[EM] IRV and Condorcet operating identically

[Dave Ketchum]

We seem to disagree as to the difference between IRV and Condorcet, so 
time for an example:

Given:
      C - a least of evils with 40 SOLID support.
      L - a least of evils with 60 SOLID support.
      U - an up and coming third party candidate attractive to some L voters.

40 C
0-29 U,L - some, but minority, support by L voters for U (here I lump 
together 0 votes for U,L thru 29 votes for U,L, since results are 
identical for the group).
60-31 L - remaining L voters.
      IRV and Condorcet both drop U as a minority, and L wins.

40 C
31-39 U,L - U is gaining.
29-21 L
      IRV drops the minority L voters and C wins over U.
      Condorcet sees 40C>35U, 35U>25L, 60L>40C - hopefully we agree that L 
wins here.
      Not liking C winning here is why I fight for Condorcet.

40 C
41-60 U,L
19-0 L
      IRV awards to U.
      Condorcet sees 60L>40C, 50U>40C, 50U>10L - U wins since no cycle.

For BOTH of these ranked ballot methods the third party support that was a 
spoiler in Plurality voting gets measured, but does not disturb results.

Make third party support a bit stronger and IRV has a spoiler problem 
while Condorcet does not.

Make third party support strong enough and both agree that third party 
candidates CAN win.

Thus with both, but especially with Condorcet, voters can vote their 
desires with expectation that their votes will count.

On Thu, 27 Feb 2003 19:49:13 +0100 (CET) Venzke Kevin wrote:

>  --- Dave Ketchum <davek at clarityconnect.com> a écrit :
> 
>>On Tue, 25 Feb 2003 09:23:41 +0100 (CET) Venzke
>>Kevin wrote:
>>
>>
>>>I wonder if the only reason IRV has more apparent
>>>backing than approval or Condorcet is because it
>>>
>>would
>>
>>>permit our present politicians to be elected even
>>>
>>more
>>
>>The above makes no sense, for IRV and Condorcet use
>>identical ballots and, 
>>most of the time, award identical winners. 
>>
> 
> They are only likely to award identical winners when
> the voters and candidates think the rules are IRV when
> they're voting and entering the race, respectively. 
> This is because more than two candidates may be viable
> under Condorcet rules.  Under IRV, usually only two
> candidates can really win, and the voters know it and
> vote that way; the "compromise candidates" know it,
> too, and don't enter the race.
> 
Huh!  Even in Plurality, where the spoiler problem made winning very 
difficult for "compromise candidates", they FOR SURE did enter the race.
With Plurality's spoiler problem gone they have a better chance.

Really better to talk of ranked ballots and not say too much about 
IRV/Condorcet - proper voter thinking is identidal except when voters 
know that in theory IRV can be gimmicked with sufficient knowledge, and 
dream that they know enough to do that successfully.
> 
>>That is:
>>      Both get rid of Plurality's spoiler problem,
>>
> 
> IRV only reliably does this when the voters
> acknowledge that they have to give favor to one of the
> two lesser evils.  But how different is that from
> Plurality?
> 
In BOTH IRV and Condorcet the voters need to know that they had best vote 
for one of the major candidates - that, unlike Plurality, they can vote 
their true desire first without worry about spoilers (except IRV has a 
bit of spoiler trouble).
> 
>>which should be 
>>attractive to politicians.
>>
> 
> Condorcet eliminates the spoiler problem by permitting
> voters to vote (more) sincerely, and (thus) by making
> more candidates viable.  Why on earth would that be
> attractive to our present politicians?
> 
A politician who has retired to a safe elected home may not see any joy.

A politician who worries about Plurality spoiler problems should be 
looking for something better.

A politician who thinks of being a third candidate should be interested.

Remember that, while general elections are often owned by one party,
primaries are fair game, even within parties that expect to win in Nov.
> 
>>      Both thus encourage voting for third party
>>compromise candidates, 
>>which could make successful politicians nervous.
>>
> 
> At the risk of being repetitive:
> They don't have to be too nervous with IRV.  If a
> third party candidate becomes a spoiler, the winner
> will still be a "lesser evil."
> But they *would* have to be very nervous under
> Condorcet rules, because they could lose.

I tried to clarify the similarity of IRV and Condorcet above.
> 
> If you put voting systems in order of to what degree
> they preserve the problem of the election of the
> lesser of two evils, I would draw it like this:
> IRV - Plurality - Approval - Condorcet.
> My conclusion is that people who support IRV, while
> understanding the objections to it, must have a
> different motivation.  I suspect consequently that
> support for IRV can't be easily converted to support
> for a different system.

So we disagree, for in this listing I would place IRV next to Condorcet.
> 
> Stepjak

-- 
  davek at clarityconnect.com    http://www.clarityconnect.com/webpages3/davek
   Dave Ketchum    108 Halstead Ave, Owego, NY  13827-1708    607-687-5026
              Do to no one what you would not want done to you.
                    If you want peace, work for justice.

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