[EM] Russ, Criteria that mention preference

[MIKE OSSIPOFF]

Russ said:

What we have here, it seems to me, is confusion cause by a failure to
distinguish between two fundamentally different classes of criteria.
Consider the basic voting process. It starts with the voters' true
preferences, then the votes are cast, then the votes are tallied and the
winner is determined:

true preferences --> votes cast --> winner determined

Let's call the process represented by the first arrow the "voting
strategy" and the process represented by the second the "tally rules."

I reply:

It's always been common knowledge on EM that strategy and count rules are 2 
separate topics.

Russ continued:

All voting system criteria that I have ever seen, excluding those that
originated with Mike, involve the tally rules. They consider only the
votes cast and make no reference whatsoever to the true preferences of
the voters.

I reply:

Perhaps. So what?

Russ continues:

At some point Mike came along and changed the paradigm fundamentally,
probably without ever explaining that he was doing so.

I reply:

The fact that my criteria mention preferences was obvious enough without 
explaining. The difference between my criteria and the traditional ones was 
much trumpeted by Markus and Blake, so it was well-known on EM.

Russ continues:

Naturally, this
causes confusion. To minimize the confusion, I suggest we distinguish
between "normal" criteria and "Mike-style" criteria.

I reply:

I'll call them traditional criteria and preference criteria.

Russ continues:

I'll get to the value of Mike-style criteria shortly, but first let me
say something about the old "Technical Evaluation" page at
ElectionMethods.org. It had a set of 8 or 9 criteria and a compliance
table for several major election methods.

Some of those criteria were Mike-style criteria and some were normal
criteria. However, looking back at it, I see that we had the Condorcet
criteria defined in terms of true preferences, with the stipulation that
the voters voted "sincerely." Stipulating that the voters vote sincerely
simply eliminates the voting strategy and essentially converts a
Mike-style criterion to a normal criterion.

I reply:

No, the Condorcet's Criterion that was at the website at the technical 
evaluation page was a Mike style criterioni entirely. It referred to the CW 
(which you called the IDW, defined as I define the CW), and it stipulated 
sincere voting. Both the CW and sincere voting are defined by me in terms of 
preference, and were defined at your website in terms of preference.

Russ continues:

But it involves an
unnecessary step that only confuses the matter. In other words, we had a
normal criterion bollocksed up to make it look superficially like a
Mike-style criterion.

I reply:

No, that Condoret's Criterion was thoroughly a Mike style criterion, for the 
reasons stated above.

Russ continues:

Mike-style criteria involve a model that normal criteria don't need.

I reply:

That's a safe statement, since traditional no-preference criteria don't need 
to mention preferences.

Russ continues:

They [Mike style criteria] need a model of voter preferences.

I reply:

Actually no. I've just told why they don't need a definition of preference, 
and they don't need the meaning of preference to be known, and they don't 
even need for preference to mean anything (though of course preference does 
mean something).

Russ continues:

What, then, is the value of Mike-style criteria? Voting strategy is a
very important topic, of course, but I think that Mike just confuses the
issue by trying to turn it into pass/fail criteria.

I reply:

Pass/Fail criteria are widely used in discussion of voting systems. They're 
the way to say something precise about voting systems.

Russ continues:

Take SFC, the "Strategy-Free Criterion":

"If an Ideal Democratic Winner (IDW) exists, and if a majority
prefers the IDW to another candidate, then the other candidate should
not win if that majority votes sincerely and no other voter falsifies
any preferences."

I reply:

That's your wording, corrected by me so that it retains the meaning that I 
intended. But let me state it my way:

If no one falsifies a preference, and if a majority prefer the CW to 
candidate Y, and vote sincerely, then Y shouldn't win.

[end of SFC definition]

Russ continues:

(IDW was my name for the "sincere" Condorcet winner.) The only complying
method is (a good variation of) Condorcet.

I reply:

The only well-known methods that comply with SFC are wv Condorcet methods.

Russ continues:

Now, what does this
Mike-style criterion tell us? It tells us that a majority can use a
strategy to thwart a minority.

I reply:

We're finding out that Russ hadn't a clue about the meaning of the criteria 
that were at his website.

Provided that no one falsifies a preference,
B loses without the CW>B voters doing other than voting sincerely. I don't 
call that a use of strategy by the CW>B voters. The point of the criterion 
is that, with complying methods, under the criterion's premise conditions, 
that majority needn't do other than vote sincerely, to make Y lose.

Russ continues:

So why, then, is it called the
"Strategy-Free" criterion? It is called that because the strategy
doesn't require any reversal of true preferences. But it *does* involve
insincere truncation strategy

I reply:

Not at all. Russ just stated the criterion, and it didn't say that the  
members of that majority could keep Y from winning if that majority 
truncated. It said that if no one falsifies a preference, and if the 
majority who prefer the CW to Y vote sincerely, then Y won't win, with a 
complying method. The CW>Y voters needn't do other than rank sincerely. 
That's why it's called the Strategy-Free criterion.

Russ continues:

, which the criterion itself does not
state. So the criterion name itself is misleading.

I replyi:

Russ has mislead himself by being unable to read what he's just copied.

Russ continues:

A more useful criterion is the normal (as opposed to Mike-style)
criterion taken from Blake Cretney's website:

Name: Secret Preferences Criterion: SPC
Application: Ranked ballots
Definition:
If alternative X wins, and some of the ballots are modified in their
rankings below X, X must still win.

I reply:

Useful for what? As I always point out, it depends on what one wants from a 
voting system. My criteria measure for the goal of  minimizing need for 
defensive strategy. Maybe Secret Preferences Criterion is useful for 
something else. Fine. Go for it. My criteria are explicitly written in terms 
of defensive strategy need. I don't claim that they should be useful to you 
if minimizing defensive strategy need isn't a goal of yours.

Russ continues:

Condorcet does not pass this criterion, which tells us that voters have
incentive to truncate in some cases if not routinely. OK, then, lets
determine when and how the voter should truncate rather than waste time
making a useless criterion out of it.

I reply:

...but SFC & GSFC describe conditions under which, with complying methods, 
certain voters don't need truncation, or any other strategy, in order to 
defeat a candidate.

Russ continues:

Oh, by the way, did I mention that Mike-style criteria are pedantic?

I reply:

Maybe, by pedantic, Russ means that they have precise meaning, which tends 
to be lost when Russ tries to rewordl them.

Mike Ossipoff

_________________________________________________________________
Express yourself instantly with MSN Messenger! Download today - it's FREE! 
http://messenger.msn.click-url.com/go/onm00200471ave/direct/01/