Abstract

The social discount rate typically consists of two components: differences in the marginal utility of consumption across time, and the pure time preference rate as applied to cardinal utility. Within this framework, intragenerational and intergenerational time preference rates must be the same, if we are to avoid strongly counterintuitive results. Both rates, however, can be plausibly equal at zero rather than at a positive level; pure time preference should not necessarily be applied to cardinal utility, even when we apply it to goods. The other component of the discount rate, the marginal utility of consumption, is appropriate only for very small changes in individual wealth; this assumption does not match most of the intergenerational scenarios in question. I conclude that economics does not provide a prima facie case for a positive rate of intergenerational discount for most policy issues.