Knowledge, ignorance and the evolution of complex systems

The paper explores the basis for decision‐making and policy with regard to the Environment. Clearly these should be based on knowledge of possible consequences and accompanying risk assessments involving the linked behaviour of the many interacting human actors within a socio‐economic system and the ecological, and physical systems in which they are embedded. The paper describes the Complex Systems approach to these problems, showing the kind of models that are required in order to obtain whatever limited knowledge is possible about the co‐evolution of the human and environmental systems involved. Several practical examples are described and the models briefly presented. These are shown as examples of what should be required for the creation of the necessary basis for making policy and decision explorations with an integrated view of the system as a whole, instead of separate parts studied in detail by experts of specific disciplines. This provides a framework for making real use of the “knowledge” of disciplinary experts, and linking their narrow views to the overall, practical consequences in the real world of possible policy options.