Philosophers are accustomed to discussions about how to value lives distant from our own in time and place; economists are not. But in a new book, “Stubborn Attachments: A Vision for a Society of Free, Prosperous, and Responsible Individuals”, Tyler Cowen of George Mason University argues that the moral status of human lives ought not to be traded off over time in the same way that a bond portfolio might be. He puts the results of discounting in evocative terms: given a 5% rate of discount, one human life today is worth 132 a century hence. Is it really ethically acceptable to save one life now at the expense of so many in the future? The lives of humans born decades from now might be difficult for us to imagine, or to treat as of equal worth to our own. But our own lives were once similarly distant from those taking their turn on Earth; the future, when it comes, will feel as real to those living in it as the present does to us. Economists should treat threats to future lives as just as morally reprehensible as present threats to our own.