Rob Stavins explains the rationale for discounting the future in benefit-cost analysis in his Nov/Dec 2005 "An Economic Perspective" piece for The Environmental Forum. Here is the intro to Does Econ Analysis Shortchange the Future:
Decisions made today usually have impacts both now and in the future. In the environmental realm, many of the future impacts are benefits, and such future benefits — as well as costs — are typically discounted by economists in their analyses. Why do economists do this, and does it give insufficient weight to future benefits and thus to the wellbeing of future generations?
