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What would you say to someone like me who feels that IRV is perhaps the worst possible alternative voting system to advocate for? It feels like someone at some

What would you say to someone like me who feels that IRV is perhaps the worst possible alternative voting system to advocate for? It feels like someone at some stage must be very dishonest, or otherwise dangerously uninformed, to think that IRV is worth advocating for over alternatives like approval voting, range voting, or any Condorcet voting system. I'm very worried that most places will have the political will to improve the voting system only once in a century and we'll have wasted it on a system that's unusually ill-behaved. I'm particularly concerned about IRV's non-monotonicity, whereby it's possible to hurt a candidate by ranking them higher, and likewise it's possible to help a candidate by ranking them lower. How can anyone feel they're voting honestly in an honest election when this is the case?

throw5away 5y ago
Honestly IRV is _even worse than plurality_. It doesn't solve the problems it sets out to solve (it entrenches two-party domination [1]), it has ridiculous monotonicity violations [2], all for a lot more complication in counting the votes (you can't distribute the counting well without transmitting the contents of all of the ballots) and possibly wrecking the secret ballot (you can encode and buy specific down-ballot rankings). Seriously, it's all of the disadvantages and very limited upside. [1] https://rangevoting.org/TarrIrvSumm.html https://rangevoting.org/TarrIrvSumm.html [2] http://zesty.ca/voting/sim/ http://zesty.ca/voting/sim/
- deleted 5y ago
  [deleted]
- zestyping 5y ago
  And worse: it suppresses the Black vote, as if we didn't have enough of that already. https://rangevoting.org/SPRates.html https://rangevoting.org/SPRates.html https://www.yes2repeal.org/spoiled-ballots https://www.yes2repeal.org/spoiled-ballots IRV means much higher rates of spoiled ballots, disproportionately in low-income neighbourhoods. It's actively harmful.
- wslack 5y ago
  > you can't distribute the counting well without transmitting the contents of all of the ballots There are only so many combinations of rankings that are possible. It shouldn't be hard to encode each of those possible orders and transmit them as a whole.
  - godelski 5y ago
    > There are only so many combinations of rankings that are possible. O(n^2) isn't great though... The algorithm to count is rough and requires many rounds (since you count, knock out the lowest candidate, recount, and repeat until a >50% favor is achieved by one candidate). Cardinal systems on the other hand just require summing the columns and taking argmax. This is far simpler (in fact we can do most of this in parallel making a far better runtime).
  - zestyping 5y ago
    "Only so many" = At least N factorial. If ties are allowed, then even more. With 20 candidates in an election, that's over 2 billion billion possibilities. It's not practical.
klodolph 5y ago
Two reasons: Arrow’s impossibility theorem and the fact that people are not perfect logicians. I honestly thought that after learning Arrow’s impossibility theorem that Condorcet is not especially important. Since we can’t have a perfect voting system, we have to pick an imperfect one, and among the alternatives, it’s important to capture information from voters. Instant runoff captures a lot of information. Approval voting I think is much too tactical and, strictly speaking, worse than IRV. No contest. IRV lets people express their preferences in a fairly understandable way. The strategy I see people talking about is “rank all the front-runners, and use the leftover spots to rank the people you want to win, even if they’re not likely to win.” So if A B C and D are front-runners, and E and F are the two other candidates you like, you come up with a ranking for those six and put the top five on your ballot. The idea that people who like this system are “dangerously misinformed” or “dishonest” is needlessly inflammatory.
- godelski 5y ago
  > Arrow’s impossibility theorem First off, Arrow's doesn't apply to all systems. You'll need to look into both Gibbard's and Gibbard-Satterthwaite's theorems. Second off, just because you can't find a global optimization in a highly dimensional space doesn't mean there aren't local optimizations along criteria we care more about. Appealing to Arrow's is a cop-out. > Approval voting I think is much too tactical and, strictly speaking, worse than IRV. No contest. You're going to have to back this up with some strong evidence. Approval has higher VSE, is simpler, is more resistant to spoilers and tactical voting. > IRV lets people express their preferences in a fairly understandable way. Actually your argument holds true for any ordinal or cardinal system. Cardinal even having more flexibility since you can give two candidates the same score. And in cardinal if you want to rank your candidates, no problem. Better yet, you have better encoding opportunities because you can specify the distance between your ranking instead of the uniform spacing that ordinal systems force upon you. (BTW, given what the person above you wrote, I would assume that they know how ranked voting works and explaining how it is going to come off as you calling them dumb).
