[EM] To Blake, re: pushover examples

Blake Cretney bcretney at postmark.net
Mon Apr 30 22:20:30 PDT 2001

On Mon, 30 Apr 2001 02:43:11 -0000
"MIKE OSSIPOFF" <nkklrp at hotmail.com> wrote:

> Blake continues:
> But if they
> want their ballot to be fully counted, they can still randomly rank
> the rest of their ballot.
> I reply:
> Blake is referring to the fact that in a 0-info election, one can
> gain some expectation by randomly ranking some equally-preferred
> bottom candidates, something that could pay off only in a natural
> circular tie. Blake, I asked you for examples of how that & your
> strategy objection can cause bad consequences. I notice that you
> haven't posted any such examples. It couldn't be, could it, that
> because you don't have any examples in which those wv strategy
> cause serious consequences?

When you talk about "serious consequences", you mean from a global
perspective.  In other words, you are referring to situations where
you don't approve of the outcome.

When I talk about voters being punished, I mean from the perspective
of the individual voter.  That's the perspective that actually
motivates how a voter votes.
> Blake continues:
> Then, I come along and point out that wv doesn't really do any good
> after all.
> I reply:
> Thank you, but would you show some examples showing how wv produces
> seriously bad results, results as bad as the Margins results that
> wv gets rid of?

45 A B C
20 B A C
35 C B A

If the A 1st voters randomly rank after A, and split evenly, then A
will win, which is the kind of bad result that concerns you.  So,
that's one reason I say wv doesn't do any good.  Voters can avoid the
penalty by randomly ranking.

If you manage to convince people that truncation in this example is a
major strategy problem for margins, reasonable people will conclude
that random-ranking is also a major strategy problem for wv.

Of course, I don't consider either a major strategy problem, and not
just because I want to preserve at least one Condorcet method.

> Blake continues:
> Of
> course, that isn't considering the truncation-for-sheer-spite
> strategy.
> I reply:
> What isn't considering it. I'm considering it. That's one reason why
> there can be truncation. Other reasons are strategic, and lazy, and
> principled--I'd refuse to rank anyone unacceptable, just as I'd
> to rank an unacceptable voting system in a voing system poll.

Actually, I was referring to your examples where people truncate
against their best interests, either out of spite, or because it makes
your example work.

As for these various reasons for truncation, I think you may be going
beyond a reasonable concept of a sincere CW.  For example, I am
concerned that factions might use strategy to affect the election
result, including by defeating the sincere CW.  But you seem to want
to preserve people's preferences even if they can't be bothered to
express them, or if they don't want to express them, independent of
strategy concerns.

If someone can't be bothered to rank B over C, I don't consider the
information that they actually prefer B to C to be very important.  I
don't think an opinion is likely to be well thought out, if the voter
can't even be bothered to mark it on the ballot.  The next step would
be to worry about subconscious preferences the voter doesn't even know
he or she has.

> Blake continues:
> , or randomly rank, in either margins or
> wv.  If you're tempted to use partial rankings as a strategy, order
> reversal is even better.
> I reply:
> Are you sure that there aren't situations where truncation is safe
> but order-reversal isn't? But sure, order-reversal is more likely to
> get results than truncation is. When you say that order-reversal is
> an even better offensive strategy in Margins, it isn't clear how
> you consider that a Margins advantage.

It's an even better strategy in both, not just margins.  So, it would
make more sense to worry about order-reversal than truncation.

The reason you truncate, is that you have a victory, like X>Y, and you
want to increase it.  At some point, the victory gets to  be enough to
defeat Y.  Then, either one of the truncator's preferred candidate's
wins, or the strategy back-fires.  The only reason you would truncate
is if you expect a better result when Y is sufficiently defeated.  If
that is the case, it makes sense to do all you can to sufficiently
defeat Y.

So, we're actually better off if people believe you when you talk
about how great a strategy truncation is.  This prevents them from
using more sophisticated strategies.

> But I agree with you: I & others will be making much use of Margins'
> easy order-reversal opportunities if Margins is enacted.

Good luck.

Blake Cretney   http://www.fortunecity.com/meltingpot/harrow/124/path

Ranked Pairs gives the ranking of the options that always reflects 
the majority preference between any two options, except in order to
reflect majority preferences with greater margins. 
(B. T. Zavist & T. Tideman, "Complete independence  of clones in the 
ranked pairs rule", Social choice and welfare, vol 6, 167-173, 1989)

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