Re: [EM] Ranked Preferences, example calculations

[Chris Benham]

Abd ul-Rahman Lomax wrote: At 06:09 AM 10/30/2006, Chris Benham wrote: Abd ul-Rahman Lomax wrote: The strongest preference is expressed in range by rating the undesired outcome at the minimum rating and the desired outcome at the maximum rating. If the majority does this, and if they are in agreement about these two things, they will prevail. "Strong preference" means strong preference for a desired outcome. If they only have a weak preference, and express such a preference, they might not get it. CB: This requires them to be coordinated regarding their "desired outcome". What if they agree that X should lose but are split about which individual candidate should get max. rating, or they agree that Y should win but are split about which candidate should get minimum rating? Why shouldn't they also "prevail" in those cases? Abd:Continually, it is assumed that the majority should "prevail," i.e, a small preference by a majority should prevail over a large preference of a minority, no matter how great the gap in preference, and no matter how close the minority is to the majority. His argument here applies equally well to Approval Voting, it is just that the matter is starker there, and does require strategic considerations on the part of the voter. I.e., under Approval, a voter must, to vote with full power, determine an approval cutoff which involves knowing who the top candidates are likely to be, and then the voter must effectively state that both of them are equally preferred. Now voters are interested in "voting with full power" are they? In that case of course Range also "requires strategic considerations on the part of the voter". Approval is a Range method with binary input. The majority should prevail when it is voting on a single question. Why is that?  There you go again, always assuming that the majority should prevail! If  a choice between Yes and No, is a "single question" then why isn't a choice between candidates A and B?   And if "the majority should prevail" in a choice between two candidates, why not between two factions of candidates? The Majority Criterion is sensible when it is a two-candidate election, and both sides are informed about the preference strengths of the other. Assuming that the voters consider the "preference strengths" of other voters to be an important issue. Venzke pointed out that this is what happens with pizza, which is why pizza choosers don't actually use Range. They do the Range work informally and then use a Supermajority criterion, Approval Style, unless nobody has a strong preference, in which case they will simply choose the favorite of the majority. But that informal process breaks down on a large scale. Kevin argues that it doesn't. There is enough public discussion and reporting of pre-polls that if voters like the pizza choosers still think that the consensus candidate should win, then can pretty easily guess who s/he is and simply voter for her/him. What "breaks down"  from the pizza choosing scenario is that the voters either don't care about the preference-strengths of other voters or they think  there are more important issues. A big difference in the pizza choosing scenario is that no-one thinks that anyone else's pizza preference is stupid or mistaken. Often in elections a group of voters Y want to over-ride the preferences of a rival group of  voters X not because they are hostile to X's real interests and welfare, but (at least in part) because they consider the X voters to be wrong about which candidate would best promote that if elected. The Majority Criterion is weak when considering elections with more than two candidates. To repeat, Chris, in his argument, continues to rely on the Majority Criterion. He is using the Majority criterion to justify the Majority Criterion. He is not deriving the Majority Criterion from generally accepted principles that do *not* include the Majority Criterion. No, I have shown that the absence of  majority-related guarantees (including the "Majority criterion") encourage dishonest voting by giving such voters more power to determine the result.  Maybe *not rewarding dishonesty* is  one  of  your "generally accepted principles". I'll quote again and answer directly: What if they agree that X should lose but are split about which individual candidate should get max. rating, or they agree that Y should win but are split about which candidate should get minimum rating? Why shouldn't they also "prevail" in those cases? They are split about the second-best. The question should be reversed. So if you can't answer my question, just change it to one you prefer. Now, question is, why not just choose the candidate with the most first-preference votes? I agree that the Schulze method is superior, but just making the Plurality choice satisfies the Plurality Criterion, which is broadly accepted, though, I think we would agree, it is accepted ignorantly. It is obvious that you don't know what the "Plurality criterion" is. http://wiki.electorama.com/wiki/Plurality_criterion It is met by almost every sensible method including Schulze and IRV, and also some others like Range and Approval. He expects that people would engage in a conspiracy to vote insincerely in order to impose their weak preference on the society. CB: What "conspiracy"? An agreement to vote insincerely. "Strategically." What "agreement"?  If a group of people all do the same thing, like get out of the rain, does that mean that there was an "agreement"?  "Agreement" and "conspiracy" implies that they conferred beforehand. And it *is* a control system we are engineering. The winner-take-all nature of preference election systems is quite dangerous, from an engineering perspective. Condorcet could make it worse, because the Condorcet winner in one election might be from fanatic party A, with 35% of the vote, and the next one from party B, with 35% of the vote.... The society swings. (And this is indeed what I think we are seeing in U.S. politics. We'll see. The percentages may be about right, if Condorcet were being used.) So according to Abd, "Condorcet could make it worse". What is "it" exactly?..the present system? Right off I'll note that these votes are preposterous. People will not vote, in such numbers, anything like this. CB: Completely irrelevant for my demonstration. But what Chris is demonstrating is that Range does not satisfy the Majority Criterion. No, I was demonstrating vulnerability to the Compromise strategy.  