Mankiw is Karl Rove's puppet. This proves it:
It's strange what's happened since then. When he became a New York Times columnist, he decided to abandon writing about economics as an economist does. He's very liberal, which is fine—most of my friends at Harvard are liberal—but whenever someone disagrees with him, his first inclination is to think that person is either a liar or a fool. It's amazing to me that an academic would behave that way. The one thing that I value about academia is open-mindedness, the premise that all ideas and different points of view should be considered. No one has a monopoly on the truth. The one defining characteristic of a good professor is to be open to all viewpoints.
Link via Marginal Revolution.