[EM] Kristofer, re; ICT and Approval, part 1

Tue Apr 24 13:56:53 PDT 2012

**
Kristofer:

I'm going to improve my answers to this post.

You wrote:

But I'm pretty sure that ICT fails clone independence. Clearly CT does...

[endquote]

Some criteria compliances must be given up for others. I consider FBC and
defection-resistance to be the important considerations, because they both
address serious strategy problems that, by greatly distorting voters'
expression,
also greatly distort and worsen society itself.

You continue:

You've also said that ICT fails the Plurality criterion

[endquote]

I said that some months ago, and then, when Chris Benham (introducer of ICT)
pointed out that ICT _doesn't_ fail the Plurality Criterion, I
admitted that I was
mistaken, and had mis-understood the definition of ICT.

You continued:

You've also said it
elects C in Kevin's MMPO example.

[endquote]

The answer to that is the same as above: I made that statement in the
same posting
in which I said that ICT fails the Plurality Criterion. When Chris
pointed out that
those statements were incorrect, I admitted it, and explained that I'd
made those two
statements because I'd misunderstood the definition of ICT.

ICT is as I've defined it in recent postings. According to Chris
Benham, ICT does not
fail the Plurality Criterion, and does not elect C in Kevin's MMPO bad-example.

You continued:

You don't consider that important, but
you've said that it could cause real trouble for ICT's proposability.

[endquote]

I no longer say that, because I now realize that ICT does not have
those two problems.

You continued:

I'd also *think* that ICT fails Condorcet loser, but I don't know that
for sure. The proof would set up a system where ICT's analogous Smith
set differs considerably from the real Smith set, so that the Plurality
winner within the analogous Smith set is the Condorcet loser in practice.

[endquote]

As I said, we must choose which criteria we consider important, and be
willing to
give up the others. Every criterion sounds compelling. But some criteria address
serious, important strategy problems, as I said above.

You continued;

On a side note, now that I remember, I think the FBC you're talking
about is not the strong FBC (which almost no method passes)

[endquote]

Approval passes Strong FBC.

Can anyone show that any other method passes that criterion?

, but the
ordinary FBC.

{endquote]

Yes, the FBC I've been referring to all this time, and what I mean
when I say "FBC" without qualification,
is the weakest version we've discussed. We can also call that "Weak FBC".

Condorcet, Kemeny and IRV all fail Weak FBC, the most lenient and
least demanding version of FBC.

Approval meets Strong FBC, and might be the only method that does.

You continued:

If so, then that doesn't mean that betrayal doesn't pay
off. It simply means that for all situations where betrayal could pay
off, there also exists some other strategy that gives the voter the same
amount of (or more) strategic additional power. And if that's the FBC
you're talking about, then it doesn't mean nobody benefits from favorite
betrayal, and the actual degree of protection would depend on how simple
the non-betrayal strategy is.

[endquote]

Yes, but all of the methods that I've called FBC-complying _do_ have a
very simple and easy
non-betrayal strategy. I've described it in Intermediate FBC and
Intermediate FBC-2, both of which
are passed by all of the methods that I've called FBC-complying. It's
a stronger, more demanding,
less lenient criterion than FBC (Weak FBC).

I'm referring to the Intermediate FBC and Intermediate FBC-2 that i
posted today, rather than to the ones
that I posted last night.

The non-betraying protective strategy that I describe in Intermediate
FBC is always available and successful
in the methods that I've been calling FBC-complying.

You saked:

 Does ICT pass the strong FBC?

I don't know.

Maybe Approval is the only method that passes Strong FBC.

Can anyone name a method other than Approval that passes Strong FBC?

**
>* Approval's strategies are simple. Condorcetists and IRVists are missing*>* that.*
Yes, "frontrunner plus" is pretty simple.

[endquote]

So are the other Approval strategies.

Frontrunner-plus is a special case of the better-than-expectation strategy,
Approval's general strategy.

However, it also adds another
component to the game: the polling loop. The voters need feedback to
know where to put the threshold (or they can guess, which will give them
less power if they're wrong).

[endquote]

Don't blame Approval. Blame Gibbard & Satterthwaite. What you said
above is true of
all nonprobabilistic methods.

