At 10:03 PM 5/26/2010, robert bristow-johnson wrote:
On May 26, 2010, at 8:19 PM, Dave Ketchum wrote:
[about IRV]
Backers make a big deal of "majority" - but it is of the final
stacks, not of all ballots.
what it is, is *a* majority. for a particular pair that is left
standing after the other candidates are eliminated by the IRV STV
rules (which is the essential problem with IRV). assuming no ties,
each pair of candidates drawn from the candidate pool has an intrinsic
majority. the question is: which majority is the salient majority?
Once upon a time, there would have been no question. "Majority" has a
few meanings, but it never meant "majority of all those voting for
the top two, excluding all other ballots cast in the same election."
Robert's Rules calls it, in the counting rules, just "majority," and
that allowed IRV enthusiasts to believe that they meant last-round
majority, if they didn't read too carefully, and FairVote went on
promoting this even after it was pointed out that Robert's Rules, in
the instructions for the clerk, mentions that voters should be told
that if they don't rank all the candidates, there might be a failure
to get a majority, and the election would have to be repeated. It is
totally explicit.
In San Francisco, the voter information pamphlet on the RCV question
said that the "candidates would still be required to gain a majority
of the votes." It didn't say "majority of the votes for the top two,
left after eliminations." It said "majority of the votes," and unless
someone read the question carefully, they could easily think that
"majority of the votes" meant majority of *all* the votes. My guess
is that the people on the ballot information committee thought that
too. They had simply swallowed FairVote propaganda, which hasn't been
really explicit about this majority thing, most of the time.
I've pointed out that this concept of "last round majority" could be
used to claim that there is a very simple change to Plurality that
allows it to always find a majority. This is far cheaper than IRV and
produces the same results, almost all the time, in nonpartisan elections.
It's simply. Just use the STV elimination and count it as if it were
IRV. Eliminate the lowest vote-getter in each round, and ballots
which only have a vote for that candidate, until a candidate left has
a majority of the remaining votes. If you want a more sophisticated
version, allow the ballot to approve multiple candidates. Presto! A
majority in every election.
Now, if that isn't a majority, why is the IRV majority a majority?
In fact, we can take the process one step further. Wouldn't it be
desirable to have unanimity in every election? Very simple to do, eh?
Suppose Tom, Dick, and Harry share all the top rank votes, and
Joe gets all the 2nd rank. Then if raced in pairs Joe would get
twice the votes of each of them - but Joe is invisible in IRV.
or, we could change Joe's name to "Andy" and Tom and Dick to "Bob" and
"Kurt", leave Harry out of it, and this hypothetical becomes less
hypothetical.
Cool. Leave Hairy out of it. Much easier.
David didn't exactly express this well. He means that Joe could be
the unanimous choice of every voter in second rank, and lose, simply
because the first rank votes of Joe were less than those of Tom and
Dick. Those first rank votes could be almost equally divided, so we
have an IRV winner based on one-third of the vote (suppose the Joe
voters truncate), whereas Joe would beat that candidate two to one in
a direct face-off. That's horrible performance. To be sure, that's
extreme. The situation in Burlington wasn't that bad, just an
ordinary IRV failure to respect a majority position, in favor of the
Democrat, who would have beaten all the other candidates in pairwise
races, and probably would have won under Bucklin, as well. Or
Approval or Range, my guess.
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