  - klodolph 5y ago
    I disagree that cardinal voting is understandable. It’s how we rate restaurants and review products on Amazon, and I don’t think it translates to an election with multiple options. The issue here is not just how logical humans “homo economicus” behaves, but how actual voters behave. Not really interested in engaging with the rest of this comment right now, but suffice it to say that I don’t think you’re accounting for human behavior in practice, which is messy and illogical. I don’t think it’s reasonable to say that I’m appealing to Arrow’s impossibility theorem as a cop-out—I’m saying that since we don’t have a game theoretic solution the the problem, we should look at the actual behavior of imperfect, irrational humans as the deciding factor.
caf 5y ago
The non-monotonicity tactical voting possibility is overblown: it only really works in the toy "which is the favourite pizza of these 30 students" examples. In real world elections, the conditions where it is even theoretically possible arise only rarely (A > B > C with three choices, but B > A and A > C with two choices, and A's lead over B significantly greater than B's lead over C in the three choice scenario, and A's lead over C in the two choice scenario more than twice B's lead over C in the three choice scenario) and more importantly, they're not predictable enough beforehand. Advocating this kind of tactical vote stands at least as much chance of hurting your candidate as helping them, so nobody does it. When you analyse real-world large scale IRV elections, you find that cases where the IRV winner isn't the Condorcet winner are rare, and this balances against the very real benefit of having a counting method that is easy to explain and understand.
- godelski 5y ago
  The non-monotonicity is actually pretty important and we have real world examples of this. Clay mentions the Alaska race in this comment[0]. We've seen this issue in Southern states that used this to disadvantage black voters. This is also the reason Bernie would spoil Biden (and vise versa). So I'm not sure what you're getting at. [0] https://news.ycombinator.com/item?id=27598975 https://news.ycombinator.com/item?id=27598975
  - caf 5y ago
    Let's look at the "Bernie would spoil Biden" example. The idea is that the Republicans endorse only one candidate, Trump, and the Democrats endorse two: Bernie and Biden. In the non-tactical voting case, the second-last round votes shake out like: Trump 45 Biden 28 Bernie 27 Bernie is eliminated, the votes in his pile split 24 / 3 between Biden and Trump (a preference flow of 89% to Biden) and the final round of counting ends up: Biden 52% Trump 48% ..but tactical voting intervenes! A small number of Trump voters (2% of the total electorate) are organised to tactically switch their votes to 1. Bernie 2. Trump, resulting in a second-last round of: Trump 43 Bernie 29 Biden 28 Now Biden is eliminated, the votes in his pile split 20 / 8 Bernie/Trump (a weaker preference flow of 71% to Bernie, because of Biden voters too conservative to vote for Bernie) and the final round is now: Trump 51 Bernie 49 Tactical voting has won the day! However, this really illustrates the problems here for the prospective tactical voter: 1. They need pretty perfect information to pull this off. Not just on first round votes, but on how the preferences are going to flow as well. If those Biden votes flowed a little weaker to Trump, all they'd have done is elect Bernie instead; if Trump had been a little stronger overall than they expected in the no-tactical-voting, their tactical voting attempt might have backfired completely and turned a fair Trump win into a loss! Opinion polling just isn't this precise. 2. They have a co-ordination problem. If they switch too few votes, the scheme fails and they just elect Biden with a greater margin than before; too many and the scheme fails and they elect Bernie, a candidate they're presumably less happy with actually getting the Presidency than Biden. 3. All of this only works if the balls line up perfectly in the first place, even setting aside the problem already mentioned of how you know the balls are going to line up. If the second-last round votes are instead Trump 45 / Biden 30 / Bernie 25 then the Bernie to Biden preference flow has to fall under 66% for the scheme to be possible. Rather than trying to engage in this dubious and risky tactical voting attempt, the Trump campaign would be far better served just spending their resources trying to turn out more of their voters. After all, the theoretical possibility only exists when the margins are tight in the first place. A tangential matter is that even in an IRV election it still probably makes sense for the parties to either endorse only a single candidate each - otherwise their candidates will waste some of their resources attacking their co-party candidate when they could have launched them against their main opposition - or at least mutually agree to distribute campaigning material advising to give a second preference to their co-party candidate (a so-called "preference swap" arrangement).

