[EM] Is Condorcet The Turkey?

[Forest Simmons]

On Sun, 8 Jun 2003 Dgamble997 at aol.com wrote:

>
> This is exactly what I meant. Condorcet simultaneously compares all pairs of
> candidates. The voter, has for example, ranked the candidates A 1st, B 2nd, C
> 3rd, D 4th, etc. In simultaneous paired comparisons the 4th Preference D is
> rated as having equal value to the 1st preference A. In pairwise comparisons
> between A and another candidate E this A>B>C>D vote counts one for A, likewise in
> a similar DE pairwise comparison it will count one for D. Since the voter has
> ranked A 1st and D 4th s/he clearly supports A more than D.
>
> IRV has the advantage that lower preferences are not considered until higher
> preferences have been eliminated. This removes the problem that A is preferred
> to D and yet in a Condorcet count both are counted as one against candidate
> E. If A, B and C are eliminated we can assume (safely) the voter will
> wholehearted support D as his/her highest choice remaining in the count.
>

Among methods depending on ranked ballots Borda is the simplest to explain
(the winner is the candidate with the highest average rank) and the method
that best takes into account the likely relative support of the person who
marked this ballot for the candidates A thru E.

Here's an example that shows the superiority of Borda over IRV in this
regard.  Each faction has its fantasy candidate, and every faction thinks
that candidate X is also perfectly acceptable.

Sincere preferences:

21 A>X>> (various)
20 B>X> (various)
19 C>X>>...
18 D>X>> ...
17 E>X>> ...
 5 X>>(various)

Borda elects candidate X, while IRV eliminates X in the first round,
unless enough voters betray their favorite on their ballot rankings.

Why do you prefer IRV to Borda?

I, for one, prefer IRV to Borda because Borda has clone problems that IRV
doesn't have, and because IRV generally gives less incentive for a voter
to falsify preferences, though the incentive is still there as this
example and many others on this EM list show.

What advantage is there to weighing higher preferences more if those
preferences are insincere?

The best Condorcet methods seem to be the only purely ranked methods that
do not give significant incentive for voting insincerely in important
practical scenarios.

Personally, I believe that if we are going to go a mile to get ranked
ballots, we should go the extra foot to get the approval cutoff, too.

Furthermore, I believe that (in order of both "bang" and "buck") Candidate
Proxy, Approval, and Majority Choice Approval (MCA) are the three methods
that give the most bang for the buck, and that all of these are superior
to IRV in "bang" (not to mention "buck").

Approval and MCA satisfy the important Favorite Betrayal Criterion that is
not satisfied by IRV, Borda, or any other standard method based on purely
ranked ballots (not even the best Condorcet methods).

Even in ultra simple Candidate Proxy there is less incentive to betray
favorite than in IRV.  In the above example, voters could safely vote for
their favorites to represent them as proxies, especially if the election
completion method used in the proxy convention happened to be Approval.

Candidate Proxy has many advantages, including simplicity, over IRV, but
IRV could hardly have any advantage over Candidate Proxy because most IRV
voters use "candidate cards" or the equivalent to guide their ballot
marking.

Forest