From Wikipedia, on arguments for progressive taxation
"The higher one's income, the greater the fraction of it that tends to consist of economic rent rather than rewards for any commensurate contribution to production. By definition, economic rent is a factor payment exceeding that required to place a factor in its most productive use, so it can be taxed away entirely without impairing wealth production. Consequently, in the absence of taxes specifically levied on economic rent, a steeply progressive tax on the highest incomes can be expected to fall almost exclusively on economic rent, minimizing the excess burden of such taxation."
Thoughts?