Noah Smith begins this article by praising Greg Mankiw's intelligence and the success of his introductory economics text. He ends the article by reminding us again that Mankiw is very smart, but he chastises him for assuming that the opponents of the Pacific trade agreement are stupid. Sandwiched in between his ode to Mankiw's intelligence, he criticizes Mankiw for over simplifying his defense of the trade agreement. Mankiw made the traditional case for free trade, which is not the same thing as a trade agreement. Trade agreements are more about protecting corporate intellectual property rights, and the mechanism for settling disputes between corporations and nation states, than they are about free trade. The comments that follow this article are quite good on this point. My concern about Smith's critique of Mankiw is that it was too narrow.
Greg Mankiw is prominent economist, and like most highly educated academics, he is not stupid. Smith only reminded us of this because publically attacking a prominent economist can be harmful to the career of a newly minted economist. Accusing Mankiw of over simplifying his defense of the trade agreement, perhaps because he is so smart, will not get him in trouble. Mankiw's use of his intelligence is another matter. He has consistently used his brains, and his prominence in his profession, to serve the most powerful interests in our society. Economics has very little to say about morality or society in general. Mankiw likes it that way. Trade agreements have little to do with economic theory. They have a lot to do with morality and social welfare.