The reasons for the growing interest in the sustainability of farming systems can be understood with reference to the concept of sustainable development. The well known report "Our Common Future" of the World Commission on Environment and Development (also called the Brundtland Report) published in 1987, identified sustainable development as the central goal to be achieved by mankind in the future. The Commission defined sustainable development as the satisfaction of needs with intergenerational equity (WCED, 1987). The publication of this report marked the inception of several definitions for sustainable development.

Agricultural economists and natural resource economists became increasingly interested in defining "sustainable agriculture", a term which can be traced back to the early 1970s (Graham-Tomasi, 1991). The definition of sustainable development that was approved by the FAO Council in 1988 is as follows: the management and conservation of the natural resource base and the orientation of technological and institutional change in such a manner as to ensure the attainment and continued satisfaction of human needs for present and future generations (FAO, State of Food and Agriculture, 1989).

Sustainable development has been defined in a number of different ways. On the one hand, some experts believe that the process of substituting man-made capital for natural environmental stock can continue without any significant threat to sustainable development. Supporters of this view are said to be placing weak conditions on sustainable development. On the other hand, the supporters of placing strong conditions on sustainable development do not regard man-made capital as a substitute for natural environmental resource stock. According to these experts, the remaining environmental stock should, therefore, be preserved (Tisdell, 1996).

Norgaard has proposed five levels for addressing sustainability issues (Norgaard, 1988). On the first level, the local agricultural and industrial practices need to preserve the local resource base and the environment. On the second level, the question is addressed whether the region is dependent on resources from outside the region. On the third level, the definition of sustainability requires that the region be culturally sustainable in some sense. On the fourth level, the region’s contribution to global climate change should be considered. Finally on the fifth level, cultural sustainability should be analyzed on a global level, especially considering the possibility that all regions might destroy each other through war.

Lütteken and Hagedorn refer to Lynam and Herdt when they point out the necessity to take the spatial level, time and different dimensions of sustainability into account (Lütteken and Hagedorn, 1999; Lynam and Herdt, 1989). According to these authors, the three dimensions usually mentioned are the biological/physical, the economic and the social dimensions. However, an ethical as well as a global dimension is also of importance.

We see that different views on the sustainable development issue have been taken. As was mentioned in the introduction, the emphasis on looking at sustainable farming systems will be from the ecological and economic perspectives. The approach taken here will be pragmatic to a certain extent, with the aim of providing a basis for problem-solving research. The starting point of this approach might tend towards having strong conditions for sustainable development. Because strong conditions are quite limiting, however, one cannot claim that strong conditions for sustainable development are appropriate in all cases.