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| | Name : | Danny Kleinman | Organization : | N/A | Post Date : | 9/30/2005 |
| Comment : | Here, I suggest, are some desirable criteria for such a voting system.
(6a) Continued
Now imagine that the portions of the spectrum to the left of Gore and the right of McCain are devoid of candidates, leaving a three-candidate race. (a) For McCain to defeat Gore, more voters must lie to the right of Gore than to the left of McCain. (b) For Bradley to defeat McCain, more voters must lie to the left of McCain than to the right of Bradley. (c) For Gore to defeat Bradley, more voters must lie to the left of Bradley than to the right of Gore. But since Bradley is to the left of McCain, the number of voters to the left of Bradley is smaller than the number of voters to the left of McCain. From (a), however, we know that the number of voters to the left of McCain is smaller than the number of voters to the right of Gore, and there the number of voters to the left of Bradley is also smaller than the number of voters to the right of Gore. Therefore (c) cannot occur if (a) and (b) do.l
The above paragraphs---those that follow the map of the political spectrum---constitute an informal proof of a mathematical theorem which says, “When a political spectrum exists, and voters vote consistently with their positions on the political spectrum, there is always a Condorcet candidate.”
Long before Kenneth Arrow won his Nobel Prize in Economics, he proved Arrow’s Theorem, which says that given certain reasonable requirements, no perfect voting system could be devised. However, we needn’t find defects in Arrow’s proof, nor argue that his theorem is false, to seek an optimal voting system. And there is an optimal voting system, a system that satisfies Criteria (1) through (5), satisfies Criterion (6) when there is a Condorcet candidate, and elects a candidate who may reasonably be considered “the most popular” in the rare circumstance that there is no Condorcet candidate. | |
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