|
The exercise to describe Condorcet in 12 words or less emphasizes
something I’ve been thinking of for a while. A “method” is a
collection of processes, and what the list came up with for a short description
of a Condorcet-based method makes very clear what the highest-level subdivision
of a an “election method” is: “Tally the round-robin
pairings using the voters' orders of preference.” You need a process to count the votes, and you need
a process to collect the input to the tally process. That’s my definition
of an EM, although I’d word it the other way around. Election Method: n. A combination of a procedure for collecting voter
preferences and an algorithm for counting votes. From a purely analytical standpoint, these can be dealt with separately
and I believe it is much easier to do so. I take no sides on the IRV vs
Condorcet discussion, but observe that you can do neither if the collection
process only supports plurality. Any improvement over plurality needs some of
ranked-ballot input, and it seems to me to be pointless to be debating the
attributes of tallying algorithms if there’s no input to talley except
first-place votes. Folks on this list tend to concentrate on the properties of the
algorithm for the “counting votes algorithm”, and that is proper.
But in order to do so there are unstated assumptions regarding how the
preferences were collected. Any Condorcet-based method that only notes
voter x preferred A to B and voter y preferred A to B but doesn’t take
into account that voter x preferred C to B while voter y preferred B to C will
necessarily be wrong in assuming that x’s and y’s A>B votes are
equal, and there’s no way to resolve that just from the pairwise matrix.
It just can’t show the difference between A>C>B and A>B ballots.
(Yes, voter x’s C>B vote will show up there, but B still gets the same
benefit from x and y, even though they didn’t intend to equally support
B). From a terminology standpoint, IRV has an instant advantage. Every
voter I know understands run-offs, and every voter I know would prefer to only
vote once to express their preferences. So IRV advocates need the voters to
adopt ranked-ballots. And of course, without ranked-ballots, you can’t
have Condorcet-based tallying procedures. Ranked ballots also support plurality
and approval –based methods. So pretty much everyone should work toward
getting the collection procedure to provide ranked-ballots as input to an arbitrary
tally algorithm.. To re-open an old discussion, I would argue strongly that an even more
general ballot would be appropriate for any Condorcet-based method. If there
are 5 candidates in the race I might select the A>B>C>D>E ballot,
but if you take A, B, and E out of the race, in the “round robin” I
might rationally choose D>C, because all of the issues that made C better
than D were covered by A and B. With them out of the picture, D may agree with
me on more high-priority issues than C. So I would argue quite strongly that if you use a pairwise matrix as
your tally mechanism, you allow each voter to fill in their pair-wise
preferences. If you don’t, the system is not “transparent”
and can’t be backed-up by voters’ ballots. That would be a lot
harder to sell (but it’s trivial to implement) |
---- Election-methods mailing list - see http://electorama.com/em for list info
