ABSTRACT
Uncertainty is an inescapable ingredient of life. Even in familiar situations – such as crossing a street – some level of uncertainty inevitably exists. Past experience is relevant for all decisions involving the future, but contexts change and new elements affecting risk may unexpectedly appear. Usually, this residual uncertainty remains within reasonable bounds and human beings make their way in an uncertain and changing world where existing knowledge and experience suffice as guides to future expectations (Pollack, 2003). But where highly complex systems with extensive connectivity and interaction exist, or where novel problems or technology limit experience as a resource, decisions often must be made under conditions of high uncertainty. It is not surprising, as the various chapters in the volume make clear, that in a world of complex systems involving rapid technological change, highly coupled human and natural systems, and a kaleidoscope of social, economic and political institutions, high levels of uncertainty challenge existing assessment methods and established decision and management procedures.
