Objective and Subjective Judgements in Environmental Impact Analysis

Analyses of environmental impacts, and descriptions of methodologies for conducting them, have not always been explicitly cognizant of the subjective value-judgements that must be made in the process of collecting, refining, assessing, and presenting, objective scientific information. This paper has outlined the types of objective and subjective judgements that are made in each of the following major steps of the analysis: identifying major activities; selecting environmental components; selecting types of impacts; assessing the possibilities and/or probabilities of occurrences; determining the degree of the impacts; determining the time-frame of impacts; designating impacts as positive, neutral, or negative; and determining trade-offs among activities and impacts.

The subjective judgements that must be made are based on values, feelings, beliefs, and prejudices, and are functions of the personal, institutional, professional, and societal, contexts of the analyst. If great care is not taken in making these judgements, and in making very explicit the value-framework used, the effectiveness and credibility of the analyst may be sharply reduced. There is also the danger that society and its decision-makers will be presented with an analysis having so many built-in biases that the legitimate role of the decision-makers in assessing the analysis and then making important value trade-offs is seriously compromised. This paper has attempted to make the nature of the process of analysis explicit with respect to the introduction and treatment of values, so that these problems can be understood and, it is hoped, properly managed by both scientists and decision-makers.