About 70 Harvard students showed their disapproval of an introductory economics course by walking out of class last week, the Huffington Post reports. In an open letter to their professor, Greg Mankiw, the students explained that their actions were driven in part by a desire to show solidarity with the Occupy Wall Street movement. On his blog, Mankiw notes [1] that the students’ actions are ironic because the class topic for the day was income distribution and the growing gap between the top one percent and the bottom 99 percent. Mankiw was the chairman of the Council of Economic Advisers under President George W. Bush. He is now an advisor on the Mitt Romney campaign…