This paper presents and discusses a model for environmental decision making. The model defines ends, means, subjects, objects and contexts in relation to particular decisions, and hence in relation to particular problems. This entails definition that is flexible with regard to content—for example, whether a particular entity is subject or object. To improve understanding of the limits of applied knowledge, likely types and levels of ignorance regarding ends, means, subjects, objects, and contexts are discussed. This provides guidance to the selection (...) of appropriate means for defining and addressing environmental problems. (shrink)