[EM] Arrow's Theorem.

Eric Gorr eric at ericgorr.net
Mon Jul 14 12:09:03 PDT 2003

At 1:17 PM -0500 7/14/03, Adam Haas Tarr wrote:
>So, given only some very reasonable assumptions about the nature of voter
>preferences and election methods, I have demonstrated why no reasonable
>method can be expected to pass IIA.  This is why I think Arrow's theorem,
>while perhaps elegant, is of little value as a practical guide to picking
>an election method.

Of course it is of little value in picking an election method, as his 
theorem shows that a good election method (when one moves beyond two 
choices) does not exist.

However, it is not necessary to throw out IIA to find an election 
method that is good - one only needs to weaken it. IIA is the aspect 
of Arrow's Theorm that many people would agree is the area where a 
weakened condition is reasonable. After all, we do need to be able to 
choose from more then one option and naturally want to find the best 
way of doing so.

Now, if you wish to come up with your own set of criteria for 
selecting a good election method, that is completely different from 
the criteria that Arrow proposed, you are welcome to. There could be 
a Nobel Prize in it for you as there was for Arrow.

Until that point, what Arrow developed is an excellent place to start.

== Eric Gorr ========= http://www.ericgorr.net ========= ICQ:9293199 ===
"Therefore the considerations of the intelligent always include both
benefit and harm." - Sun Tzu
== Insults, like violence, are the last refuge of the incompetent... ===

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