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Empirical results from experimental economics and neuroscience have uncovered regularities in human behavior that may provide a base for new approaches to welfare theory and economic policy. These empirical findings do not challenge basic economic concepts but they do imply that our assumptions about “rational behavior”, “opportunity cost”, and “social welfare” should be revised using sound scientific evidence and methods. This research has the potential to make benefit-cost analysis more reflective of how people value gains and losses, and more responsive to considerations of environmental and social responsibility.

The field of economics is currently undergoing a revolution in the basic assumptions used to model consumer and firm behavior (Kahneman et al., 1997, Gintis, 2000 and Fehr and Fischbacher, 2002). The traditional model of “rational economic man” underlying cost-benefit analysis has been found to be an inadequate description of actual human behavior (Kahneman and Tversky, 1979 and Güth et al., 1982) and a poor predictor of individual choice (Field, 2001, Henrich et al., 2001 and Glimcher et al., 2005). Empirical results from game theory, behavioral, and experimental economics have uncovered regularities in human behavior that may provide a base for new approaches to welfare theory and economic policy (Kahneman and Sugden, 2005 and Layard, 2005). These new approaches have far-reaching implications for environmental valuation and benefit-cost analysis (BCA) (Gowdy, 2004) but contemporary environmental economics largely ignores these recent theoretical and empirical advances (Knetsch, 2005). Recent research results have the potential to make BCA more reflective of actual human decision-making and more responsive to considerations of environmental and social sustainability. The traditional economic worldview underlying BCA, and associated definitions of sustainability, is rooted in mid-twentieth century welfare economics with its key assumptions about rationality, efficiency, and the ability of policy makers to identify Potential Pareto Improvements (Gowdy, 2004 and Bromley, 2006). The standard economic approach to environmental valuation and policy is forcefully spelled out in several high profile guidelines for economic analysis (Arrow et al., 1993, Arrow et al., 1996 and U. S. Environmental Protection Agency, 2000). These papers are commendable in their advocacy of transparency and consistency in designing environmental protection policies, but they are flawed by a rigid adherence to an outdated economic methodology. In these guidelines, contrary to an expanding body of evidence from experimental economics, improving the human condition (increasing social welfare) is equated with increasing per capita income, and “rationality” is defined as conforming to the axioms of consumer choice embodied in Homo economicus. 1 There is a kind of unconscious “bait and switch” argument present in standard economic analysis. Advocates of the standard approach to BCA usually begin with the very reasonable observation that people try to do the best they can with the limited resources at their disposal and that individuals are generally the best judge of what is best for them. However, the facts that people act in their own best interest, that they respond to incentives, and so on, does not justify accepting standard BCA assumptions. Income is an important component of well-being but there are other, equally important, contributors. 2 People respond to a variety of non-monetary (as well as monetary) incentives. Self-interest includes acting fairly towards others, adhering to social norms, and enforcing these norms even at cost to oneself. Preferences include things like inequality aversion, loss aversion, maintaining or improving one's social position relative to others, and non-linear and non-uniform discounting of the future. Recent advances in economic theory and a growing body of empirical findings call into question many of the underlying assumptions of the standard approach (Gintis, 2000, Gowdy, 2004 and Gowdy, 2005). These standard assumptions include (1) equating consumption with well-being, (2) setting aside questions of distribution and relative income by invoking the notion of a Potential Pareto Improvement, (3) implicitly assuming that money is a universal substitute for anything, and (4) assuming that preferences are stable and self-regarding so that the benefits and costs to individuals are independent and additive. Behavioral experiments, neuroscience studies, and game theoretic experiments have demonstrated that market consumption cannot be equated to well-being, lexicographic preferences are prevalent, especially with regard to environmental features, and that preferences are other-regarding. How individuals value monetary payoffs depends on social context, relative position, and the reference point of the valuation. The assumptions underlying the standard BCA approach are at odds with the observed human behavior and they yield poor predictions of the economic decisions people actually make. What do the new economic models of human behavior mean for BCA?

Standard BCA proceeds by making a number of highly unrealistic assumptions about human preferences. It is assumed that people have clearly defined preferences over all relevant outcomes related to their well-being. It is assumed that well-being can be equated with (properly adjusted) measures of income. It is assumed that these preferences are stable, context independent, and internally consistent (Sugden, 2005). Literally hundreds of scientific papers published now routinely in every major economic journal have shown these assumptions to be at odds with actual human behavior. Benefit-cost analysis was considerably improved when non-market sources of well-being began to be in BCA estimates. However, estimating non-pecuniary values uncovered many “anomalies” in preference formation including the WTA–WTP disparity, context dependent valuation, lexicographic preferences and so on. It is now time to take BCA to the next level and incorporate more realistic assumptions about human behavior, human well-being and preference formation. This does not mean throwing out powerful, basic economic concepts developed over the last century. It does mean defining and applying concepts like “rational behavior”, “social welfare”, and “opportunity cost” using empirical evidence and sound scientific methods.