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> RCV does have some serious problems. Eliminating the candidate with the least first-place votes at each round means a high probability of rejecting compromise

> RCV does have some serious problems. Eliminating the candidate with the least first-place votes at each round means a high probability of rejecting compromise candidates that may be a lot of voters' second choice. Also, placing your first-choice candidate first isn't always a safe choice. RCV is non-monotonic, which means it's possible that ranking someone first might actually cause them to lose. That's weird, and I think it's a good enough reason to investigate other options. This is actually not true and the opposite of what happens. With RCV, people feel comfortable putting compromise or 3rd party candidates first because they know they aren't throwing away a vote. It creates a system where there is more middle ground and less black and white 2 party systems.

zestyping 5y ago
With IRV, you can put a compromise or third-party candidate first _only if they have no chance_. In other words, it's purely symbolic. As soon as the third-party candidate starts to become competitive, the spoiler effect returns. It becomes risky to vote for your true favourite, and voters are forced to vote strategically as they do now. So IRV will not help us escape from polarized two-party politics; it will continue to entrench the duopoly. IRV has other serious problems with fairness (a much higher spoiled ballot rate, disproportionately in low-income areas), practical implementation (requiring a redesign of ballots and counting software), and security (it isn't summable, which makes it harder to conduct a risk-limiting audit). Approval is also imperfect, but it is simple, cheap, effective, and has none of these problems.
- openandshut 5y ago
  help me out here, I don't understand how the spoiler effect returns if the third party candidate becomes competitive. Wouldn't that just mean they have a chance of winning? Suppose Dave Chappelle ran in 2020 and 40% of people voted for him and they all had Biden ranked at #2. 15% rank Biden #1, and 45% rank Trump #1 with no #2 marked. Biden wins, no? edit: found your explainer elsewhere, currently reading. edit edit: Huh, that is weird.
  - elihu 5y ago
    That's a pretty good example, because it illustrates a disconnect between how people expect IRV/RCV to work and how it actually works. Biden would be eliminated first, because he had the fewest 1st choice votes in the first round. The Dave Chappelle voters' 2nd choices for Biden don't matter: they're thrown out because Biden was eliminated. So, it comes down to Chappelle with 40% and Trump with 45%. If none of the Biden voters listed Chappelle as their second choice, then Trump wins. If enough voters had Chappelle as their second choice, then Chappelle wins. The lesson from this example is: it's quite possible that your second choices don't matter, because they're eliminated too early. We could come up with other examples that show that it isn't always safe to put your first choice first, either. IRV/RCV is non-monotonic, which means in some cases you can cause a candidate to lose by ranking them higher.
elihu 5y ago
I agree with what /u/zestyping says in the other comment, so I won't repeat it. But here's a video explaining the strategic voting issue: https://www.youtube.com/watch?v=JtKAScORevQ https://www.youtube.com/watch?v=JtKAScORevQ Also, wikipedia has an example of a non-monotonic result here: https://en.wikipedia.org/wiki/Monotonicity_criterion#Instant-runoff_voting_and_the_two-round_system_are_not_monotonic https://en.wikipedia.org/wiki/Monotonicity_criterion#Instant...

zestyping 5y ago

With IRV, you can put a compromise or third-party candidate first _only if they have no chance_. In other words, it's purely symbolic. As soon as the third-party candidate starts to become competitive, the spoiler effect returns. It becomes risky to vote for your true favourite, and voters are forced to vote strategically as they do now. So IRV will not help us escape from polarized two-party politics; it will continue to entrench the duopoly. IRV has other serious problems with fairness (a much higher spoiled ballot rate, disproportionately in low-income areas), practical implementation (requiring a redesign of ballots and counting software), and security (it isn't summable, which makes it harder to conduct a risk-limiting audit). Approval is also imperfect, but it is simple, cheap, effective, and has none of these problems.

openandshut 5y ago
help me out here, I don't understand how the spoiler effect returns if the third party candidate becomes competitive. Wouldn't that just mean they have a chance of winning? Suppose Dave Chappelle ran in 2020 and 40% of people voted for him and they all had Biden ranked at #2. 15% rank Biden #1, and 45% rank Trump #1 with no #2 marked. Biden wins, no? edit: found your explainer elsewhere, currently reading. edit edit: Huh, that is weird.
- elihu 5y ago
  That's a pretty good example, because it illustrates a disconnect between how people expect IRV/RCV to work and how it actually works. Biden would be eliminated first, because he had the fewest 1st choice votes in the first round. The Dave Chappelle voters' 2nd choices for Biden don't matter: they're thrown out because Biden was eliminated. So, it comes down to Chappelle with 40% and Trump with 45%. If none of the Biden voters listed Chappelle as their second choice, then Trump wins. If enough voters had Chappelle as their second choice, then Chappelle wins. The lesson from this example is: it's quite possible that your second choices don't matter, because they're eliminated too early. We could come up with other examples that show that it isn't always safe to put your first choice first, either. IRV/RCV is non-monotonic, which means in some cases you can cause a candidate to lose by ranking them higher.

elihu 5y ago

I agree with what /u/zestyping says in the other comment, so I won't repeat it. But here's a video explaining the strategic voting issue: https://www.youtube.com/watch?v=JtKAScORevQ https://www.youtube.com/watch?v=JtKAScORevQ Also, wikipedia has an example of a non-monotonic result here: https://en.wikipedia.org/wiki/Monotonicity_criterion#Instant-runoff_voting_and_the_two-round_system_are_not_monotonic https://en.wikipedia.org/wiki/Monotonicity_criterion#Instant...