RE: [EM] 12/30/02 - Alex, Irving still holds the Trump Card:

[Adam Tarr]

Alex wrote:

As to Adam's point that IRV, Approval, and Condorcet all give the same
result in the case of 2 strong front-runners:

Say we have

40% Left>Center>Right
11% Center>Left>Right
 9% Center>Right>Left
40% Right>Center>Left

IRV selects Left, Condorcet selects Center, and Approval can select any of
the above depending on the choices of the voters, although Right is the
least likely outcome.

Absolutely, I agree. My response was sort of overlooking the "weak center" example that is popular on this list. I was thinking along the lines of a more trivial case, such as

10% Libertarian>Republican
39% Republican
37% Democrat
14% Green>Democrat

Assuming reasonably rational voters, approval, Condorcet, IRV, top two runoff, Bucklin, MCA, cardinal rankings, et cetera... will all give the same result. Only Borda and Plurality do not, for they still encourage swapping your favorite with your second place.

I agree that your example (the standard list example) reveals differences, and that these differences favor approval, Condorcet, Bucklin, MCA, and cardinal rankings over IRV and top two runoff. It seems from previous posts that Donald and other IRV backers do not really see a distinction between the left, center, right example and the one I just gave. In their minds, the center candidate is weak, just like the Green and Libertarian candidates I show above. The fact that your center candidate is preferred by a majority over every other candidate just doesn't strike them as significant.

-Adam


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