From my article in American Thinker, Everything that Counts:

Vast inequalities may harbor the potential for social unrest, but that is muted by social mobility.  Oprah and Andre Young (Dr. Dre) may have been born in poverty, but that has not kept them from rising to the top one tenth of one percent.  Here is a defining question: did the dramatic rise in the fortunes of Dr. Dre and Oprah increase or decrease inequality as a whole?

Here is the central problem with Piketty’s task: the data on inequality measures categories, not individuals.

Individuals rise and fall among categories, often taking leaps as luck and talent unfold.  Oprah’s success increases inequality, but her success also demonstrates an increase in mobility.  Individuals may buy a lottery ticket knowing that the odds are against them if they know that their opportunity is equal to other lottery ticket buyers.  They will be less likely to buy a ticket if they think the game is rigged (i.e., crony capitalism).  For many, the mobility and the equality of opportunity are most important.  We hold no grudge against the winner, because we understand that the winner could be we.

While Piketty reviews a history of inequality, we should realize that the inequality of the feudal society of the middle ages, where force kept the poor in a lifetime of poverty, is vastly different from the inequality from a system where innovations spur spectacular success, while benefiting large proportions of other people.  Does anybody with an iPhone hold a grudge against Steve Jobs and his billions of dollars of wealth, or the wealth of Sergi Brin of Google?

All inequality is not equal.