On Jul 6, 2008, at 5:48 , Kevin Venzke wrote:
Hi Juho,
--- En date de : Jeu 3.7.08, Juho <[EMAIL PROTECTED]> a écrit :
That scenario was the simplest I could imagine. Only three
candidates. One strong candidate but below majority, one
weaker
runner-up, and third clearly weaker candidate. This was
also the most
threatening scenario from burial point of view that I could
imagine.
Are there simpler and more threatening ones?
Again, it isn't enough to isolate the scenario where the strategy
succeeds. What matters is the scenario where the strategy is worth
attempting.
Aren't we looking for scenarios where the strategy succeeds and are
therefore worth attempting? (except if fearing that the voters would
use some irrational strategies)
It is no consolation that the strategy does nothing when
the strategizers' candidate is the CW (due to a majority or due to
second preferences from the third candidate's supporters), or when
creating a cycle doesn't change the winner.
Yes, no incentives here.
The strategy has to hurt their own interests. Call the major
candidates
A and B, with the third candidate being C. A voters will use burial
strategy. Why would they not?
1. Because it could move the win from A to B: Impossible because this
would violate monotonicity.
2. Because it could elect C: Only when the B voters use burial
strategy
themselves. (We're assuming everyone will give full rankings of
course.)
Even though the strategy may hardly ever *work*, it's quite
unlikely that
it will hurt to try it, unless the opposing voters are using it too.
Ok, but there must be a reason why the A supporters would use the
strategy and the B supporters would not.
Compare with an IRV voter who uses burial because it feels right
and isn't
expected to make any difference.
IRV has quite different strategic incentives. Also irrational
strategies are a potential area of study (although not the default
case).
I don't think you have to be a thief,
or even trying to deter thieves, to use this strategy.
By the way:
C is a minor candidate who makes it onto the ballot without anybody
knowing much about him except his few supporters.
Yes, I guess we must pretty much assume so to make the strategy work.
Of course if there are only three candidates then also C is known by
all the voters although it may be clear that with sincere votes C has
practically no chances to win.
I guess you don't have
candidates like C in your country, since you always seem to speculate
about how many second preferences he would be getting in a real
election.
I think I was at least in most places referring to second positions
in the sincere preferences and the impact of that with respect to the
strategic incentives that the voters have.
Maybe Condorcet would encourage a better candidate than C to enter the
race (call him "D") but it's not clear that Condorcet would make C go
away or that there always would be a D candidate.
Even if A and B voters "sincerely" give C a second preference,
essentially
ranking the unknown option above the competition, I consider it hardly
any different from using burial strategy, in terms of its destructive
effect on the outcome.
Ok, any scenario with or without Condorcet winners will do. All we
need to show is that there are scenarios that are plausible in real
life (large public elections) and where use of burial strategy is
likely and successful (does more good than harm). Do you have some
specific set of votes in your mind that we could analyse?
(I may have leaned in some direction in my comments but the idea is
really to just identify one or more concrete cases (anticipated
opinions / poll results and strategy recommendations to the voters)
where the burial strategy would indeed work.)
Juho
Kevin Venzke
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