When the election is neither u/a nor zero-info, strategy for _all_
nonprobabilistsic
methods is based on some sort of information, assessment, or feel
about the outcome.
That can hardly be presented as a uniquely proprietary fault of Approval.

It's just a universal fact about voting system strategy.

You continued:

That feedback then should be rolled into
the next iteration of polling, to which the voters react *again*, and
the polling adjusts, until equilibrium.

[endquote]

...true of all nonprobabilistic methods.

 Simple? Perhaps, but I can't help but feel it's a hassle.

[endquote]

I'm sorry you feel that way about voting, but all nonprobabilistic methods
are like that in elections that are not u/a and not 0-info.

You continued:

And if the
feedback goes just a little wrong, the method will fail precisely when
it's needed the most: with candidates of similar strength.

[endquote]

That suggests a question about what you mean by "wrong". When you vote according
to your best information, or your best feel expectation for the
election, there's nothing
"wrong" with that voting. It is understood that, in a non-0-info
election, we don't have perfect
information.

I shuffle a deck of cards, and set the deck down. I look at the top
card, without letting you see it.
I ask you what is he probability that the top card is the ace of spades. To you,
that probability is 1/52. To me, that probability is 0, because I saw
that the top card is the 3 of clubs.
But you aren't wrong. Based on the information that you possess,
the probability that the top card on he deck is the ace of spades _is_ 1/52.
*do those things count for when people are engaging in these strategies?:*
>* 1. Condorcet, like Approval, is not defection-resistant. Lack of*>* defection-resistance is Approval's only actual problem. In other*>* words, Condorcet retains Approval's only problem worth mentioning.*>* The defection problem can be dealt with perfectly well in Approval,*>* in (at least) the five ways that I listed and described in a previous*>* post. It can probably be similarly dealt with in Condorcet. The point*>* is that Condorcet shared Approval's problem. Rank balloting doesn't*>* get rid of it.*
It is if more people are honest.

[endquote]

deBorda said, "My method is for honest men." Are you saying the same
thing about Condorcet?

But I don't know that defection is about dishonesty. Even the ethical
and co-operative
A voters, in the Approval bad-example, have incentive to defect (and
public announce it), if it
will show the B votes that their defection can only backfire.

You continued:

If voters want to be honest in
Approval, what choice do they have?

[endquote]

What do you call an honest vote, or a dishonest vote in Approval?

Using strategy is not dishonest. Not in Approval, and not in Range. It
_is_ dishonest in Range
if it is undestood that everyone is going to rate in a way sincerely
intended to indicate
their preference-intensities as accurately as possible.

You continued:

Should they take dice to the polls
so that they can probabilistically emulate Range?

[endquote]

Honesty certainly doesn't require that voters in Approval emulate
another method,
such as Range.

You continued:

True, if everybody decides to bury or truncate to get as much as they
can, to the effect you get a sort of internal Approval election, then
there will be an unstable tipping point like in Approval.

[endquote]

As I said, Condorcet fully possesses Approval's biggest problem, the
co-operation/defection
problem, also known as the "chicken dilemma".

You continued:

On the other
hand, if that's not the case, then Condorcet can glean more information
from the rank ballots than from Approval's one-or-nil ballots.

[endquote]

Not denied. But you can't assure us that there won't be significant
favorite-burial in Condorcet, as I detailed in one of my posts yesterday.

You continued:

(And in Burlington-style elections where there's an n-way contest but
it's not too close, ranked voters under good systems can give their
actual preference. Yet in Approval they'd be unsure without polling data
- at least I would.)

[endquote]

I wouldn't. If you're saying that it's a 0-info election, then:

If there are no unacceptable candidates who could win, then approve
the above-mean candidates,
the candidates whose merit, for you, is above-mean.

If there are unacceptable candidates who could win, then it's a u/a
election Approval's strategy
in a u/a election is the simplest there is: Approve all of the
acceptables, and none of the unacceptables.

No question about how to vote in that 0-info election.

When the election is neither 0-info nor u/a, there are other suggestions.

All of the above voting instructions can be found in my Approval article.

