10.2190/9923-JM1G-XKCQ-H7A4 9923JM1GXKCQH7A4 1 Bounded Rationality and the Rational Bounding of Environmental Models 1 14 20020509 20020509 20020509 20020509 9923JM1GXKCQH7A4.pdf http://baywood.metapress.com/link.asp?target=contribution&id=9923JM1GXKCQH7A4 1 Douglas J. Crawford-Brown Department of Environmental Sciences and Engineering, University of North Carolina, Chapel Hill Models of environmental systems find use in three primary applications. They might form the basis of scientific research, where they serve both to explain environmental functioning and to act as a means of prediction. They also form the basis of regulatory decisions, in which they are called upon to make predictions of risk under varying conditions. Finally, environmental models may be used to suggest engineering changes to the environment, changes designed to bring about a different state of the environment. Due to incomplete knowledge of environmental systems, however, the models used in these roles usually are bounded, meaning that they ignore (or cannot account for) specific aspects of an environmental system which play a part in the overall behavior of specific systems to which the models are applied. Despite this bounding, these models still may form a rational basis for action or decisions. This rationality may only be obtained, however, when the intention underlying use of a model is limited to the situations in which the bounded model is applicable. This article presents a general discussion of how rational decisions may be made in light of bounded models of the environment. It is suggested that the bounding of the model must correspond to the bounding of the rationality underlying the decision. An example is provided, using a model of the risk from radon in homes, which illustrates how the bounding of rationality may be reflected in the bounding of an environmental model. N. Maxwell, <i>From Knowledge to Wisdom</i>, Basil Blackwell, Ltd., Oxford, England, 1984. D. J. Crawford-Brown and C. Cothern, A Bayesian Analysis or Scientific Judgment of the Uncertainties in Estimating Risk Due to Rn-222 in U. S. Public Drinking; Water Supplies, <i>Health Physics, 53</i>, pp. 11-21, 1987. C. R. Cothern and W. L. Marcus, Estimating Risk for Carcinogenic Environmental Contaminants and Its Impact on Regulatory Decision Making, <i>Regulatory Toxicology and Pharmacology, 4</i>, pp. 265-274, 1984. D. J. Crawford-Brown, Age Dependent Lung Doses from Ingested Rn-222 in Drinking Water, <i>Health Physics, 52</i>, pp. 149-156, 1987. U. S. Environmental Protection Agency, <i>Draft Criteria Document for Rn-222 in Drinking Water</i>, Office of Drinking Water, Washington, D. C., 1985. D. J. Crawford-Brown, Dosimetry, in <i>Environmental Radon</i>, R. Cothern and J. Smith (eds.), Plenum Press, New York, NY, pp. 173-212, 1987. D. J. Crawford-Brown, An Analysis of the Reduction and Increase in Risk Produced by Various Mitigation Procedures for Radon in Home Air, paper presented at the Annual Meeting of the Fine Particle Society, Boston, MA, August 1987 (a copy of the study results may be obtained by writing to the author of this article).