On Jun 5, 2009, at 12:58 AM, Árpád Magosányi wrote:
I guess the list might have opininons in this discussion.
2009/6/4 Warren Smith <[email protected]>
> I am using "winning strategy" in the game theory sense.
--voting is then an N-player game with N very large.
Most or all attempts to look at voting in that way have been
unsuccessful.
Game theory is best suited to 2-player games and most of it breaks
down with more than 2 players.
I am not an expert in game theory, but I feel that the existence of
term "tactical voting" shows that it can say things about elections.
I always hear political analysts talking about best strategies for
parties in an election campaign. Also there are a lot of voting
criteria concerned with what happens when candidates do things (e.g.
bring in clones), or voters do things (modify ballot in some or
other way, or do not vote).
> Range voting also have a problem with tactical voting. As tactical
voting
> is
> the winning strategy for voters, it boils down fast to approval
voting,
> which is not much better than plurality voting.
--Approval voting seems to be quite comparatively good if all the
voters are tactical.
In particular, if all voters are tactical then plurality, IRV, and
Condorcet systems all
are EFFECTIVELY THE SAME (i.e. all elect the same winner) in
scenarios where
there are 2 major-party candidates plus also some minor party
candidates whom the voters believe have little chance to win. That
is, more precisely, if the voters
always rank one major top and the other bottom (tactically) then a
major will always win in these voting systems, and a minor can never
win. Over time this effect causes the
minor parties to die and we get 2-party domination.
And game theory enters here. With some Condorcet dishonest voting
gives unnoticeable advantage to the voter. With range vote it does
much, and eventhe ballot leaves more room for it. Plurality even
punishes honest voting. So voters with nearly anything but Condorcet
will reduce the entropy of the ballot by tactical voting, and lead
the system to two party system. Because the winning strategy in a
two party system strengthens it.
This needs more careful thought:
In Plurality with majors expected to win, only those voting for a
major get counted in deciding on winner - others might as well not vote.
With Condorcet, and even Range, voters can apply full effort to the
duel between majors whether they do or do not expect such to win. At
the same time, they can vote for third parties, with this effort
measurable and having potential to win if strong enough.
IRV, with luck and the same voting, can do like Condorcet; with bad
luck can horrify.
Dave Ketchum
> From an information science perspective it is clear that a
preferential
> ballot have more information than an approval ballot.
--and range ballots still more.
Not, if you count the effect of tactical voting: range ballot
effectively becomes an approval ballot.
> Why do we discuss it in private anyway?
--OK with me if you post this email.
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