And whenever someone submitted a definition for WDSC, SDSC or FBC in terms of cast preferences and asked you whether his definition corresponds with your intention of this criterion, you always refused to answer.
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."
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.
At some point Mike came along and changed the paradigm fundamentally, probably without ever explaining that he was doing so. Naturally, this causes confusion. To minimize the confusion, I suggest we distinguish between "normal" criteria and "Mike-style" criteria.
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. 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. Now that Mike is out of the picture, such embarrassments have been eliminated. If and when I ever post a new webpage on criteria, it will have none of that crap.
Mike-style criteria involve a model that normal criteria don't need. They need a model of voter preferences. I had stated on the "Technical Evaluation" page that we assume each voter has a sincere personal preference list, a sincere ranking of the candidates (that may or may not be truncated). That seems reasonable to me. Another model could be a sincere cardinal (numerical) rating of the candidates, but that would be a more specific model.
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.
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."
(IDW was my name for the "sincere" Condorcet winner.) The only complying method is (a good variation of) Condorcet. Now, what does this Mike-style criterion tell us? It tells us that a majority can use a strategy to thwart a minority. 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, which the criterion itself does not state. So the criterion name itself is misleading.
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.
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. Could it be that good voting strategy in Condorcet involves truncation at the Approval cutoff point? Now *that* would be interesting.
Oh, by the way, did I mention that Mike-style criteria are pedantic?
--Russ
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