claim that "honest" Range Voters can have their votes
>outweighed by large factors by strategic ones, is correct.  However,
>(1) at least their honest
>vote will never actually work against them (e.g. compared to not voting at all)
>
The chance of that happening in practice is very small, I'd say
insignificant if  the Condorcet method meets mono-raise (like Schulze
and DMC and most others). Those methods also allow equal-ranking at the
top, so voters in fear of being bitten by Participation
failure can avoid it by submitting approval votes.

>(2) their honest statement "X is my favorite" in their vote, will never hurt them.
>
You mean their honest statement "X is *one* of my favourites (plural)"
will never hurt them (assuming you mean "hurt them in comparison
to some other way of voting").

>..consider a Condorcet election.  Gore loses to Bush thanks to a Nader spoiler
>effect.  The Nader voters complain "the voting system penalized us for honestly ordering
>honest ordering, without being penalized."
>
If the election is close enough in comparison to the number of available
slots on the range ballot, then the Nader voters can of course
still be penalised  "for honestly ordering Nader top, Gore second".

>Second:
>The claim that "honest" Range Voters can have their votes
>outweighed by large factors by strategic ones, is correct.  However,..
>
>Anyhow such outweighing
>
>
>(b) is entirely their own fault and hence is self-correcting over time and not a
>valid attack on the voting system.
>
>
>
I reject the idea that voting honestly is a "fault". The voting system
should try to minimise the advantage of  strategists over
sincere voters, and of informed strategists over less well informed and
zero-info. strategists. It should give the voter a clear
way of voting sincerely, and if there is a zero-info. strategy it should
be straight-forward and similar to sincere voting.

A minimum standard is that the voting method should give good results in
the zero-info. case with strategic voters.

Say sincere ratings are:

48: A10>B4>C0
47: B10>C6>A0
04: C10>B4>A0

B is the Condorcet and big sincere ratings winner, but if these voters
all use the best 0-info. Range/Approval strategy
C the sincere ratings loser (SU worst) wins.

Chris Benham

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