Chicken dilemma: Difference between revisions
Point out the relation between the chicken dilemma and the criterion named after it, and fix some grammar.
(A little restructuring; I'll explain more on the talk page) |
(Point out the relation between the chicken dilemma and the criterion named after it, and fix some grammar.) |
||
Line 1:
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.
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.
== Definition ==
Below are two definitions of the Chicken Dilemma criterion; "CD" and "CD2".
=== CD ===
Line 23:
CD is sufficient, as-is, but here is a non-numerical definition:
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.
'''Premise:'''
Line 70 ⟶ 68:
# 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 [[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.
# 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
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.
Line 87 ⟶ 85:
ICT, [[Symmetrical ICT]], [[MMPO]], MDDTR, [[IRV]], [[Benham's Method|Benham's method]], [[Woodall's method]]
[[Category:Voting system criteria]]
| |||