[Election-Methods] RELEASE: Instant Runoff Voting (Chris Benham)

[Chris Benham]

Kathy,
Imagine  that  Approval is used to elect the  US President and 
as in the current campaign the Republicans  are fielding one
candidate, McCain.  Does that mean that the big fight for the
Democrat nomination between  Clinton and Obama we've just
seen would in the Approval scenario be completely unnecessary?

Why not simply endorse both candidates?  After all, one cannot
possibly spoil the election for the other because Approval has
no spoiler problem. Voters simply approve candidates or not
completely regardless of what other candidates are on the ballot,
right?

I  think that in practical effect Approval  does have a "spoiler" or
split-vote problem  that would be sufficient for the Democrats to
still want to endorse one candidate only.


What I actually wrote in my initial post on the 5  "fairness
principles in your paper (regarding IIA):

In practical effect  *no* method meets this.Approval and Range can be said to meet  
Independence of Irrelevant Alternatives (IIA) only if the votes are interpreted as the voters giving 
ratings on some fixed scale that is independent of the actual candidates. 

On this perverse interpretation Approval and Range do not reduce to  FPP in the 2 candidate election,
in violation of  Dopp's "fairness principle 4":

"Any candidate who is the favorite [first] choice of a majority of voters should win."
(approval or non-approval counts as "rating" on a 2-point  scale).

This latter point you seem to implicitly acknowledge in one of your recent posts:

"In actuality, if these are the same voters both before and after you
add another candidate C, then your first example with two candidates,
to be consistent with your second example with three candidates should
be:

25 A
40 AB
35 B

so that B wins in the first example AND in the second when another
candidate is introduced."


Chris Benham


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