Sidgwick criticised the convention to discount the utility of future generations vis-a-vis that of the present generation, as it discriminates future generations simply for the order of their appearance vis-a-vis the present generation along the time-axis. Pigou coined the principle of intergenerational equity that there should be no discrimination in Sidgwick's sense. Unfortunately, Diamond showed that there exists no continuous and Paretian preference ordering satisfying the Sidwick- Pigou intergenerational equity principle over the set of infinite utility streams. This paper surveys the current state of the axiomatic approaches to intergenerational equity so as to orient the future study in this arena.