And  my example wasn't "preposterous". Well, I would have to assume that the serious closeness of this election would be known. A shift from 98 to 99 is hardly a major shift. CB: Sufficient to force those voters to stop expressing their B>A preference. Note how we have a situation where the "sincere preference" is 99 to 98 in Range. No you don't. You obviously didn't even read my not-very-long  message that you are replying to, or at least you reply to bits of it before you've read all of it. Chris expresses this situation as "forcing" voters to vote insincerely. But if they vote sincerely, with the initial conditions, they get a candidate who is almost perfect to them, relatively speaking. The difference is insignificant. So why are they "forced" to vote the extremes, to lie about their rating of their second choice? Where does this pressure come from? One of Abd's annoying habits is to falsely put words in my mouth. In none of my messages in this thread did I use the words "forcing", "forced" or even plain "force". What Chris is going to have to show, if he can, and he wants to use examples, is an example where social damage is done by selecting the Range winner over the Majority winner, in a pure Range system. What constitutes "social damage" is a big somewhat subjective and controversial topic (and arguably off-topic). I have in the past shown that Approval (and the demonstration would also apply to Range) is very vulnerable to  disinformation campaigns.  (But I'm sure that Abd would find my scenario "preposterous" and/or not a case of  "social damage"). I've recommended that Range elections include a facility for expressing Favorite *without* giving a higher rating. I've also recommended that Range be coarser, not 0 to 99, I'd rather see 0 to 10. CB: The fact that the range was so large (99-0) is what forced me to make the difference in size between the two factions so small. Yes. However, with a larger step size (i.e, 0.1 rather than 0.01, comparing Range 11 with Range 101), it is more likely that candidates would rate equally. The Favorite _expression_ option makes this less painful to partisans. A 10% difference in preference strength is probably still down in the noise in terms of what it means to human beings. It is still a slight preference. I agree from the perspective of the individual voter, a "Favourite _expression_ option" makes for an improvement, but with this having no force to influence the result it could make the winner look illegitimate. Now, note that I proposed, in these and concurrent threads, a safety feature, a runoff if the preference winner were different >from the Range winner. CB: Yes *you* did, but that isn't the CRV proposal. That's right. CRV has *not* in my opinion developed, yet, a consensus definition of Range, as far as the details are concerned. I have been addressing the pure Range method, not some as yet not even fully defined "Range with Runoff" or "Range with Ratification" scheme of yours. Yes. Note that these "schemes" would be normal in standard deliberative process. "Shall so-and-so take office" is a not uncommon motion. I'd insist on it, where I have the choice! In other words, the context of a method matters. A method which is vulnerable to some possible malfunction can actually be the optimal method if the context deals with that and prevents it from actually causing damage. Since all methods are arguably "vulnerable to some possible malfunction", philosophically I agree. Remember, the "sincere" vote here was A99>B98. CB: The ranking was sincere but as I explained, the ratings maybe not. We can't understand what the rankings actually mean if we do not know what the sincere ranking would actually be. We know the "sincere rankings" just not the "sincere ratings". There is nothing ambiguous about rankings. What Chris was allegedly examining was the vulnerability of Range to strategic voting. But we can't examine strategic voting unless we understand what sincere voting was. The first results, 99 to 98, were presumably in the absence of strategic considerations. No. We can do nothing other than assume that these are sincere. If the preference were stronger than that, why would the Range voters not want to express it? Because they can only do so by reducing the voted strength of their stronger B>C preference and thus increase the danger that C will win. The 18 B voters have "defected" from the AB coalition by insincerely changing from B99>A98 to B99>B0=C0, and Range rewards their dishonesty (and disloyalty) by electing B. Now, why would they do this? Only if they strongly prefer B to A. But this contradicts the initial conditions. CB: Range only allows voters to express one "strong" (by your definition) preference (between two candidates or two sets of equally-ranked candidates). . And yet we imagine that the B voters are going to lie about their preference, in cahoots with each other, in order to elect B? CB: Who (besides you) mentioned anything about them being "in cahoots with each other"? You did. You mentioned an agreement to vote in a certain way, as I recall. No coordination is needed. As long as the other factions vote the same way, individual members of the B faction can try the strategy without any risk of it back-firing (and it can work if only some of them do it.) Once again, the suggested behavior makes no sense. It has been constructed artificially just in order to show a characteristic of Range Voting that we all agree is true. It does not satisfy the Majority Criterion, and, further, a group of voters voting in highly coherent patterns can push an outcome the way they want. Yes, they can. However, the point I've been making is that this is essentially stupid behavior. CB:Like me reading and replying to Abd's posts. And there is no reason to suppose that, if Range Voting is implemented, such behavior will be common enough to significant affect outcomes, *plus* if it *does* affect outcomes, it seems that it does so in a way that is not offensive to the majority. The examples given all show election outcomes that are satisfactory to the majority. No they don't, for reasons I've explained. *Quite* satisfactory. So where is the beef? It is also at least possible that a majority believe in "majority rule", so the "beef" could be post-election intense. Chris  Benham

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