I asked one of the nation’s top medical ethicists, Arthur Caplan of New York University, if there’s anything unseemly about entering people in a lottery to persuade them to help end the pandemic. “Nah,” he said cheerfully. “There’s nothing wrong with rewarding people for following healthy practices. And once you start thinking about fishing licenses and free beer, it’s not a big jump to paying people outright.” Lotteries appear especially effective, behavioral economists say, because those big dollar figures are eye-catching — and because most of us are bad at evaluating odds, especially long ones. “Lotteries are highly motivating if you’re trying to convince someone to change a behavior,” Katy Milkman of the University of Pennsylvania’s Wharton School told NPR. “People overweight the very low probabilities of winning.”