Chicken dilemma: Difference between revisions
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(Point out the relation between the chicken dilemma and the criterion named after it, and fix some grammar.) |
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The "chicken dilemma" refers to a situation where two similar candidates share a majority, but are opposed by one candidate which has a plurality against either of the two. This can happen when there is a majority split into two subfactions (below called A and B), competing against a united minority (below called C) that is bigger than either of the subfactions. |
The "chicken dilemma" refers to a situation where two similar candidates share a majority, but are opposed by one candidate which has a plurality against either of the two. This can happen when there is a majority split into two subfactions (below called A and B), competing against a united minority (below called C) that is bigger than either of the subfactions. |
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This scenario has been called the "chicken dilemma" because in many election systems, the two majority subfactions are in a situation that resembles the classic "[[W:Chicken (game)|chicken]]" or "snowdrift" game (especially if voters are not sure which of the two subfactions is larger). |
This scenario has been called the "chicken dilemma" because in many election systems, the two majority subfactions are in a situation that resembles the classic "[[W:Chicken (game)|chicken]]" or "snowdrift" game (especially if voters are not sure which of the two subfactions is larger). A method that encourages cooperation by threatening to punish defectors is said to pass the ''chicken dilemma criterion''. See Analysis for more information. |
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== Definition == |
== Definition == |
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Below are two definitions of Chicken Dilemma; "CD" and "CD2" |
Below are two definitions of the Chicken Dilemma criterion; "CD" and "CD2". |
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=== CD === |
=== CD === |
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CD is sufficient, as-is, but here is a non-numerical definition: |
CD is sufficient, as-is, but here is a non-numerical definition: |
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The A voters are the voters who vote A over everyone else. The B voters are |
The A voters are the voters who vote A over everyone else. The B voters are the voters who vote B over everyone else. The C voters are the voters who vote C over everyone else. |
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the voters who vote B over everyone else. The C voters are the voters |
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who vote C over everyone else. |
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'''Premise:''' |
'''Premise:''' |
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# Some voting systems, such as approval voting, ignore the problem. Perhaps the assumption here is that it will be impossible to organize a defection without prompting a retaliation, and thus that both sides will prefer to cooperate. ("Mutual assured destruction"?) |
# Some voting systems, such as approval voting, ignore the problem. Perhaps the assumption here is that it will be impossible to organize a defection without prompting a retaliation, and thus that both sides will prefer to cooperate. ("Mutual assured destruction"?) |
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# Some voting systems, such as [[Majority Choice Approval]], try to exploit the fact that each faction is not a single coordinated entity, but a group of individual voters. The idea is that if a small number of voters defect, they should be ignored; hopefully, in that situation, majority cooperation will be a stable strategy. |
# Some voting systems, such as [[Majority Choice Approval]], try to exploit the fact that each faction is not a single coordinated entity, but a group of individual voters. The idea is that if a small number of voters defect, they should be ignored; hopefully, in that situation, majority cooperation will be a stable strategy. |
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# Other voting systems, such as [[ICT]], try to exploit the fact that in a real-world election, A and B are never perfectly balanced; one subfaction is always larger. In this case, a voting system can encourage the smaller group to cooperate by threatening to elect C (punishing both groups) if the smaller group defects. The |
# Other voting systems, such as [[ICT]], try to exploit the fact that in a real-world election, A and B are never perfectly balanced; one subfaction is always larger. In this case, a voting system can encourage the smaller group to cooperate by threatening to elect C (punishing both groups) if the smaller group defects. The chicken dilemma criterion is passed only by this kind of voting system. |
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The chicken dilemma happens when there is a [[Condorcet winner]] and a majority Condorcet loser, but not a majority Condorcet winner. In many voting systems, supporters of one of the two similar candidates have a dilemma, like a game of "chicken": they can either "cooperate" and support both similar candidates, helping to ensure the opposing plurality candidate loses but risking a win by the less-preferred of the similar ones; or they can "betray" and support only their favorite candidate, trying to take advantage of cooperation by the other side. |
The chicken dilemma happens when there is a [[Condorcet winner]] and a majority Condorcet loser, but not a majority Condorcet winner. In many voting systems, supporters of one of the two similar candidates have a dilemma, like a game of "chicken": they can either "cooperate" and support both similar candidates, helping to ensure the opposing plurality candidate loses but risking a win by the less-preferred of the similar ones; or they can "betray" and support only their favorite candidate, trying to take advantage of cooperation by the other side. |
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ICT, [[Symmetrical ICT]], [[MMPO]], MDDTR, [[IRV]], [[Benham's Method|Benham's method]], [[Woodall's method]] |
ICT, [[Symmetrical ICT]], [[MMPO]], MDDTR, [[IRV]], [[Benham's Method|Benham's method]], [[Woodall's method]] |
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Because CD is so simple, such a simple situation, could there be another simple implementation of it? |
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...maybe one that doesn't speak of numbers of voters in the factions? |
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[[Category:Voting system criteria]] |
[[Category:Voting system criteria]] |