Developing principles of goad practice in integrated environmental assessment

In integrated environmental assessment, unlike many other fields of quantit ative social and environmental science, there is a keen awareness of the ne ed for quality and assurance, and principles of good practice. This paper e xplores what is involved in developing and maintaining good practice. The p roblems of quality assurance in such a field, apparently scientific but in practice something else, must be confronted. The existing approaches to eff ective practice are scrutinized: the pitfalls of the quantitative path, the perils of GIGO with computers, and the hazards of modelling. The struggles of modellers with uncertainty are chronicled, first by recalling the IIASA energy study, and then reviewing J. van der Sluijs's research. The spectre haunting all these mathematical socio-environmental sciences is 'immaturit y', this is explored, and analogies are drawn with the design disciplines a nd history. Finally, the insights of 'Post-Normal Science' are applied, wit h the distinction between research and professional practice, the qualitati ve analysis of quantitative information, and the usefulness of the pedigree category in characterizing information quality. The Post-Normal approach i s discussed as a possible way forward from the insoluble problems of achiev ing good practice, and maintaining quality, in the field when it is conceiv ed in purely quantitative terms.