5 ms·
> Where's the paradox? Exactly. I propose that the paradox is in first-past-the-post voting, a 5% swing leads to a 100% change in representation. How can that
by DougBTX 2y ago
> Where's the paradox?
Exactly. I propose that the paradox is in first-past-the-post voting, a 5% swing leads to a 100% change in representation. How can that be?
- gadders 2y agoRelax - they're all broken: https://www.investopedia.com/terms/a/arrows-impossibility-theorem.asp https://www.investopedia.com/terms/a/arrows-impossibility-th...
- evan_piermont 2y agoOnly if you reject the axiom of choice: https://www.jyotirmoy.net/posts/2013-10-28-arrow-ultrafilter.html https://www.jyotirmoy.net/posts/2013-10-28-arrow-ultrafilter...
- lupire 2y agoOnly if you have infinite voters.
- xigoi 2y agoArrow’s impossibility theorem only applies to ranked choice voting systems.
- cubefox 2y ago... which are almost never used in voting for governments.
- lupire 2y agoFPTP is a ranked choice system.
- cubefox 2y agoNo it isn't.
- xigoi 2y agohttps://en.m.wikipedia.org/wiki/Ranked_voting https://en.m.wikipedia.org/wiki/Ranked_voting > The most commonly-used example of a ranked-choice system is the familiar plurality voting rule, which gives one "point" (vote) to the candidate ranked first, and zero points to all others (making additional marks unnecessary).
- cubefox 2y agoThis is not what is usually meant with the term (plurality voting is different from ranked voting where there are non-trivial preference orderings) and in any case not what the Arrow theorem applies to.
- xigoi 2y agoArrow’s theorem defines a ranked voting system as a function that takes a permutation of the candidates for each voter and outputs a single permutation of the candidates. As a special case, if you take the function which sorts the candidates by how many voters ranked them as first, you get plurality voting.
- cubefox 2y agoAnd that makes plurality voting different from ranked voting where the voters can submit arbitrary preference orderings. In any case, as I said, the Arrow theorem doesn't apply to plurality voting, as there can be no cycles in the aggregate.
- gadders 2y agoYes, but what I mean is that even if you move away from FPTP voting, the others all have compromises.
- isotypic 2y agoBut for many the drawbacks of ranked choice systems are far more preferable to those of FPTP. Additionally, Arrow's theorem only states that the spoiler effect cannot be completely eliminated by ranked choice - it says nothing about how often such an event actually occurs, and in practice spoiler candidates will occur less frequently with ranked choice systems compared to FPTP. Additionally, rated choice voting systems are not subject to Arrow's theorem.