What’s at work here is scarcity--perceiving that you don’t having enough of something--and the way it affects our thinking. As Harvard economist Sendhil Mullainathan and Princeton psychologist Eldar Shafir detail in Scarcity: Why Having Too Little Means So Much--that famished feeling produces a "cognitive tunnel" limiting what we’re able to see. Like a hungry person jumping at the mention of cake, scarcity does crazy things to us. As Sunstein says: