At 05:41 AM 1/21/2009, Kristofer Munsterhjelm wrote:
My usual argument against Approval (in favor of something more complex) is this: Say there are three viable parties (if there will be only two, why have Approval in the first place?). You support A > B > C. If A is in the lead, you can approve of A alone. If A's a minor party, then you should approve of both A and B. But if the parties are close, then it may not be clear who you should approve - if A's slightly too low (and the important contest is A vs C), then voting only A will split the vote and may cause C to be elected instead of B. If A's not that low (and the important contest is A vs B), then voting both A and B will cancel your vote for A with your vote for B. It becomes more difficult the closer the parties are in support, and polling errors could cause further problems.
Approval works within a multiple election environment, classically it wasn't used with anything other than a true majority requirement, and it was probably expected that initial votes would be bullet votes. Approval as a deterministic method that must find a winner with a single ballot is simply a more sophisticated, improved form of Plurality, as is IRV, but Approval is far simpler.
The scenario described is unusual in partisan elections, but I certainly wouldn't propose Approval as an ideal election method. It is merely the largest improvement that can be accomplished with such a minimal shift from Plurality: just start to count all the votes. Dump the no-overvoting rules.
With a majority requirement, Approval gets much better. Then we'd want to look at runoff conditions. Approval should *ameliorate* -- not entirely eliminate -- Center Squeeze. Approval theorists have largely failed to anticipate, I think, the degree of bullet voting that will occur. In Bucklin, which is Approval with some degree of Later No Harm protection (not absolute by any means), bullet voting was seen with most voters. But most voters, by definition, support frontrunners! I prefer Bucklin for public elections because it remains simple to canvass, resembles Approval in some good ways, and still allows voters to express an exclusive first preference. I'd allow multiple voting in all ranks, so a three-rank Bucklin ballot could be quite expressive. (Traditional Bucklin, as in Duluth, Minnesota, only allowed multiple votes in the third rank.)
Polling errors are mostly moot. Most voters don't vote based on polls, they vote based on their own impressions of their community. Voting systems theorists obsess about "strategy." Voters don't, generally. If sophisticated strategy is used, it's organized by people who supposedly know what they are doing, and it's questionable how much it's followed. Some will follow voter information cards. Some won't.
Optimal strategy in Range, for example, is only slightly better than a "sincere vote," i.e., one where preference strengths are accurately expressed. Actually, in the simplified situations I examined, "approval style voting" in Range was *the same* in expectation as "range style voting," with an intermediate candidate voted at an intermediate rating. However, *the variation* was greater: the "sincere vote" was more stable or conservative; the bullet vote was more effective in getting the best of what the voter wanted, but more at risk of getting the worst instead (by failing to vote for the compromise).
My suspicion, unproven, is that an accurate vote in Range is *generally* the best strategy, zero-knowledge. At the other extreme, where the voter knows the frontrunners accurately (and, totally extreme, the voter knows all the other votes and knows if the voter's vote could affect the outcome, and, if so, the voter votes to accomplish the best possible result), a bullet vote is just as effective as anything else.
Voters shouldn't have to do this.
We should make it easy for voters? Why? Is it a simple task to negotiate the winner? And that's what voters are doing. It gets really compressed into a single ballot, but most deliberative bodies don't work that way, and a majority is required to make a decision. Approval works really well in this environment, I've seen it.
Basically, know what you want, it's very clear, bullet vote. Could happily accept more than one candidate, vote for the ones you would happily accept. Unclear on which it is? Lean toward the bullet vote, if there is majority failure, you can modify your later vote. But whenever you have trouble deciding which of two candidates to vote for, vote for both!
What's hard about that? What's hard is when a majority is not required.
Since we know Plurality is bad, and IRV is bad as well (in one sense, it has to be, so it elects the "right" first candidate in a multiwinner election), that leaves Condorcet - or something exotic like MDDA.
I don't think I understand this statement. Range is the ideal single-winner election method that doesn't allow a runoff with majority failure. And it's simple to canvass. Of course, the simplest Range method is Approval.
There is a meaning to Condorcet failure, but not having preference strength information is a severe problem; and any method which considers preference strength for other than resolving Condorcet cycles is clearly flawed and can make preposterous choices. Yes, the Condorcet winner can be a preposterous choice, and would *lose* in a runoff. The only reason we think otherwise is that we imagine fixed preferences and a fixed electorate that votes according to these fixed preferences in the runoff, without considering the results of the first ballot. In real deliberative bodies, people respect preference strength and will yield first preference when the strength of it is weak. What goes around comes around.
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