At 11:55 PM 2/11/2010, Dave Ketchum wrote:
We all get careless and stumble, sooner or later!But I choke on two details here: You misuse the label "plurality" - having only the ability to vote for 1 even though, for many races most intelligent voters will find there is only one candidate deserving approval. Even Approval has more power, letting voters vote for more than one, though unable to differentiate. Condorcet is another important step up, letting voters vote for more than one while indicating which they like best. Forcing voters to act as if they wanted to vote for more than they wish to is a step backward, and should not pretend to be an asset for a method.
I'm not following Mr. Ketchum's arguments here. But "plurality" was used in a very ordinary sense. Any method which elects without a vote of a majority of those who cast non-blank ballots in an election is an election by plurality, using the definitions of Robert's Rules (and of most parliamentary procedure manuals, I believe, if not all). There is room for interpretation on whether or not a non-blank ballot that does not contain a legal vote should be included in the basis for majority, but no room for excluding from the basis those who do cast a valid vote, but for a candidate that is, say, later eliminated due to low vote count.
Hence almost all voting systems that have been considered, absent vote coercion (as with mandatory full ranking or penalization of partial ranking, as happens with some versions of Borda Count), are "plurality methods," including Approval and Range and, the point here, Condorcet methods.
I did incorrectly state the case at first, by showing lower rankings that did add additional votes for other candidates by A. The example was clearer with all bullet votes. What this points out is that a ranking of, say, A>B>C>D>D>F>G>H is, from this point of view, a vote for G over H. Should this be considered an "approval" of G? The voter has expressed that, in an election between G and H, the voter would prefer H, though, in fact, in a deep ranking like that, this is probably noise for the most part. (Robson Rotation is, in fact, used to eliminate some of this noise by averaging it out so that, at least, it is not produced by ballot position.)
"Majority" is a word whose merits need more serious thought - see an earlier post from today. Ditto "runoffs".
Indeed. Voting systems theory, early on, focused on attempts to find the ideal single-ballot system, from various perspectives. While this is a theoretically interesting question, it essentially misled the entire field when applied to real election reform, ignoring the most widely used voting reform, top two runoff, as if it were merely a more expensive and cumbersome version of Sri Lankan Contingent vote. Or batch-elimination IRV, same thing. It isn't. It produces different results than IRV, in about one-third of runoffs in nonpartisan elections. (Probably in partisan elections, it produces roughly the same results.)
In addition, this approach ignored the *universally used* direct democratic method, repeated balloting, with no decision being made without a majority of those voting supporting it. None. No exceptions.
Ignoring explicit voter approval, then, is one of the widespread systemic errors. Another one, arising early on, was the assumption that pure preference profiles were adequate to understand how voting systems would amalgamate votes and produce a useful social ordering, when, in fact, any sane method of studying how voting systems work would realize that a strong preference is different from a weak or barely detectable one, not to mention an indistiguishable one that is forced by a voting system to be crammed into one of A>B or B>A, with no allowance for A=B. And real, human, social decision-making systems, outside of voting, do consider preference strength, very much.
And any system that attempts to maximize benefit to a society based on preference profiles would have to take preference strength into account. That it may be difficult to do this, that it may be difficult to determine commensurability, does not change this. What we can see through the device of assuming absolute utilities for voters in simulated elections is that the Condorcet Criterion and the Majority Criterion, for similar reasons, can require preposterous results, in situations where, with a single ballot and no other amalgamation method operating, will produce a result that will later, if it's tested, be *universally rejected.* I'd call that a Bad Decision. And any system which considers preference strength, that allows the expression of it and then uses that information for other than simply resolving a Condorcet cycle, *must* fail the Condorcet Criterion.
Originally, my assumption, as with many students of this field, was that the Condorcet Criterion was the King of Criteria. Well, the King has been dethroned. It's a good and useful criterion, it has a place. But applied rigidly, it is quite possibly harmful.
I've argued that if ballots show a Condorcet winner, an election should not resolve in favor of another candidate, except possibly in situations where a legitimate cause of Condorcet failure can clearly be identified and it can be known that voters would then reject the Condorcet winner, knowing the results of the first election. Other than that possibility, I would always want to see Condorcet failure submitted again to the voters for review and possible confirmation or rejection of the failure. Rejection of the failure would probably mean election of the Condorcet winner, and, as long as the voters can do this, it must be said that the *overall method* satisfies the Criterion. It only looks like it didn't by not immediately jumping for the Condorcet winner in a primary. The later ballot completely supercedes the former, which is totally standard democratic process.
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