throw5away 5y ago

Honestly IRV is _even worse than plurality_. It doesn't solve the problems it sets out to solve (it entrenches two-party domination [1]), it has ridiculous monotonicity violations [2], all for a lot more complication in counting the votes (you can't distribute the counting well without transmitting the contents of all of the ballots) and possibly wrecking the secret ballot (you can encode and buy specific down-ballot rankings). Seriously, it's all of the disadvantages and very limited upside. [1] https://rangevoting.org/TarrIrvSumm.html https://rangevoting.org/TarrIrvSumm.html [2] http://zesty.ca/voting/sim/ http://zesty.ca/voting/sim/

deleted 5y ago
[deleted]
zestyping 5y ago
And worse: it suppresses the Black vote, as if we didn't have enough of that already. https://rangevoting.org/SPRates.html https://rangevoting.org/SPRates.html https://www.yes2repeal.org/spoiled-ballots https://www.yes2repeal.org/spoiled-ballots IRV means much higher rates of spoiled ballots, disproportionately in low-income neighbourhoods. It's actively harmful.
wslack 5y ago
> you can't distribute the counting well without transmitting the contents of all of the ballots There are only so many combinations of rankings that are possible. It shouldn't be hard to encode each of those possible orders and transmit them as a whole.
- godelski 5y ago
  > There are only so many combinations of rankings that are possible. O(n^2) isn't great though... The algorithm to count is rough and requires many rounds (since you count, knock out the lowest candidate, recount, and repeat until a >50% favor is achieved by one candidate). Cardinal systems on the other hand just require summing the columns and taking argmax. This is far simpler (in fact we can do most of this in parallel making a far better runtime).
- zestyping 5y ago
  "Only so many" = At least N factorial. If ties are allowed, then even more. With 20 candidates in an election, that's over 2 billion billion possibilities. It's not practical.

klodolph 5y ago

Two reasons: Arrow’s impossibility theorem and the fact that people are not perfect logicians. I honestly thought that after learning Arrow’s impossibility theorem that Condorcet is not especially important. Since we can’t have a perfect voting system, we have to pick an imperfect one, and among the alternatives, it’s important to capture information from voters. Instant runoff captures a lot of information. Approval voting I think is much too tactical and, strictly speaking, worse than IRV. No contest. IRV lets people express their preferences in a fairly understandable way. The strategy I see people talking about is “rank all the front-runners, and use the leftover spots to rank the people you want to win, even if they’re not likely to win.” So if A B C and D are front-runners, and E and F are the two other candidates you like, you come up with a ranking for those six and put the top five on your ballot. The idea that people who like this system are “dangerously misinformed” or “dishonest” is needlessly inflammatory.

godelski 5y ago
> Arrow’s impossibility theorem First off, Arrow's doesn't apply to all systems. You'll need to look into both Gibbard's and Gibbard-Satterthwaite's theorems. Second off, just because you can't find a global optimization in a highly dimensional space doesn't mean there aren't local optimizations along criteria we care more about. Appealing to Arrow's is a cop-out. > Approval voting I think is much too tactical and, strictly speaking, worse than IRV. No contest. You're going to have to back this up with some strong evidence. Approval has higher VSE, is simpler, is more resistant to spoilers and tactical voting. > IRV lets people express their preferences in a fairly understandable way. Actually your argument holds true for any ordinal or cardinal system. Cardinal even having more flexibility since you can give two candidates the same score. And in cardinal if you want to rank your candidates, no problem. Better yet, you have better encoding opportunities because you can specify the distance between your ranking instead of the uniform spacing that ordinal systems force upon you. (BTW, given what the person above you wrote, I would assume that they know how ranked voting works and explaining how it is going to come off as you calling them dumb).
- klodolph 5y ago
  I disagree that cardinal voting is understandable. It’s how we rate restaurants and review products on Amazon, and I don’t think it translates to an election with multiple options. The issue here is not just how logical humans “homo economicus” behaves, but how actual voters behave. Not really interested in engaging with the rest of this comment right now, but suffice it to say that I don’t think you’re accounting for human behavior in practice, which is messy and illogical. I don’t think it’s reasonable to say that I’m appealing to Arrow’s impossibility theorem as a cop-out—I’m saying that since we don’t have a game theoretic solution the the problem, we should look at the actual behavior of imperfect, irrational humans as the deciding factor.

