[Election-Methods] RELEASE: Instant Runoff Voting

[James Gilmour]

Aaron Armitage > Sent: Tuesday, July 29, 2008 1:11 AM
> IRV and all 
> other ranked choice systems ask for the same input from 
> voters

This is where you make your first mistake.  IRV and other ranked choice voting system do not all ask for the same input from the
voters.  IRV asks voters to mark preferences in the knowledge that those preferences will be used as contingency choices, so that a
later preference can in no way affect the chance of election of an earlier preference.  Some other ranked choice voting systems, in
a variety of different ways, make simultaneous use of all the preference information recorded on the ballot paper, such that the
later preferences can affect the chances of election of the earlier preferences.  The voters know in advance which counting rules
will be used in any particular election and modify their marking of preferences accordingly.  So the inputs are not the same.


> and produce the same kind of output, namely a single 
> winner. 

Here is your second mistake.  Both kinds of voting system do result in the election of a single winner, but the outcome (output) can
be quite different in terms of what that winner represents.  In the case of IRV that winner is the contingency choice, with all the
implications of that.  In Condorcet, the winner may be decided in a very different way from IRV and represent something very
different in relation to the voters.  In a Borda count, the winner may represent some sort of compromise even when there is one
candidate who has an absolute majority of the first preference votes.  So all these outputs are quite different.


> For you to say they differ so fundamentally that no 
> common standard can be appealed to looks an awful lot like 
> special pleading.

There was no special pleading  -  just a request that the differences in the inputs and outputs be recognised for what they are -
fundamental - and not ignored.


> And how can you argue that we should adopt 
> IRV instead of Condorcet or Borda or Bucklin if you have to 
> common standard from which to argue that IRV is better?

I don't think I have said anywhere that "we" should adopt IRV instead of the other voting systems, but since you ask:

I would reject Borda because it can elect a candidate other than the one with an absolute majority of the first preference votes.

I would reject Buckilin because it does not comply with "one person, one vote".

I am VERY sympathetic to Condorcet and think the basic concept is "sellable" to the electors (presented as a "head-to-head
tournament"), despite the inevitable opposition of most politicians, big business and the media moguls.  I foresee bigger problems
in selling any of various cycle-breaking and tie-breaking solutions that have been proposed.  But the real problem with Condorcet is
the weak Condorcet winner.  It is my judgement (based on long experience as a practical reformer, but only in the UK) that such an
outcome would not be politically acceptable to the electorate in an election to public office.  Such a winner would, of course, be
the real Condorcet winner, but that would not, of itself, make the result politically acceptable to real voters.

IRV has, of course, a corresponding "political" weakness, in that it can reject the candidate who might be everyone's second choice
(the Condorcet winner).  But experience shows that the electors are prepared to accept that outcome.

James Gilmour







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