ABSTRACT
Discounting is the process by which the authors translate the value of expected future costs and benefits into present-day values. It is a fact of life that, taken as a whole, society discounts future values. Economists note that as borrowers people are willing to pay an exponential interest penalty to acquire resources now; conversely, savers expect to be rewarded for their forbearance with an exponential interest premium on bank deposits and investments. Ethologists, however, take a hyperbolic approach to discounting. The difference is of considerable importance over long timeframes, with important implications for sustainability. The results of standard economic discounting practice for long-term analysis have been recognized by many as being unsatisfactory for some time. Recent concern for long-run values like biodiversity accentuates the discounting problem. The need to better inform public policy, and the increasing importance to society of resource and environmental sustainability in decision-making, make interdisciplinary work on discounting of pressing importance.
