Agriculture, Ecosystems and Environment 86 (2001) 173–185 Assessment of the contribution of sustainability indicators to sustainable development: a novel approach using fuzzy set theory A.M.G. Cornelissen a,∗ , J. van den Berg b , W.J. Koops a , M. Grossman c , H.M.J. Udo a a Animal Production Systems Group, Wageningen Institute of Animal Sciences, Wageningen University and Research Centre, P.O. Box 338, 6700 AH Wageningen, The Netherlands b Department of Computer Science, Faculty of Economics, Erasmus University Rotterdam, P.O. Box 1738, 3000 DR Rotterdam, The Netherlands c Department of Animal Sciences, University of Illinois, Urbana, IL 61801, USA Received 6 April 2000; received in revised form 25 August 2000; accepted 20 September 2000 Abstract As a consequence of the impact of sustainability on agricultural production systems, a standardized framework to monitor sustainable development would have great practical utility. The objective of this paper is to introduce fuzzy set theory and develop fuzzy mathematical models to assess sustainable development based on context-dependent economic, ecological, and societal sustainability indicators. Membership functions are at the core of fuzzy models, and define the degree to which indicators contribute to development. Although a decision-making process regarding sustainable development is subjective, fuzzy set theory links human expectations about development, expressed in linguistic propositions, to numerical data, expressed in measurements of sustainability indicators. In the future, practical implementation of such models will be based on elicitation of expert knowledge to construct a membership function. The fuzzy models developed in this paper provide a novel approach to support decisions regarding sustainable development. © 2001 Elsevier Science B.V. All rights reserved. Keywords: Sustainable development; Sustainability indicators; Assessment; Fuzzy set theory; Agriculture 1. Introduction The impact of “sustainability” on development of national and international policy has increased over the last decade. Sustainability is now a core element of government policies, of university research projects, and of corporate strategies (Spedding, 1995; WRR, 1995; Graaf and Musters, 1998; Mebratu, 1998). Despite the variety of definitions and interpre- tations, sustainability consistently means, either ∗ Corresponding author. Tel.: +31-317-484626; fax: +31-317-485006. E-mail address: ton.cornelissen@dps.vh.wag-ur.nl (A.M.G. Cornelissen). explicitly or implicitly, “continuity through time”. Rather than referring to continuity per se, sustain- ability associates continuity to context-dependent economic, ecological and societal (EES) issues (e.g. Shearman, 1990; Brklacich et al., 1991; Neher, 1992; Heinen, 1994; Clayton and Radcliffe, 1996; Hansen, 1996; Vavra, 1996; Becker, 1997; Giampietro et al., 1997; Mebratu, 1998). “Agricultural sustainability”, which is sustaina- bility in reference to agricultural production systems, invokes concern that in the future, also in the near future, current agricultural activities might endan- ger the continuity of agricultural production systems (WRR, 1995). This concern is expressed through EES issues, which can range from meeting a need 0167-8809/01/$ – see front matter © 2001 Elsevier Science B.V. All rights reserved. PII:S0167-8809(00)00272-3