[EM] voting methods

[Árpád Magosányi]

I guess the list might have opininons in this discussion.

2009/6/4 Warren Smith <warren.wds at gmail.com>

> > 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.

> 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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