Gutes, Maite Cabeza. 1996. "Commentary: The Concept of Weak Sustainability." Ecological Economics 17(1996): 147-156.

Thesis:

'Weak sustainability' is a direct application of growth theory with exhaustible resources (p.156). It does little to direct concern toward distributional and intergenerational equity, or to respond to the tensions between growth needs and environmental protection, which are the concerns that are central to the sustainable development concept.

Summary:

Gutes introduces 'strong' and 'weak sustainability' as attempts within the discipline of economics to develop sustainability indicators for assessing economies. Proponents of 'strong sustainability' regard natural capital as providing some functions that are not substitutable by man-made capital. Sustainability is viewed in terms of non-decreasing stock of natural capital to be enjoyed by future generations.

From the 'weak sustainability' perspective, "an economy is considered to be sustainable if its savings rate is greater than the combined depreciation on natural and man-made capital' (p.147). Since natural and human-made capital are seen as substitutable, sustainability is viewed in terms of non-decreasing total capital.

Gutes contends that weak sustainability is a "direct application of the savings-investment rule from growth theory with exhaustible resources" (p.148). The goal of growth theory was to determine under what conditions an economy would be able to have a stream of constant level of consumption per capita, indefinitely. The savings investment rule (Hartwick-Solow) argues that in order to meet this condition, "society should invest all of the current returns obtained from the utilization of the stock of exhaustible resources" (p.149). This relies heavily upon the assumption of the substitutability of natural and man-made capital.

Gutes links growth theory and weak sustainability in the instance where: (1) the definition of sustainability is restricted to non-declining consumption per capita; and (2) the environment-economy relationship is described by introducing "an aggregate input called "natural capital" into the production function, with no special treatment for such input except for its existence in limited quantity" (p.150). This second assertion Gutes sees as a limitation on the concept of 'weak sustainability' because crucial links between the environment and the economy are excluded from the concept, such as the need for natural capital in order to produce human-made capital, the role of natural capital in providing life support, and the absorption of waste by air, land and water (p.150).

Gutes charges that while growth theory was merely intended to examine the conditions under which a constant stream of consumption per capita could be maintained, "the concept of sustainability arose from a much broader concern about the conflicts between economic activity and the environment, with special emphasis on inter- and intra-generational equity" (p.150). The concept of 'weak sustainability', in Gutes' view, does not effectively address any of those concerns.

Gutes criticizes proponents of 'weak sustainability' for not forthrightly stating their assumptions, such as high levels of substitutability between natural and human-made capital; the aggregation of capital in categories without formal testing; valuation of natural capital through market prices, which depend upon the unequal distribution of income; and the lack of recognition of the necessity of natural capital in the production of man-made capital (p.155). In addition, Gutes charges that the 'weak sustainability' index inappropriately simplifies the calculation of environmental degradation into a single numerical value. The author concludes that the concept of 'weak sustainability' rests upon a weak foundation, both theoretically and empirically, and fails to promote concern by the public about central sustainability issues (pp.155-56).

Keywords: production functions, weak sustainability, growth theory, exhaustible resources, natural capital, substitutability