Hi Michael, On Thu, May 09, 2013 at 04:11:58PM -0400, Michael Ossipoff wrote: > [quote] > However this seems quite a risky strategy by the B voters. The > situation seems contrived and unlikely to arise in practice. > [/quote] > But what if the B voters know for a fact that the A voters are > completely conscientious, responsible, and co-operative, and that the > A voters are sure to rank B over C? > Sure, I agree that there are a number of good reaons why the chicken > dilemma needn't be a problem. But, even if it isn't a full-fledged > problem, it remains a _nuisance_. For me to consider this a nuisance, I would have to see that there is a practical case where a rational group of voters might use this strategy to sway the election in their direction. Clearly, there are cases where CSSD would reward strategic voting *if* a voting bloc had perfect knowledge of how everyone else would vote. But is that realistic? In your original scenario, the preferences are: 99: A>B>>C 2: B>A>>C 100: C>>(A=B) But how are the B voters to know this with certainty? Even one voter preferring A>C>B (or at least, voting that way) is sufficient to undermine this strategy, because instead of stealing the vote for B, they're suddenly throwing the vote to C, which is the outcome they strongly want to avoid: 98: A>B 1: A>C>B 2: B 100: C C defeats A, 100>99; A defeats B, 99>2; C defeats B, 101>100; so C is the winner. The reason we care about these properties of voting systems is that we want to avoid rewarding strategic voting. I posit that a strategy that allows for a margin of error of <1% in the attackers' understanding of how all other voters will vote before it yields a pathological outcome instead is not a very rewarding strategy at all. All other things being equal, it would of course be better to address the chicken dilemma. However, you bear the burden of demonstrating that all other things actually are equal. The method you propose has been evaluated with respect to a couple of important criteria (the Mutual Majority Criterion and the Condorcet Criterion); but what about other criteria that CSSD satisfies? There are lots of criteria that are interesting to students of voting, and it's well known that some of them are mutually exclusive; before making any changes to our voting system, we should understand the consequences fully, not just with regards to a couple of handpicked criteria that are superficially the most important. Where can we find public, third-party review and analysis of the method you propose (which seems to be a hybrid of other methods - so I'm not sure if it can properly be called "Schwartz Woodall" or not?)? Since the voting algorithm is enshrined in the Debian constitution, the cost of changing it is high; the burden of proof when arguing for a change is therefore high as well. Cheers, -- Steve Langasek Give me a lever long enough and a Free OS Debian Developer to set it on, and I can move the world. Ubuntu Developer http://www.debian.org/ slangasek@ubuntu.com vorlon@debian.org
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