Abstract: Some areas of philosophical value theory could benefit from an infusion of methods from economics. I shall talk about two examples. One is the theory of the value of equality, which is often understood as a debate between egalitarianism and prioritarianism. The other is population ethics. These are quantitative topics involving numbers of people. So they call for some of the quantitative, mathematical analysis that economists are good at. Indeed economists have written extensively on these very topics, and have made discoveries that philosophers ignore at their peril.