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Chicken dilemma: Difference between revisions
Copy/paste merge of Chicken dilemma criterion oldid=6800, using that article as the summary for now. Still editing/merging...
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(Copy/paste merge of Chicken dilemma criterion oldid=6800, using that article as the summary for now. Still editing/merging...) |
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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. That is to say, 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.
Here's an example of a chicken dilemma scenario, in the format of "#voters:true preferences":
* 33: A>B>>C
* 22: B>A>>C
* 45: C>>A=B
== Details ==
One type of election scenario which is particularly fraught is 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). That is, if we assume each faction has a single, coordinated strategy defined as "cooperate" (vote both candidates A and B above bottom) or "defect" (bullet vote, with only the favorite above bottom); and that each faction values its preferred choice at 10, its less-preferred choice at 8, and candidate C at 0, many voting systems lead to the following payoff matrix:
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