Thursday, April 30, 2009

Majority voting is inconsistent & cyclical

Condorcet's voting paradox demonstrates how solid democracy's foundation truly is.

Persons 1,2,3 are voting for candidates A,B,C with the following individual preference lists:
Person1: A>B>C
Person2: B>C>A
Person3: C>A>B

Using a majority voting rule, we can see that A would beat B, since A>B in two out of three peoples' preference lists. Similarly, B>C and C>A. 
But then A>B>C>A which is obviously unreasonable. 
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1 comment:

  1. UnknownJanuary 21, 2010 at 10:38 AM

    Hi there,

    The reasoning is wrong, which is why it is cyclical. A>B only if the contest is between only A and B. Likewise, if the contest is only between B and C, then B>C, if only between C and A then C>A. If all three are combined, then you can't use this to deduce that A>B>C>A, rather then A=B=C it seems.

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