[EM] "scored condorcet", etc

[Rob Brown]

Kevin Venzke <stepjak <at> yahoo.fr> writes:
> Beatpath(wv) satisfies clone independence, monotonicity,
> plurality, minimal defense, Condorcet Loser, Local IIA,
> always elects from Schwartz, always elects from the CDTT..
> It'll be very hard to meet the same properties if you
>  design method from scratch.

Fair enough.  The biggest problem I have with beatpath is that I CAN'T ACTUALLY
ELECT ANYONE WITH IT.  (sorry if that looks like shouting, but I can't
emphasize that point enough)

No one is using beatpath in the real world.  I actually *can* elect people with
IRV (since I am lucky enough to live in San Francisco), even though most
election methods geeks know it's inferior to condorcet methods.  Why is that? 
(and more importantly, why is plurality still so much more common than any
ranked system?)

I don't question that meeting lots of criteria is good, but sometimes I question
whether some of the people on this list tend to see things in such black and
white terms that they are really missing some important points.  For instance,
with regard to, say, the "clone independence" criterion:  is it possible that
two methods both technically fail this criterion, but that one does a whole lot
better than the other on it?  For instance, plurality utterly fails this. 
Minmax....seems to me that it would only affected by clone candidates in the
most contrived situations.  I think that saying that something "fails", without
saying "how badly it fails", is misleading.

So if MinMax (or the "MinSum" method I proposed) fails some criteria, but "only
by a little bit", while having other desirable properties that can make it more
"marketable" (i.e. you can actually explain how it is tabulated to regular
people in a way they will understand, and show the results in a way they will
understand), I think that could far outweigh its technical imperfections.
 
> I'm not so convinced that it's valuable
> for a method to be tunable. I can't imagine how you could really use
> this to fix a perceived problem.

Well, let me give an example of tunability that currently exists in the real
world: the "two-thirds majority" required to, for instance, ammend the US
constition.

Why two-thirds?  It's not a magic number.  It could have been three-fourths (as
it is for final adoption of any constitutional amendment in state legistatures),
or three-fifths, or 70 percent, or whatever.  Such a thing is inherently
tunable, by simply adjusting a variable, rather than by selecting a completely
different system.  Typically the value is not going to be adjusted for each
election but it will be selected when framing a new constution or by-laws,
allowing the framers to select whatever value they want to strike the right
balance (in this case between flexibility and stability).

Now, with electing a single candidate, things are different, but tunabilily
could still be valuable.  Here is an example:

Say one election method tends to pick a non-controversial, middle ground
candidate.  Someone that doesn't offend anyone but isn't necessarily loved by
many people either.

Say another method tends to favor a candidate that is strongly favored by many,
disregarding whether that candidate is despised by a few.

Now, wouldn't it be nice if you could, when writing a new constitution or
by-laws, decide the exact balance that is desired, to encourage harmony while
also allowing for healthy debate?  Rather than having to say "should we use
beatpath or minmax or approval or IRV or plurality?", they could say "we'll use
the Tun-o-matic system with the harmony factor set to .7".

-rob