Sustainability may be regarded as one of the most challenging and, at the same time, most fuzzy contemporary paradigms. In the present study, referring to the history of other leading ideas, this confusion is identified as a typical feature of young paradigms with a particular danger of misuse and destruction of the idea. Requirements necessary to save and evolve the paradigm of sustainability are identified. It is shown that help cannot be expected in the phrasing of a generally accepted definition. As an alternative, it is proposed to focus on the assessment procedure, where quantitative or qualitative value measures of the paradigm are developed for particular situations. The present study intends (i) to clarify the logic and terminology of the assessment process in general, (ii) to provide an effective assessment concept for sustainability in the field of agricultural land-use, and (iii) to demonstrate possible perspectives for rural planning practices. The first part displays fundamental aspects of valuation theory. The methodology of explicit assessment is introduced and described as a heuristic procedure, evolving the meaning of a term or paradigm in a socio-cultural discourse and in relation with practical experience. In the second part, focusing on sustainability assessment, the terminology, steps and elements of the general assessment procedure are defined on behalf of the assessment of land-use sustainability as an example. The iterative procedure allows developing quantitative and/or qualitative value measures for particular situations. The central element of the method is a hierarchically structured collection of viewpoints, called checklist of criteria. In a holistic, comprehensive approach towards sustainability ('strong' sustainability), five principal criteria are recommended for consideration: (i) abiotic environment; (ii) biotic environment, including animal welfare; (iii) cultural values, defined as human emotional and mental well being and creativity of society; (iv) sociology; and (v) economy. To each principal criterion, a hierarchical list of important sub-criteria is added. For the project-specific selection of suitable sub-criteria guidelines are described in detail. The result is an individual assessment system adapted to the natural, cultural, political and economic basic conditions of a given project. In the third part, the example of a Swiss land-use planning project shows the implementation of the methodology in practice and its benefits, e.g., the improvement of the communication within the project, or the promotion of an effective, goal-oriented planning procedure, as a basic tool for valuation, communication, planning, implementation and monitoring of sustainability in the field of agriculturally based land-use systems. (C) 2000 Elsevier Science B.V. All rights reserved.