But what you're saying is that if you know that everyone will rank
sincerely (a very big "if"),
in Condorcet, then you also know that you can rank sincerely, and in
that particular special
case, your voting can be strategy-free--unless you want to make sure
that you fully want to
protect Compromise against Worse. In that case, you'll rank Compromise
alone in 1st place,
and lower Favorite to below 1st place.

I know what you're saying: You're saying that you want something more
than what Approval guarantees.
I'm telling you that you can't count on getting that with Condorcet.
I'm saying that the gain with
rank balloting is often or usually _illusory_.

I've admitted that there is a rank method that I'd like to have: ICT,
mainly for its defection-resistance.

So I don't criticize you for wanting more, from a rank method. I
merely advise you that the gain that you
want might or might not be available.

 >* 2. Favorite-burial due to FBC failure. I've talked a lot about why
FBC*>* will be a problem even in Condorcet. You argue on that matter
later,*>* below, and I answer your arguments there.  So, here, I'll
just ask, How*>* much do Condorcet's Criterion and the rankings' free
expressivity mean*>* when people are burying their favorites to
maximally help compromises?*
When everybody are burying, not a whole lot. When people are fully
honest, then there's no maximal burying.

I know I said this when I answered this post before, but if people
were really fully honest,
unselfish, interested primarily in the good to society, then Range
would be the best method.

When you say, "...if people ranked honestly, ...", realize that that
is a big "if".

You continued:

In between, the benefit is also
in between those edge cases. In the very worst case, people can do the
sort of countermeasures that you say can be done in Approval

[endquote]

Oh no: In the worse case, the situation is much worse than Approval,
because people are burying their favorites,
making nonsense out of the election.

 -- but they
don't need to care about them if they don't find themselves close to
that worst case (unlike Approval).

[endquote]

Approval doesn't encounter Condorcet's worst case.

>* 3. Offensive burial. With only 3 candidates, Condorcet well-deters*>* offensive burial. With more than 3 candidates, that deterrence pretty much*>* evaporates. I can find some losing candidate, someone who definitely*>* won't pair-beat mine, and my faction can make hir beat the sincere CW.*>* When that's being done, how much do Condorcet's Criterion and*>* expressivity mean?*
Eh? If there is no cycle, then you need a faction that's at least a
majority to make that losing candidate beat the sincere CW.

[endquote]

Even without my (and my faction's) strategy, there are already some
(probably sincere) pairwise votes for Loser against the Sincere CW.

Ok, Loser can't be too despised, or s/he wouldn't have many pairwise votes
against the SCW (Sincere CW).

You continued:

So someone
must have already established a cycle

[endquote]

My faction's offensive burial strategy makes a cycle, by adding its
pairwise votes
to the already-existing, probably sincere, pairwise votes for Loser
against the SCW.

You continued:

, and even then, your faction has
to outweigh the faction that voted according to their preference of the
sincere CW over the loser.
[endquote]

We don't have to do that alone. We have the help of those who
sincerely prefer Loser
to the SCW.

Contrary to what you said somewhere in these paragraphs, we do _not_
need to be a
majority.

 >* Besides, whether or not offensive burial is rampant, you can bet
that*>* opponents will make much of it. And they'll have a lot more
airtime*>* and print-space than you will. And remember that you can't
prove that*>* offensive burial will be rampant. You can say that you
think it won't be.*>* Opponents and media, etc., can continually
emphasize that no one knows*>* for sure, and that we'd be taking a
chance on a method with which*>* we don't know what would happn.*
So we let experience make our case. I'll talk about that later, but for
now, I'll just say that IRV, even with its 2.5 party problem, has been
tried in various places.

[endquote]

And repealed in Burlington. IRV, if my guess is right, was enacted here and
there, in a few municipalities around the country, by heavy
promotional spending.
In any case, IRV has no chance whatsoever of making it to the election
of officeholders
in national offices. But, for now, neither does any good reform method
other than Approval.

Ok, Range might have a chance, but it's more complicated, making it
much more vulnerable to
"This is going to need a lot more study."

You continued:

That problem is worse than offensive burial, in
my opinion, because IRV picks the wrong winner even when given mostly
honest ballots.

[endquote]

Yes,IRV would be worse than Condorcet, under existing electorate conditions.

To be continued...

Mike Ossipoff
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