Strong versus weak sustainability: Economics, natural sciences, and "consilience"

The meaning of sustainability is the subject of intense debate among environmental tal and resource economists. Perhaps no other issue separates more clearly the traditional economic view from the views of most natural scientists. The debate currently focuses on the substitutability between the economy and the environ ment or between "natural capital" and "manufactured capital"-a debate captured in terms of M elk versus strong sustainability. In this article, we examine the various interpretations of these concepts. We conclude that natural science and economic perspectives on sustainability are inconsistent. The market-based Hartwick-Solow "weak sustainability' approach is Far removed from both the ecosystem-based "Holling sustainabilily' and the "strong sustainability" approach of Daly and others. Each of these sustainability criteria implies a specific valuation approach, and thus an ethical position, to support monetary indicators of sustainability such as a green or sustainable Gross Domestic Product (GDP). The conflict between "weak sustainability" and "strong sustainability" is more evident in the context of centralized than decentralized decision making. In particular, Firms selling "services" instead of material goods and regarding the latter as "capital" leads to decisions more or less consistent with either type or sustainability. Finally, we discuss the implications of global sustainability for such open systems as regions and countries. Open systems have not been dealt with systematically for any of the sustainability criteria.