[EM] Condorcet strategy and anti-strategy measures

[Adam Tarr]

This particular debate about strategy (a strategy Mike calls "offensive 
order-reversal") comes up periodically.  James's solution is innovative, 
but I don't think it's needed.

James Green-Armytage wrote:

>         I do believe that Condorcet wv had a serious strategy problem.

This problem is in no way limited to winning votes Condorcet.  The exact 
same strategy works in margins Condorcet.  Furthermore (and, in my opinion, 
more importantly), the same effect can often be achieved in margins 
Condorcet by simply truncating your ballot.  Simple truncation can only 
very rarely help your cause in winning votes condorcet, but it can help in 
common situations in margins Condorcet.

>         While it is unknown how likely a successful execution of the burial
>strategy would be in a public election, I believe that if it did occur, it
>would produce an *extremely* negative reaction towards both the result and
>the election method itself.

I agree, however, I see it as extremely unlikely that burial strategy would 
be successful on a large scale without public coordination, which would be 
easy to counter and would create a big scandal.

Remember that there are lots of people who have a sense of obligation that 
pushes them towards voting sincerely.

>         Is an example just like this very likely? No, I guess it's probably
>pretty unlikely. (However, I think that there are other kinds of examples
>where successful burying strategies are a bit easier and more plausible...
>I think that I've provided some of these examples already...) But anyway
>it is *possible*, and the possibility of such a disaster justifies at
>least one more balloting.
>         And yes, Mike, I *do* think that just one more balloting in the 
> event of
>a majority rule cycle would be a great help.
>         Let me put it this way: Without a second balloting, I would not
>necessarily feel comfortable about recommending Condorcet for public
>elections instead of something like IRV.
>         Not because IRV is a good election method (it isn't, really), or 
> because
>the Condorcet principle is unimportant (I think that it's extremely
>important), but because a successful burial strategy or an out-of-control
>chicken game in single-balloting Condorcet would just undermine the
>democratic process too severely, and I wouldn't feel comfortable in
>opening up the possibility for that.

No such chicken game exists.  If this strategy is pursued, there are 
successful potential counter-strategies that do not produce worse outcomes 
for the voters that take them.  In your example, the Nader voters can rank 
Nader and Kerry equally.  Given the large sincere Bush>Nader majority that 
is unaffected by the burial strategy, this costs them nothing.

>         With a second balloting, I would say that Condorcet is vastly 
> superior to
>IRV and pretty much any other public election method around.

What if no candidate is willing to drop out?

>         The thing is, the people who would be employing the 
> "countermeasure" will
>not know whether the strategy they are attempting to counter has taken
>place, until after the election!

As I said before, in my opinion, for this strategy to work it would have to 
be very public.

>And of course, at that point, it's very much too late to change whether or
>not you truncated.
>         As you know, there are various examples where if voters truncate 
> against
>a strategic threat that in fact does not exist to begin with, it can
>result in the election of the car crash candidate in itself.

Not in any example you've provided.  As I said, the Nader=Kerry>Bush vote 
is basically a freebie.

>So voters
>can't always take lightly the decision to truncate against a candidate who
>may or may not be supported by strategic buryers.

You need to provide an example where this is true.

>         What it may come down to is: To what extent do voters on each 
> side have a
>propensity to gamble with burial strategies? To what extent do voters on
>each side expect voters on the other side to engage in burial strategies.

You need to provide an example where this is true.

>         I think that in a two-round procedure, candidate withdrawal would 
> play a
>more important role in effectively neutralizing strategy. The best way to
>assure that no abuses would be effective in the second round would be for
>a set of candidates to come to some sort of agreement whereby all but one
>of them drop out of the race before the second balloting, so that the
>opposition would not be able to use one of them to 'impale' the other one
>with a huge artificial defeat and leave the legitimate defeat of their own
>candidate as the defeat of least magnitude. There is still plenty of
>opportunity for cooperation to break down during the negotiation stage
>here, but at least it isn't possible for a strategic maneuver to steal the
>election completely by surprise, as it is in the single-balloting version.

Again, what if nobody wants to drop out?  Or what if a new burial strategy 
emerges in the second round?  I don't see the 2-round election as a 
reliable solution to this "problem".

-Adam