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| CATEGORIES ABOUT CONDORCET CRITERION | |
| voting system criteria | |
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The Condorcet criterion for a Voting System is that it chooses the Condorcet winner when one exists. Any method conforming to the Condorcet criterion is known as a Condorcet Method . It is named after the 18th century mathematician and philosopher Marie Jean Antoine Nicolas Caritat, the Marquis De Condorcet . COMPLYING METHODS Black, Smith/IRV , Copeland , Minimax , Nanson's Method , Smith/minimax , Ranked Pairs and variations ( Maximize Affirmed Majorities , Maximum Majority Voting ), and Schulze comply with the Condorcet criterion. Approval Voting , Range Voting , Borda Count , Plurality Voting , and Instant-runoff Voting do not. COMMENTARY Non-ranking methods such as Plurality and Approval cannot comply with the Condorcet criterion because they do not allow each voter to fully specify their preferences. Instant-runoff Voting is an example of a method which allows each voter to rank all the candidates, but does not comply with the Condorcet criterion. Consider, for example, the following vote count of preferences with three candidates {A,B,C}:
In this case, B is preferred to A by 501 votes to 499, and B is preferred to C by 502 to 498, hence B is preferred to both A and C. B must then win according to the Condorcet criterion. Using the rules of IRV, B is ranked first by the fewest voters and is eliminated, and then C wins with the transferred votes from B. SEE ALSO |
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