Generation-adjusted discounting in long-term decision-making

This paper analyses the choice of an intergenerational discount rate as well as a method for intergenerational discounting. It is shown that the pure time preference rate is irrelevant for intergenerational comparisons. However, the application of the growth time preference rate - with respect to consumption - is a necessary condition for intertemporal utility-maximization. Opportunity costs should be taken into account not by discounting with their internal rate of return, but by calculating consumption equivalents (shadow prices of capital). Thus, an intergenerational discount rate has to be based on the time preference approach. These considerations lead us to the formulation of a new discounting technique, 'Generation Adjusted Discounting' (GAD). It takes into account intra- as well as intergenerational aspects. Compared with conventional discounting techniques, we find that the present values obtained by using the GAD noticeably exceed those derived conventionally.