Towards a coherent philosophy for modelling the environment

The predominant philosophy underlying most environmental modelling is a form of pragmatic realism. The limitations of this approach in practical applications are discussed, in particular, in relation to questions of scale, nonlinearity, and uniqueness of place. A new approach arising out of the concept of equifinality of models (structures and parameter sets) in application is outlined in the form of an uncertain “landscape space” to model space mapping. The possibility of hypothesis testing within this framework is proposed as a means of refining the mapping, with a focus on the differentiation of function within the model space. The approach combines elements of instrumentalism, relativism, Bayesianism and pragmatism while allowing the realist stance that underlies much of the practice of environmental modelling as a fundamental aim. It may be an interim philosophy that is awaiting developments in measurement technique to allow further refinement, but allows some coherent guidance about how to be specific in presenting predictions to end-users. 1. Why a new philosophy? It is quite possible to develop and use environmental models without any explicit underlying philosophy (although see, for example, Peters, 1991; Abbott, 1992; Rhoads and Thorn, 1996; Anderson and Bates, 2001, for discussions in different areas of environmental science). Many practitioners do, of course, although most might have the aim of developing and using models that are as “realistic as possible”, given the constraints of current knowledge, computing capabilities, observational technologies and available time. This type of implicit or pragmatic realism seems quite natural and appears to be intrinsic to modelling efforts as diverse as the coupled General Circulation Models (GCMs) being used to predict future climate change and modelling of the biogeochemical processes