Gregory Mankiw has a rather silly article in today's NYTimes. The article itself is not worth reading, but presumably it reflects of the quality of economic advice to and from Mitt Romney. He shows that it is not easy to see the difference between earned income and capital gains. But he is not capable of stating the unavoidable conclusion: that earned and non-earned income should be taxed at the same rate.
I have walked out of lectures for lesser errors.