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Arrow's impossibility theorem: Difference between revisions
Fix redlink to w:Kenneth Arrow; updated links at bottom of page (and removed link to electionmethods.org)
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'''Arrow’s impossibility theorem''', or '''Arrow’s paradox''' demonstrates the impossibility of designing a set of rules for social decision making that would obey every ‘reasonable’ criterion required by society.
The theorem is named after economist [[w:Kenneth Arrow|Kenneth Arrow]], who proved the theorem in his Ph.D. thesis and popularized it in his 1951 book ''Social Choice and Individual Values.'' Arrow was a co-recipient of the 1972 Bank of Sweden Prize in Economic Sciences in Memory of Alfred Nobel (popularly known as the “Nobel Prize in Economics”).
The theorem’s content, somewhat simplified, is as follows.
A society needs to agree on a
* '''unrestricted domain''' or the '''[[universality criterion]]''': the social choice function should create a deterministic, complete societal preference order from every possible set of individual preference orders. (The vote must have a result that ranks all possible choices relative to one another, the voting mechanism must be able to process all possible sets of voter preferences, and it should always give the same result for the same votes, without random selection.)
* '''non-imposition''' or '''citizen sovereignty''': every possible societal preference order should be achievable by some set of individual preference orders. (Every result must be achievable somehow.)
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== External links ==
* [
* [
[[Category:Voting theory]]
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