ABSTRACT
S ustainability has become a mantra for the 21st century. It embodies the promise of societal evolution towards a more equi-
table and wealthy world in which the natural environment and our cultural achievements are preserved for generations to come. This promise touches upon elementary hopes and fears, which have both guided and challenged scores of scholars in the past. The quest for economic growth and social equity has been a major concern for most of the past 150 years. By adding concern for the carrying capacity of natural systems sustainability thus ties together the current main challenges facing humanity. While there has been extensive work on all three problems over the past four decades, it was only the 1992 Earth Summit in Rio that brought the widespread acceptance of politicians, NGOs and business leaders that none of the three problems can be solved without also solving the other two (Keating, 1993).
