[Election-Methods] Borda-elimination, a Condorcet method for public elections?

[James Gilmour]

> On Dec 22, 2007, at 6:45 AM, James Gilmour wrote:
> > If you wish to utilise in some way all the information that could be
> > recorded on a preferential ballot, that is a completely
> > different voting system from IRV, with different objectives.  The  
> > preferences are no longer 'contingency choices', but take on a new
> > function depending on the detail of the voting system.  It is almost  
> > certain that the voters would mark their ballots in a different
> > way in an election by such a voting system from how they would mark  
> > their contingency choices in an election by IRV.

Jonathan Lundell > Sent: 22 December 2007 19:00
> This seems plausible enough (and certainly IRV voters should be  
> instructed along contingency lines). WRT marking ballots differently,  
> setting manipulation aside, and considering only contingency vs  
> preferential ranking, do you have an example or two of how and why a  
> voter might end up with different ballots in the two contexts?

That is a very fair question, Jonathan, but I do not have any practical examples to indicate the circumstances in which voters might
mark their preferences differently.  We do not use IRV for any public elections in the UK and so I have no real example to draw on.
And it is very difficult to invent examples based on direct, single-winner elections from other countries without a lot of relevant
political information, because there is little agreement about how real voters would respond, as I have seen repeatedly in
discussions of such examples as Bush-Nader-Gore.  I am not a specialist in voter behaviour and so have no special insights on which
to base "real" predictions.

That said, one situation where IRV ballots and Condorcet ballots might be completed similarly would be when there are three strong
front-runners.  Then IRV voters and Condorcet voters might well complete their preferential ballots similarly.  When the "everyone's
second choice" candidate had very weak first preference support, they might well complete the ballots differently: in Condorcet the
supporters of the two strong wings might truncate in an attempt to prevent the weak second choice from coming through the middle.
But that suggestion is contentious, as I have seen in other discussions and there is no agreement about how voters would really
react.

Just a word about terminology: IRV ballots, Condorcet ballots and Borda ballots are all 'preferential' ballots.  The difference is
that in IRV the successive preferences are brought into play only on the stated contingency; Borda tries to sum all the preferences
instantly into one value; Condorcet perhaps lies somewhere between these two extremes, depending on the sequence of events in the
individual count.

James Gilmour

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