ABSTRACT
Uncertainty may arise as a result of imprecise language in describing the quantity of interest and disagreement about interpretation of available evidence. This chapter discusses various aspects of uncertainty, from initial characterization to methods for quantification where appropriate. Post-normal science called for a search for new approaches to dealing with uncertainty, one that recognized the diversity of stakeholders and evaluators needed to deal with these challenges. Controversy arose about the potential human health effects of a waste incinerator located near Antwerp when an unusually high number of children were found to have congenital defects. Uncertainty will arise when attempting to obtain information about empirical quantities which have some true value that could, in principle at least, be measured. The identification of variables that may have a substantial effect on model output is an important step in any analysis of uncertainty, as it is these variables which are liable to contribute most to the final uncertainty.
