ence, reflecting strategic objectives. Value functions assume that, given two alternatives, the individual decision maker can say one of two things about them: one alternative is better than the other, or both alternatives are equally good.

The assumptions underlying the concept of value functions are particularly weak when considering the problem of establishing group preferences for environmental attributes. There are two reasons for this. First, to choose between two or more alternatives, the implications of the choice must be fully understood. Otherwise, the choice is meaningless and essentially random. When experts cannot establish the incremental effects of the potential changes in environmental release and resource consumption of two or more alternatives, it is virtually impossible to expect these experts, much less the public at large, to say that one is preferable to the other. Second, even if all the implications of each choice were characterized to the complete satisfaction of all members of the group, individuals still do not have a consistent set of objectives when confronted with environmental choices. For example, some might believe that preventing global warming is more important than reducing urban air pollution, whereas others might think that neither of these objectives is as important as maintaining and improving human health. This lack of a consistent set of priorities in the environmental area essentially eliminates the possibility of constructing a useful value function.

Although the EPS system is a commendable attempt at simplifying the enormous detail of inventory data, the system's developers have pointed out that it is based on their subjective value judgments, which are not necessarily supportable in all situations worldwide. The goals set out by the Society of Environmental Toxicology and Chemistry and the EPA for improvement analysis based on life-cycle inventories are laudable, but they can only be realized by some type of consensus on the value of avoiding environmental degradation.

This suggests that achieving the final stage of LCA will require the development of a basis for devising (and revising) this consensus. In the absence of a common strategic objective, it will be impossible to use LCA to designate ways to achieve environmental improvement beyond straightforward strategies for pollution prevention or the use of precautionary principles. A strategic consensus is required to trade off competing environmental, economic, and engineering goals.

Summary

LCA is a technique that has already shown great promise for improving our understanding of the wider implications and relationships that must be taken into consideration when incorporating environmental concerns into technical decision making. As these concepts diffuse into industrial and technical decision making, LCA will enable industry and government to find ways to both increase efficiency and reduce harm to the environment.

However, practitioners and proponents must guard against using LCA to de-



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