a cynical opinion on Warren Buffet's tax talking point

The 2nd richest moneybags in the U.S., Warren Buffet, always championed the talking point of levying higher tax on the rich to justify the social fairness. An interesting contrarian opinion raised by a Harvard University professor on Buffet's seemingly admirable altruistic talking point. http://gregmankiw.blogspot.com/2012/11/a-master-of-tax-avoidance.html