Social thinkers frequently remind us that people differ in their views on what constitutes personal well-being, but that even when they don't differ, they disagree over the extent to which one person's well-being can be permitted to be traded off against another's. In this paper I show, by offering an account of the development of development economics, that in professional debates on social policy, economists speak or write as though they agree on values but differ on their reading of facts. A number of ethicists have concluded from this near-exclusive interest in facts that modern economics must be an ethical desert. It is shown here that the reason research economists analyze facts rather than values is that modern economics is built on broad ethical foundations, capable of being reduced as special cases to the various ethical theories that are currently on offer. Ethics has taken a back seat in modern economics not because contemporary economists are wedded to a “value-free” enterprise, but because the ethical foundations of the subject were constructed over five decades ago and are now regarded to be a settled matter.