caf 5y ago

The non-monotonicity tactical voting possibility is overblown: it only really works in the toy "which is the favourite pizza of these 30 students" examples. In real world elections, the conditions where it is even theoretically possible arise only rarely (A > B > C with three choices, but B > A and A > C with two choices, and A's lead over B significantly greater than B's lead over C in the three choice scenario, and A's lead over C in the two choice scenario more than twice B's lead over C in the three choice scenario) and more importantly, they're not predictable enough beforehand. Advocating this kind of tactical vote stands at least as much chance of hurting your candidate as helping them, so nobody does it. When you analyse real-world large scale IRV elections, you find that cases where the IRV winner isn't the Condorcet winner are rare, and this balances against the very real benefit of having a counting method that is easy to explain and understand.

godelski 5y ago
The non-monotonicity is actually pretty important and we have real world examples of this. Clay mentions the Alaska race in this comment[0]. We've seen this issue in Southern states that used this to disadvantage black voters. This is also the reason Bernie would spoil Biden (and vise versa). So I'm not sure what you're getting at. [0] https://news.ycombinator.com/item?id=27598975 https://news.ycombinator.com/item?id=27598975
- caf 5y ago
  Let's look at the "Bernie would spoil Biden" example. The idea is that the Republicans endorse only one candidate, Trump, and the Democrats endorse two: Bernie and Biden. In the non-tactical voting case, the second-last round votes shake out like: Trump 45 Biden 28 Bernie 27 Bernie is eliminated, the votes in his pile split 24 / 3 between Biden and Trump (a preference flow of 89% to Biden) and the final round of counting ends up: Biden 52% Trump 48% ..but tactical voting intervenes! A small number of Trump voters (2% of the total electorate) are organised to tactically switch their votes to 1. Bernie 2. Trump, resulting in a second-last round of: Trump 43 Bernie 29 Biden 28 Now Biden is eliminated, the votes in his pile split 20 / 8 Bernie/Trump (a weaker preference flow of 71% to Bernie, because of Biden voters too conservative to vote for Bernie) and the final round is now: Trump 51 Bernie 49 Tactical voting has won the day! However, this really illustrates the problems here for the prospective tactical voter: 1. They need pretty perfect information to pull this off. Not just on first round votes, but on how the preferences are going to flow as well. If those Biden votes flowed a little weaker to Trump, all they'd have done is elect Bernie instead; if Trump had been a little stronger overall than they expected in the no-tactical-voting, their tactical voting attempt might have backfired completely and turned a fair Trump win into a loss! Opinion polling just isn't this precise. 2. They have a co-ordination problem. If they switch too few votes, the scheme fails and they just elect Biden with a greater margin than before; too many and the scheme fails and they elect Bernie, a candidate they're presumably less happy with actually getting the Presidency than Biden. 3. All of this only works if the balls line up perfectly in the first place, even setting aside the problem already mentioned of how you know the balls are going to line up. If the second-last round votes are instead Trump 45 / Biden 30 / Bernie 25 then the Bernie to Biden preference flow has to fall under 66% for the scheme to be possible. Rather than trying to engage in this dubious and risky tactical voting attempt, the Trump campaign would be far better served just spending their resources trying to turn out more of their voters. After all, the theoretical possibility only exists when the margins are tight in the first place. A tangential matter is that even in an IRV election it still probably makes sense for the parties to either endorse only a single candidate each - otherwise their candidates will waste some of their resources attacking their co-party candidate when they could have launched them against their main opposition - or at least mutually agree to distribute campaigning material advising to give a second preference to their co-party candidate (a so-called "preference swap" arrangement).