Arrow's Theorem (2014)

Re:Arrow's Theorem (2014) by domador on Friday November 10, 2017 @10:06PM (#15674777)

It sounds appealing, but I wonder if in practice range voting tends to collapse into first-past-the-post, with people voting tactically to maximize the chances of a popular candidate winning (instead of voting for the candidate they most prefer). This is why systems such as optional preferential voting appeal to me despite their (different) flaws. I wonder if monotonicity and trying to avoid circular electoral preferences are slightly overrated goals. I suspect that a good electoral system might involve a bit of satisficing, of producing great outcomes even when the theoretically best outcome isn't consistently achieved.

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Re:Arrow's Theorem (2014) by OscarCunningham on Saturday November 11, 2017 @03:45AM (#15675541)

In fact it collapses into aproval voting, which is like range voting except every score is 0 or 1, or equivalenty like FPTP except that you can vote for more than one person.

But it turns out that approval voting is itself considered a very good voting system (I remember reading an article about how a conference of experts voted on their favourite voting systems and approval voting won, but I can't find it because "voting system vote" isn't a very good Google search).

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Re:Arrow's Theorem (2014) by baddox on Saturday November 11, 2017 @06:32AM (#15675923)

I think The main theoretical problem with most approval and range voting methods is that they fail the Condorcet and majority criteria. A candidate who is preferred over every other candidate by a majority of voters can lose, which sucks, but in practice it is debatable how common such an occurrence would be.

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Re:Arrow's Theorem (2014) by sampo on Friday November 10, 2017 @10:27PM (#15674849)

> I wonder if in practice range voting tends to collapse into first-past-the-post

Of course it will. The fundamental problem is selecting only one representative per voting district. However fancy and complicated voting algorithm you make, it will most probably collapse anyway. It's the size of the voting districts that leads to a two-party system, not the voting mechanics.

But then: Just pool nearest 20 voting districts [x] into one large voting district, from which you elect 20 representatives, and any kind of simple proportional voting mechanics [xx] will do. If you elect 20 representatives, any party that manages to get at least 5% of the voes will get their representative to the Parliament. New political parties start to appear, and a multi-party system emerges on its own.

[x] Or 15, or 30 or whatever.

[xx] Such as the D'Hondt method, https://en.wikipedia.org/wiki/D%27Hondt_method

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Re:Arrow's Theorem (2014) by baddox on Saturday November 11, 2017 @06:41AM (#15675953)

It’s hard for me to imagine that the actual outcome of such a proportional representative system would be worse (in my judgment) than the current US federal district system, but the theoretical criticisms are obvious. For instance, it makes sense to have representatives represent a specific area who were supported by a majority of voters from that area. That way, the representative can in theory represent specific interests that are disproportionately important to citizens from that specific area (e.g. agricultural issues for rural areas or public transportation issues for urban areas).

Of course, drawing these districts (in either system) is an inherently arbitrary process which can lead to counterintuive or obviously unideal results, the most obvious example of which being gerrymandering. But at the end of the day, unless we have a one world democracy, borders must be drawn. National borders are “easy” in the sense that they tend to be formed not by a democratic political process but rather historical conflict.

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Re:Arrow's Theorem (2014) by straightarrow on Friday November 10, 2017 @10:29PM (#15674856)

" people voting tactically to maximize the chances of a popular candidate winning (instead of voting for the candidate they most prefer)"

I'm not sure I understand your comment. There is no "instead" -- you can vote honestly for both your preferred candidate and the popular candidate.

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