Economic capital should be maintained. The widely accepted definition of economic sustainability is maintenance
of capital, or keeping capital intact. Thus Hicks’s definition of income–the amount one can consume during a
period and still be as well off at the end of the period–can define economic sustainability, as it devolves on
consuming value-added (interest), rather than capital
ž Economic and manufactured capital is substitutable. There is much overcapitalization of manufactured capital,
such as too many fishing boats and sawmills chasing declining fish stocks and forests
ž Historically, economics has rarely been concerned with natural capital (NC) (e.g., intact forests, healthy air). To the
traditional economic criteria of allocation and efficiency must now be added a third, that of scale (Daly, 1992). The
scale criterion would constrain throughput growth–the flow of material and energy (NC) from environmental
sources to sinks
ž Economics values things in money terms, and has major problems valuing NC, intangible, intergenerational, and
especially common access resources, such as air. Because people and irreversibles are at stake, economic policy
needs to use anticipation and the precautionary principle routinely, and should err on the side of caution in the
face of uncertainty and risk