Comment by mindslight
1 day ago
Restating my disclaimer of "It's been a while since I've studied the details of voting systems"...
> ranked voting methods ... can fail IIA even with no strategy applied, just by changing an irrelevant alternative.
Can you clarify whether you're referring to some ranked methods (eg IRV), or all ranked methods (ie including ranked pairs) ?
> that's not under or oversold, it's just measured performance.
Isn't this due to defining "performance" in a way that is congruent with Approval (/ Score) ? A quick skim of that VSE page has it talking about "utility", which I would imagine is a scalar per candidate representing "happiness" ?
The problem I have with Approval is that coming from our two-terrible-party system - do I Approve my latent terrible party or not? That choice seems purely down to strategy, compared to being able to rank them to say I completely prefer the new party/candidate over my latent terrible party, and my latent terrible party over the other latent terrible party. The dynamic also seems exacerbated knowing there will be a lot of people who continue to vote exactly as they did under plurality.
it's mathematically proven that all ranked methods can fail IIA. see arrow's theorem.
> Isn't this due to defining "performance" in a way that is congruent with Approval (/ Score)
1. i did not define performance in a way that is congruent with approval/score. scores are not utilities. they are the modification of utilities via ignorance, normalization, and strategy.
2. that the correct social welfare function is just the sum of all voter utilities (the definition of "performance") is mathematically proven. https://www.rangevoting.org/UtilFoundns
> do I Approve my latent terrible party or not?
this is not a "problem". it's well understood. https://www.rangevoting.org/RVstrat6
approval voting obliterates IRV ("RCV") with any mixture of strategic or honest voters, so i'm not sure why you're bringing up strategy. https://www.rangevoting.org/StratHonMix