Politicians talk a lot about the Laffer Curve since it concerns tax rates and tax revenue. The Laffer curve is actually quite simple, and is completely logical. Of course we don't know the optimum position on curve. Here is a video that explains the curve.

http://www.youtube.com/watch?v=fIqyCpCPrvU

Democrats are willing to raise taxes so much that revenue is lost to achieve their goal of economic equality; they want to punish the rich. Republicans would like to be on the up side of the curve to encourage economic development.