Last February, W’s top economic advisor Gregory Mankiw took a drubbing for being a straight shooter. He defended outsourcing as the latest manifestation of trade, and something that would be good for society. Sadly, politicos on both sides of the aisle reacted as if he defended wife beating. Now Mankiw’s at it again, this time telling the truth about Social Security: “The [Social Security] benefits now scheduled for future generations under current law are not sustainable given the projected path of payroll tax revenue,” Mankiw said at a recent tax policy conference. “They are empty promises.” And, as Jacob Sullum explains, Mankiw is once again getting drubbed. No wonder he’s leaving his post.