[Date Prev][Date Next] [Thread Prev][Thread Next] [Date Index] [Thread Index]

# Re: Range Voting - the simpler better alternative to Condorcet voting

```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.

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.

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.
--
Barak A. Pearlmutter
Hamilton Institute & Dept Comp Sci, NUI Maynooth, Co. Kildare, Ireland
http://www.bcl.hamilton.ie/~barak/

```

Reply to: