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I'm not at all a fan of G-S and the Arrow Theorem, since they make widely unrealistic assumptions about voting (e.g. Arrow's IIA is nonsense - intensity matters

by yyyk 7y ago

I'm not at all a fan of G-S and the Arrow Theorem, since they make widely unrealistic assumptions about voting (e.g. Arrow's IIA is nonsense - intensity matters!). G-S and Arrow damaged tremendously any attempt to look at electoral systems rationally by imposing a mathematical description which is simply irrelevant to actual concerns. In your given example, the particular unrealistic assumption is the way it looks at voting. Voting is not an extended opinion poll. It is use of political power where each voter is given an equal amount. Therefore, there's no need to reduce "tactical voting" to a minimum (the useful requirements are far laxer than that). The voters in your example did not "fail" or "cheat" by voting for a candidate they liked less. They compromised, and therefore got a better result for them. Arguably a voting system that pushes people into consensus and majority is actually desirable and not a flaw. Aside, I do prefer Borda or Approval over IRV, but the better reasoning is just they are far simpler overall while preserving the actually important advantages.

roenxi 7y ago
Indeed. I'd be in favour of people who know Arrow's Theorum designing the voting system; but not because I care about tactical voting. I rank the voting systems [Anarchy] -> [Dictatorship] -> [First Past the Post] -> [IRV] -> [Approval]. Anarchy is sort-of the base case. Dictatorship is better than anarchy because at least it is large-scale organisation and infrastructure might happen. FPTP is that and the dictatorship can't be truly unpopular (<35% general support). IRV adds in a really stabilising ability for 3rd parties to successfully build support with a slow rolling campaign - makes it really hard for major parties to move away from the centre because people have a powerful signal for what they want. Approval adds in a level of simplicity to IRV. I like IRV for the same arguable reason you like tactical voting - a good system should really be a bit random in tight situations. 50.1% of the votes isn't really different from 49.9% and voting systems don't need to differentiate. In Australia (IRV) when we had our last really tight election a bloke got elected on a couple of hundred primary votes from the Australian Motoring Enthusiast party. His platform was basically that he liked souped-up fast cars. Nobody had ever heard of him. Dude was an excellent Senator, he read the legislation and thought about things. Big win for Australia, IMO. Better than some political swamp-creature elected on a tiny margin. Also; my favourite voting link: http://zesty.ca/voting/sim/ http://zesty.ca/voting/sim/ EDIT I think the order is obvious, but I upgraded my '>' to '->' for tmporter.
- tmporter 7y ago
  Your ranking list can be interpreted in two very different ways depending on whether you consider ">" to be an arrow or a greater-than sign.
- yyyk 7y ago
  In addition to the simplicity issue, IRV can have a practical problem of legitimacy, when the elected official is everyone's 10th choice (I exaggerate for effect). There are some arguments for allowing that, but I think the argument against is stronger - officials need legitimacy to serve effectively, otherwise we have a period of political instability which will end badly, and 10th choices won't practically have legitimacy. In Approval voting the preference order is a bit hidden so this doesn't happen. One of those cases where treating an election as if it's not an opinion poll at all is the better choice.
  - roenxi 7y ago
    If the preferences have run off to 10th place; the first 9 choices are controversial enough they wouldn't have legitimacy either. Look at America - the president has so gained so much legitimacy from FPTP that the House is trying to eject him from office. Voting system doesn't help with that much. That is an argument like the Chinese claiming democracy wouldn't work because China is different. In theory it can't be instantly debunked, but in practice it seems to be a non-issue (compared to alternatives) when IRV is tried.
    - yyyk 7y ago
      What's happening in America is not due to the election result, not anymore. That has more to do with the President's... temperament, and some very particular circumstances. If it was just FPTP where he won more electors but less votes, he would have been seen as legitimate by now, just like Bush was.
      - mncolinlee 7y ago
        I disagree. Polling in 2016 clearly showed Trump and Clinton were each individually the two least-liked nominees in their parties in modern presidential history. First-past-the-post and bitter primaries were largely responsible for the result-- over a third of voters remained at home on Election Day 2016. In some electoral systems, they even have an option to reject all nominees in these kinds of situations.
jlebar 7y ago
> Arrow's IIA is nonsense - intensity matters! Independence of irrelevant alternatives (IIA) says that adding another option shouldn't change a voter's (or the election result's) relative preferences among all other options. "The table's waiter comes by and says their desert options are blueberry pie and vanilla ice cream. You order the pie. Then the waiter comes back and says, we also have chocolate cake. 'In that case, I'll have the ice cream!'" I don't see what this has to do with intensity? Arrow's theorem does assume that intensity doesn't matter, but this isn't IIA but is rather the unnamed predicate that voters express their preferences by ranking candidates with no ties allowed, rather than an approval voting scheme, or a "on a scale of 1-10" scheme.
- yyyk 7y ago
  Your example only looks irrational when one looks only at the overall preference list and furthermore thinks that the only important result is the winner. i.e. when looking at elections as an extended opinion poll and applying a purely mathematical logic ignoring politics, just like the Arrow Theorem does. If a voter went for chocolate cake despite polls showing that this may cause blueberry pie to lose the election, maybe the voter does not care that much for blueberry pie over vanilla ice cream, or the voter really really cares for cake far more than the other choice - both of these are intensity issues and the election method de facto taking them into account is not irrational. Maybe the cake was the only nut free option, and some voters deciding for the cake despite not having nut allergy themselves and despite losing convince the restaurant to offer more nut free foods later. 99% of the 'irrelevant choice' cases actually have some political logic like the above behind them which Arrow theorem just blithely ignores. The 1% are usually some attempt to mislead the voters (say by running a hopeless candidate with a similar name to another in order to siphon off votes), and should be handled by the electoral commission.

by yyyk 7y ago

roenxi 7y ago

Indeed. I'd be in favour of people who know Arrow's Theorum designing the voting system; but not because I care about tactical voting. I rank the voting systems [Anarchy] -> [Dictatorship] -> [First Past the Post] -> [IRV] -> [Approval]. Anarchy is sort-of the base case. Dictatorship is better than anarchy because at least it is large-scale organisation and infrastructure might happen. FPTP is that and the dictatorship can't be truly unpopular (<35% general support). IRV adds in a really stabilising ability for 3rd parties to successfully build support with a slow rolling campaign - makes it really hard for major parties to move away from the centre because people have a powerful signal for what they want. Approval adds in a level of simplicity to IRV. I like IRV for the same arguable reason you like tactical voting - a good system should really be a bit random in tight situations. 50.1% of the votes isn't really different from 49.9% and voting systems don't need to differentiate. In Australia (IRV) when we had our last really tight election a bloke got elected on a couple of hundred primary votes from the Australian Motoring Enthusiast party. His platform was basically that he liked souped-up fast cars. Nobody had ever heard of him. Dude was an excellent Senator, he read the legislation and thought about things. Big win for Australia, IMO. Better than some political swamp-creature elected on a tiny margin. Also; my favourite voting link: http://zesty.ca/voting/sim/ http://zesty.ca/voting/sim/ EDIT I think the order is obvious, but I upgraded my '>' to '->' for tmporter.

tmporter 7y ago
Your ranking list can be interpreted in two very different ways depending on whether you consider ">" to be an arrow or a greater-than sign.
yyyk 7y ago
In addition to the simplicity issue, IRV can have a practical problem of legitimacy, when the elected official is everyone's 10th choice (I exaggerate for effect). There are some arguments for allowing that, but I think the argument against is stronger - officials need legitimacy to serve effectively, otherwise we have a period of political instability which will end badly, and 10th choices won't practically have legitimacy. In Approval voting the preference order is a bit hidden so this doesn't happen. One of those cases where treating an election as if it's not an opinion poll at all is the better choice.
- roenxi 7y ago
  If the preferences have run off to 10th place; the first 9 choices are controversial enough they wouldn't have legitimacy either. Look at America - the president has so gained so much legitimacy from FPTP that the House is trying to eject him from office. Voting system doesn't help with that much. That is an argument like the Chinese claiming democracy wouldn't work because China is different. In theory it can't be instantly debunked, but in practice it seems to be a non-issue (compared to alternatives) when IRV is tried.
  - yyyk 7y ago
    What's happening in America is not due to the election result, not anymore. That has more to do with the President's... temperament, and some very particular circumstances. If it was just FPTP where he won more electors but less votes, he would have been seen as legitimate by now, just like Bush was.
    - mncolinlee 7y ago
      I disagree. Polling in 2016 clearly showed Trump and Clinton were each individually the two least-liked nominees in their parties in modern presidential history. First-past-the-post and bitter primaries were largely responsible for the result-- over a third of voters remained at home on Election Day 2016. In some electoral systems, they even have an option to reject all nominees in these kinds of situations.

jlebar 7y ago

> Arrow's IIA is nonsense - intensity matters! Independence of irrelevant alternatives (IIA) says that adding another option shouldn't change a voter's (or the election result's) relative preferences among all other options. "The table's waiter comes by and says their desert options are blueberry pie and vanilla ice cream. You order the pie. Then the waiter comes back and says, we also have chocolate cake. 'In that case, I'll have the ice cream!'" I don't see what this has to do with intensity? Arrow's theorem does assume that intensity doesn't matter, but this isn't IIA but is rather the unnamed predicate that voters express their preferences by ranking candidates with no ties allowed, rather than an approval voting scheme, or a "on a scale of 1-10" scheme.

yyyk 7y ago
Your example only looks irrational when one looks only at the overall preference list and furthermore thinks that the only important result is the winner. i.e. when looking at elections as an extended opinion poll and applying a purely mathematical logic ignoring politics, just like the Arrow Theorem does. If a voter went for chocolate cake despite polls showing that this may cause blueberry pie to lose the election, maybe the voter does not care that much for blueberry pie over vanilla ice cream, or the voter really really cares for cake far more than the other choice - both of these are intensity issues and the election method de facto taking them into account is not irrational. Maybe the cake was the only nut free option, and some voters deciding for the cake despite not having nut allergy themselves and despite losing convince the restaurant to offer more nut free foods later. 99% of the 'irrelevant choice' cases actually have some political logic like the above behind them which Arrow theorem just blithely ignores. The 1% are usually some attempt to mislead the voters (say by running a hopeless candidate with a similar name to another in order to siphon off votes), and should be handled by the electoral commission.