The four basic conditions identified by Dr. Karl-Henrik Robert are not something new. The first definition of sustainable development came from Rambrudunt report. Dr. robert has just produced a value added definition by outlining the and .
Sustainable development is a phenomenon, which, as the UNDP explains, addresses both equity with in generation and equity among generations enabling all generations, present and future, to make the best use of their capabilities. In this world of disturbing contrasts, the ideal of sustainable growth is the only ray of hope capable of bringing the development process within the carrying capacity of nature, giving the highest priority to environmental regeneration- to protect the opportunities of future generations.

The subject matter of Sustainable Development is composed of contributions from ecology, economics, anthropology, sociology and psychology, and computer science. Its repertoire is bolstered by other interdisciplinary work such as system science and nonlinear dynamics; chaos, catastrophe, and complexity theory are showing up regularly in the literature1. The concept of sustainable development dates back to the early 1970s and the Club of Rome report, Limits to Growth, was probably the cornerstone piece of literature that got the whole freight train rolling. (Meadows, D. H., Meadows, D. L., Randers, J., & Behrens, W. W. III (1972). The limits to growth New York: Universe) The United Nations Earth Summit in Rio de Janeiro, 1992, is seen as the major event that organized coordinated efforts of scientists and social service organizations. Perhaps United Nations' Agenda 21 is the most comprehensive list of jobs undone by the world community. (United Nations (1992). Agenda 21: Programme of action for sustainable development. New York: United Nations)

So far Sustainable Development does not have a core theory from which everything else proceeds. Rather, it lives by an open-textured definition, and is defined by the topics researchers have an opportunity to delve into. A core theory may be on its way soon.

Does it have a set of principles to which scientists and social activist organizations agree? Tom Abeles started a discussion on that very subject on Sustainability Net this past year. They seemed to agree on the notion of fair distribution of the earth's resources, but agreements break down while considering what "fair" actually meant.

Are there criteria that tell us when sustainability has been reached? The UN has a project team working on that subject right now. Some definitions are centered around food supply, but food is not the only concern of human society. After the definition, the next challenge is to operationalize those definitions into scientifically sound principles.