On 5/17/05, MIKE OSSIPOFF <[EMAIL PROTECTED]> wrote: > If Arrow's elusive definition says something different, then of course > there's always the possibllity that Approval and Plurality might fail > Arrow's unposted IIAC.
The full text of Arrow's "Social Choice and Individual Values" (the book version of his PhD thesis) is available for search on Amazon.com. From page 26: "The Independence of Irrelevant Alternatives If we consider C(S), the choice function derived from social ordering R, to be the choice which society would actually make if confronted with a set of alternatives S, then, just as for a single individual, the choice made from any fixed environment S should be independent of the very existence of alternatives outside of S. For example, suppose that an election system has been devised whereby each individual lists all the candidates in order of his preference and then, by a preassigned procedure, the winning candidate is derived from these lists. (All actual election procedures are of this type, although in most the entire list is not required for the choice.) Suppose that an election is held, with a certain number of candidates in the field, each individual filing his list of preferences, and then one of the candidates dies. Surely the social choice should be made by taking each of the individual's preference lists, blotting out completely the deadd candidate's name, and considering only the orderings of the remaining names in going through the procedure of determining the winner. That is, the choice to be made among the ser S of surviving candidates should be independent of the preferences of individuals for candidates not in S." -Bill Clark ---- Election-methods mailing list - see http://electorama.com/em for list info
