Difference between revisions of "Talk:1844: Voting Systems"

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Generally the idea behind Arrow's Theorem is that you would get different results if you did a vote where the choices were just A or B, B or C, C or A, thus no option wins head to head against the others (Condorset Paradox). An example I recently read was economic policy, and how the options being presented can cause policy to fluctuate wildly in a democracy as the outcome depends on the options compared. -- [[Special:Contributions/108.162.249.10|108.162.249.10]] 16:01, 31 May 2017 (UTC)
 
Generally the idea behind Arrow's Theorem is that you would get different results if you did a vote where the choices were just A or B, B or C, C or A, thus no option wins head to head against the others (Condorset Paradox). An example I recently read was economic policy, and how the options being presented can cause policy to fluctuate wildly in a democracy as the outcome depends on the options compared. -- [[Special:Contributions/108.162.249.10|108.162.249.10]] 16:01, 31 May 2017 (UTC)
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"Arrow's impossibility theorem states that when voters have three or more distinct alternatives (options), no ranked voting electoral system can convert the ranked preferences of individuals into a community-wide ranking."  Arrow's theorem does not say that.  Arrow's impossibility theorem says "When voters have three or more distinct alternatives (options), no ranked voting electoral system can convert the ranked preferences of individuals into a community-wide ranking that is <b>complete, transitive, Pareto efficient, have universal domain, has no dictator, and independent of irrelevant alternatives</b>."  The conditions matter, and the non-dictatorship condition in particular is horrible misnamed.[[Special:Contributions/162.158.62.21|162.158.62.21]] 18:05, 31 May 2017 (UTC)

Revision as of 18:05, 31 May 2017


Consolidate Information

Looks like 2 of us added explanations at the same time. Someone else want to consolidate them and produce a concise explanation?

~blackhat

I tried merging our explanations, so there is a small improvement, but there is still some duplicated information. Plus I'm not a native english speaker, so a consolidation by a third editor would be welcome.

Something I don't understand about the Arrow Impossibility Theorem: In the example given, the result of the election is obviously a 3-way tie, where each candidate got exactly equal support. Surely the Arrow Impossibility Theorem doesn't complain about voting system's inability to intuitively break an exact tie?


I think there is another layer of explanation here. When Cueball is discussing this - he's talking about voting for which voting system is to be chosen. The choice is Approval versus Instant Runoff - but isn't Cueball arguing about using a Condorcet method to decide WHICH voting method to choose? This is emphasised by the mouse-over text which talks about him dynamically changing his choice of ultimate candidate based on the election system chosen - which is exactly the Condorset paradox, but when applied to the selection of which voting system you want rather than the choice of candidate. Again reinforced by the discussion of "Strong Arrows theorem" which at that same meta-voting level. 162.158.69.39 15:40, 31 May 2017 (UTC)

Generally the idea behind Arrow's Theorem is that you would get different results if you did a vote where the choices were just A or B, B or C, C or A, thus no option wins head to head against the others (Condorset Paradox). An example I recently read was economic policy, and how the options being presented can cause policy to fluctuate wildly in a democracy as the outcome depends on the options compared. -- 108.162.249.10 16:01, 31 May 2017 (UTC)

"Arrow's impossibility theorem states that when voters have three or more distinct alternatives (options), no ranked voting electoral system can convert the ranked preferences of individuals into a community-wide ranking." Arrow's theorem does not say that. Arrow's impossibility theorem says "When voters have three or more distinct alternatives (options), no ranked voting electoral system can convert the ranked preferences of individuals into a community-wide ranking that is complete, transitive, Pareto efficient, have universal domain, has no dictator, and independent of irrelevant alternatives." The conditions matter, and the non-dictatorship condition in particular is horrible misnamed.162.158.62.21 18:05, 31 May 2017 (UTC)