Recent debates over the economics of climate change underscore the importance of what at first blush is a narrow technical issue in welfare economics and cost-benefit analysis (CBA). Yet even before the need to study the economics of climate change, debate over both nuclear energy policy and water resource policy highlighted the fateful role that social discount rates play in policy prescriptions (Lind 1982, p. 2). In each of these spheres (and in many others as well), the social discount rate influences the degree of concern society displays about a policy’s effects on individuals in the future. This commentary aims to provide a non-technical introduction to some of the key ethical issues and arguments surrounding the choice of social discount rates.