Allan F.'s extended reply to Mike M. on the relationship of value to nature is spot on. While I'm not very ofay with the Red-Green discussion, this exchange seems to illustrate Jim D.'s problem with the word value. In the Marxist sense its about social relations, in the classical and neoclassical sense its about prices, and in the colloquial sense its about being valued in general. Nature has value in the latter sense, it can be shadow priced in the second sense, but it has no relation to value in the Marxian sense. As Allan points out eloquently value is part of an analysis of a system of human relations. In this way the economy is a fundamentally different kind of system from the ecology. Though ecologists speak of economic factors, what they mean is processes of matter-energy transfer. It may be possible to reduce the ecology to a complex system of matter-energy transfer. It is not appropriate to do this with the human economy as it is in some fundamental sense a system of social relations. Thus the human system and the natural system must be analyzed differently and one is unlikely to be able to find any measuring rod common to both. Both systems interact however. The human economic system draws resources from the eco-system and discharges products into it. This relationship is inevitably competitive. Resources (like space) devoted to the human economic system become unavailable to the eco-system and therefor threaten its reproduction. Similarly human discharge into the eco-system has the potential to threaten it as well. Since the human economy, which we value almost by definition, competes with the eco-system which exists outside of human valuing, how do we arbitrate these competing claims. This is the source of the desire for the common measuring rod which could "value" incremental bits of one against incremental bits of the other. As no such valuing mechanism will be found what do we do? One might argue that the destruction of the eco-system will lead to the destruction of the human economy and hence their is no real conflict between the two. While complete destruction of the eco-system is incompatible with human existence, plenty of intermediate levels of destruction clearly are and have in fact already been accomplished. It seems to me that the only solution to this problem is to independently designate the preservation of the eco-system at its current level of diversity as a bedrock value which then places physical limits on the size of the human economy in terms of both its resource use and its discharge into the environment. Terry McDonough