I wasn't going to disagree with anything Russ posted, because I didn't want to seem to be picking on him, or argumentative. But, after a few of his postings, I finally decided that any posting that says misleading things can fairly and properly be commented on.
Russ said:
Like plurality, IRV tends to reach a stable equilibrium with two dominant parties.
I comment:
With Plurality, nearly any 2 parties can keep remaining the two top votegetters at Myerson-Weber equilibrium. MW equilibrium is only defined for point systems such as Plurality Approval, CR, & Borda, but it's also true that IRV, lilke Plurality, would tend to stably protect the perceived top-two, as Plurality does.
Russ continued:
Approval, on the other hand, will not necessarily reach a stable equilibrium with only two dominant parties.
I comment:
?With Approval, if there's a party that's always voter-median or CW, there will be a stable equilibrium with _one_ party--the CW or voter median party.
ERuss continued:
If I understand it correctly, it could allow any number of parties to reach a stable state of parity.
I reply:
The party that is always CW or at the voter-median would keep winning at MW equilibrium. Just that one party.
But it's true that Approval would fairly deal with any number of parties. But it wouldn't include them all in a winning equilibrium, nor should it.
Russ continued:
But I see a potential problem. If several parties reach parity, strategic voting becomes difficult, and the voter could end up with very difficult decisions. Do Greens approve the Democrat as a hedge against the Republican, or do they not? It's the same old problem, except now it's much more complicated.
I comment:
Same old problem, yes. It can be summarized by saying that Approval has strategy to a greater extent than Condorcet does. That's the difference between Approval & Condorcet.
"Except that now it's much more complicated": Much more complicated than what? Than Plurality? It isn't much more complicated, and in fact it isn't more complicated at all, to vote for the candidate that you'd vote for in Plurality and also for those whom you like better, as opposed to just voting in a Plurality election.
Russ continued:
Now Greens may need to worry about letting the Libertarian get elected if they don't vote for the Democrat.
I comment:
Again, this is nothing other than a re-statement of Approval's strategy situiation, as it's always been discussed here.
I and some others have very recently posted here about strategies for Approval. These strategies are ways of deciding the question that you're asking. They're ways of dealing with the strategy situation that you describe, the strategy situation that has always characterized Approval voting.
Russ continued:
As a matter of fact, they may need to think about approving the *Republican* to prevent the *Libertartian* from getting elected! Or vice versa.
I comment:
Actually, a genuine libertarian isn't worse than a Republican. A genuine libertarian is the opposite of a Republican on authoritarian issues. But that's a genuine libertarian, as opposed to an authoritarian.
Russ continued:
The bottom line is that the election could be tipped in any of several different directions depending on where voters decide to "draw the line" between their approved and disapproved candidates.
I comment:
Check the recent EM messages. There's been discussion about that very question: Where to draw the line in Approval.
Russ continued:
Maybe this is obvious, but I wonder how many have really thought about the potential consequences.
I comment:
Well,we've pretty much been discussing it quite a bit.
Russ continued:
I am not claiming that the disadvantages of Approval outweigh the advantages; I'm merely pointing out the potential problems.
I comment:
Condorcet has advantages over Approval, and many, for good reason, prefer Condorcet to Approval.
Approval has advantages over Condorcet, including some merit advantages over Condorcet.
Approval also has disadvantages in its comparison with IRV. They have already been pointed out, and much discussed on EM. Of course discuss them more if you want to , but they've already been pointed out. Or, of course, point out new ones.
Russ continued:
The Approval strategy "formulas" that have been put forth are interesting, but in many cases they will be of no practical use to voters. Why? Because they are based on how other voters are expected to vote, which is obviously uncertain. The best strategic cutoff point could depend critically on that uncertain information, in which case the formulas will be useless as a practical guide for voters.
I comment:
Hardly. The fact that some Approval strategies are based on estimates of who will likely be the top-2 votegetters, or on other probabilities (as opposed to certainties) doesn't lessen its usefulness as a practical guide for voters. Some Approval strategies require more to be estimated than others do. Some require different things to be estimated. Check the recent postings about Approval strategy.
Some ways of voting in Approval don't require probabilities to be estimated. Those too are discussed in recent EM postings.
It's obvious that if we only adopt for puiblic elections methods which have been tested by use in public elections, we're pretty much stuck with what is currently used in public elections. That's fine if you like what's currently in use.
Anyone arguing that Approval or CR might be worse than the Plurality currently in use would have to explain why Approval's or CR's added freedoms, freedoms that they add to what's allowed in Plurality, would make them worse than Plurality.
Mike Ossipoff
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