In class we discussed the Condorcet system method of voting. The way this system works is by having voters choose a candidate who would beat every other candidate in a head-to-head, two way race. A Condorcet winner is the candidate most voters choose over all the other individuals. Not all elections will work out to have a condorcet winner. A voting system that always elects a Condorcet
winner when there is one, can be described by the electoral scientists as a system that satisfies the Condorcet criterion. On a side note plurality fails the Condorcet winner criterion. This method of voting can be very complicated at times.
The Independence of Irrelevant Alternatives can be interpreted as if one candidate (X) wins
the election, and a new candidate (Y) is added to the ballot, only X or Y will win the election.
Another example; it is impossible for B to go from a nonwinner to a winner unless at least one voter reverses the order in which B and the winner (A) are ranked. The IIA is a easy method to manipulate so its not very accurate or fair way of voting. Also the Borda count method FAILS the IIA.
If all voters prefer one candidate (A) to another (B), then B should NOT win. This is called a Pareto condition.
In 1951, Kenneth Arrow proved Arrow's Impossibility Theorem: when there are more than two candidates it is impossible to have a voting system that satisfies all these criteria (Pareto, IIA, Condorcet) and always produces a winner. (Except dictatorship!)
I really enjoyed learning about the condorcet voting method. It gives a a different way of thinking of if we would have to vote like this someday on how it would work. I would have to agree with it. I also enjoyed the IIA even though its pretty unaccurate. It made sense to me though. Arrow's impossibility theorem is very accurate to with all the methods.
ReplyDeleteThe Condorcet Method is a good way of voting, but I feel like it would take voters longer to vote. This might even sway voters to not vote because of laziness or not enough motivation.
ReplyDeleteI never heard of this voting method before till we learned it in class last week. It is very interesting but I would have to agree with Ben Steines. I feel it is too complicated. I even get confused sometimes when trying to figure out problems in class with the method. It is a good method but too complicated and difficult to understand for the common people.
ReplyDeleteAs Arrow’s Impossibility theorem shows, none of the voting methods mentioned in class are perfect. His theorem, however, does not have any suggestions as to which of these imperfect methods should be used. A dictatorship is not really voting because only one person makes all decisions. Dictatorships also create plenty of social problems so having a dictatorship would not help.
ReplyDeleteThe Condorcet method is a little confusing to me. Let me see if I got it, is it the best out of 3?
ReplyDeleteGood summary, Marybeth. Just to clarify, though, IIA is not a voting method - it is a criterion that we would like voting methods to meet. That is, we would hope that any method we use does not allow a nonwinner to become a winner even though no one changes their mind about the winner. However, as Arrow's Theorem shows, not all methods do that.
ReplyDeleteAlso, to respond to Ben and Hannah - all the methods (except plurality) require the same thing of voters - that they rank the candidates. The method used to COUNT the votes (Condorcet, instant runoff, Borda, whatever) is what varies. Although Condorcet may be complicated to count, the voters would not be the ones doing that. All they would need to do is rank the candidates, just like in the other methods. Does that make sense?