Like the term error, uncertainty is imbued with many meanings (Kirschenmann 2001). The term may refer to a variety of different things; for instance, people refer to nature, propositions, models, practices, or the future as ‘uncertain’. In many of these cases, the term is used in a loose manner. In some formal denitions of the term uncertainty as ‘absence of certainty’ or ‘lack of knowledge’, uncertainty is taken to refer to our state of knowledge (that is, propositions or models about nature, practices, and their future).* A typical example of a denition of uncertainty is the following:

According to this denition, uncertainty is more or less the same as inaccuracy. Funtowicz and Ravetz (1990) provide a broader characterisation of uncertainty. They distinguish between two main dimensions of uncertainty. Their rst main dimension is the source dimension, which I call the ‘location’ dimension in this discussion. Their second main dimension is the sort dimension:

Along the sort dimension, Funtowicz and Ravetz list three types of uncertainty: ‘inexactness’ (imprecision, usually expressed by a spread); ‘unreliability’ (inaccuracy, usually expressed by a statistical condence

level); and ‘border with ignorance’ (not expressed statistically). Furthermore, they elaborate the concept of ‘pedigree’. The pedigree of a particular piece of information conveys an evaluative account of the production process of that information.