[EM] IRV in action

[James Gilmour]

> > > Dave Ketchum had written:
> > > Here you need to understand the language IRV uses - they LIKE the word
> > > "majority", treading lightly on the fact that they are doing a majority of
> > > the ballots that remain to be used to determine a winner, and not a
> > > majority of total ballots.
> >
> > James Gilmour replied:
> > See my comment above.  Whatever other defects it may have, IRV does
> >ensure that
> > the winner has the support of half or more of those who are voting at
> the point
> > when the final decision is made.

Dave Ketchum replied:
> If my favorite is eliminated, but I despise my 2nd-ranked candidate only
> slightly less than my last choice, this doesn't mean I *support* the
> 2nd-ranked candidate in any meaningful sense.

Voters have many different reasons for ranking candidates in the ways they do.  In
preferential vote elections (mostly STV-PR), I have on some occasions marked my
positive preferences and left the rest blank (= "I don't care which of these gets
elected, but my preferences are all ahead of them for my vote").  On other
occasions I have marked my positive preferences, then marked my negative
preferences in reverse order (those I want to keep out), and then filled in the
spaces between the two groups, not in random order but with no strong feelings
either way about the "fill-in" candidates.

Unless you move to weighted preferences you cannot tell what the voter had in
mind, other than the preference order.  You may not like the word "support", but
if you have marked three preferences in the way you suggest, you have made a
statement about your support.  If your favourite is excluded (eliminated), you
have said I would prefer my second choice over my third choice.  That is quite
different from the action of the voter who does not mark any second or third
preference.


> The claim of IRV, or of
> any ranked method for that matter, to guarantee a "majority winner" is
> based on a fallacy of equivocation-- that the derived majority is
> somehow equivalent to an outright majority of voters.  In fact the only
> way to guarantee a majority is to manufacture one.

I don't think "majority" is the key issue.  The challenge is to decide which
candidate is the most representative of the voters.  IRV has obvious short-comings
in some circumstances.  Condorcet addresses some of those problems.


The next three paragraphs are just playing with words.

> A method which randomly dropped candidates until only two remain, and
> then selected the remaining candidate with the most votes, would have
> just as valid a claim of a "majority winner".  You could even
> sequentially eliminate candidates with the *most* first choice votes,
> until only two remain, and then declare the surviving candidate with the
> most votes a "majority winner".
>
> You can also guarantee an artificial majority by preventing all but two
> candidates from entering the race in the first place.  You can
> accomplish this, or at least make it more likely, by adopting
> restrictive ballot access rules, or by adopting a two-party-stable
> method such as FPTP, two-round runoff, or IRV.
>
> Some would claim that Condorcet methods choose the true majority, since
> the Condorcet winner is the majority winner in all pairwise contests.
> But since the pairwise majorities are all "artificial" in the above
> sense, any aggregation of these majorities will also be an artificial
> majority.


Dave had written:
> > > BTW - "majority" is a word that often needs qualification, such as "most
> > > of those who voted" or "most of the members".
> > James wrote:
> > "Majority" also needs further qualification when it is used with regard to
> > election results.  Here in the UK, the word has been distorted from
> its original
> > meaning ("more than half") to mean, in elections, "the winner's lead over the
> > second-placed candidate".  This distortion of the language goes well with our
> > placid acceptance of the distortions of FPTP in single-member districts!!

> Bart replied:
> I'm doubtful that the original meaning of "majority" was "more than
> half".  As far as I can tell, it simply meant "the larger portion".

Technically, you are correct.  The New Shorter English Dictionary (which is the
one I have on my PC), gives the following definitions and dates of first known
use:

1. The state or fact of being greater; superiority; pre-eminence. M16–E18 (ie
1530 - 1569).
2. The state of being of full age. M16 (ie 1700 - 1729).
3. The greater number or part; a number which is more than half the whole number;
spec. the larger party voting together in a deliberative assembly or electoral
body. L17 (ie 1670 -1699).
4. The number by which the votes cast for one party etc. exceed those for the next
in rank. M18 (ie 1730 - 1769).

Meaning 1 (the oldest) is not precise and has a wide range of dates.  In common
parlance here in the UK, "majority" has meaning 3, not meaning 1.  It is
interesting that meaning 4 arose nearly a century later than today's common use.