If it is human to make errors, economists are no different from the rest of us in that they make blunders. Theories that enchant us in textbooks often lead us wrong in the actual world, and vice versa. It turns out that even the most famous minds have clumsy feet. Economic concepts, on the other hand, may have remarkable staying power. As the British economist John Maynard Keynes famously observed, “practical men” who value their independence of thought are often “the slaves of some dead economist,” according to his observations. Despite the fact that they have passed their sell-by date, deceptive statements continue to sit on the shelf in the marketplace of ideas.