The Varieties of Sustainability Paul B. Thompson Paul Thompson was President of the Agriculture, Food, and Human Values Society during 1990 and 1991. He now directs the Center for Biotechnology Policy and Ethics, Institute of Biosciences and Technology, Texas A&M University, College Station, TX. He is also Professor of Philosophy and of Agricultural Economics at Texas A&M. His book The Ethics of Aid and Trade (Cambridge: 1992, Cambridge U. Press) reviews the alleged conflict of interest between U. S. farmers and efforts that would increase the productivity of agriculture in developing countries. ABSTRACT Each of four sections in this paper sketches the philosophical problems associated with a different dimension of sustainability. The untitled introductory section surveys the oft-noted discrepancies between different notions of sustainability, and notes that one element of the ambiguity relates to the different points of view taken by a participant in a system and a detached observer of the system. The second section, "Sustainability as a System Describing Concept," examines epistemological puzzles that arise when one attempts to assess the truth or falsity of claims that attribute sustainability or non-sustainability. In particular, such claims generally pr~sume bounded systems, but boundary conditions are value-laden. The third section, "Sustainability as a Goal Prescribing Concept," examines puzzles that arise in attempting to define sustainab ility in normative terms, ln particular, the question of whether sustainability is an intrinsic or instrumental value is examined. The final section, "Sustainability and Bliss," offers an analysis of the moral responsibilities that human beings have, given the fact that knowledge of conditions for achieving sustainability can never be complete. Since the earliest days of the environmental move- ment in America, scientists and philosophers have at- tempted to explain how the idea of natural or ecological balance can have normative significance. The question has often been framed in terms of duties to nature or to future generations, and these two ways of approaching the ethics of environmental issues have pointed philoso- phers toward a debate between ecocenlric and anthropo- centric ethical theories. The debate presents two alterna- fives for expressing the normative significance of eco- logical balance: (1) nature is valuable in itself, entailing at least some instances where human interests would be sacrificed to ecological values; or (2) ecological balance is important because of its instrumental value for human use, including future generations. This way of framing the issue has proved fruitful for the discussion of preserv- ing endangered species and for debates over the use of public lands for recreation, mining, or as preserves. It has, however, proved singularly unhelpful as applied to agriculture. The ecocentric position emphasizes value without respect to human use, and this approach to value has no application to agricultural systems beyond uni- versally deploring them or holding them in disdain (see for example, Diamond, 1987). Within agricultural ethics, the question of why natu- ral or ecological balance might have normative signifi- cance has not yet been widely discussed. The issues have focused almost entirely upon unwanted consequences of agricultural technology, consequences that impact water quality, soil fertility, food safety, and also the livelihood of the fanning community.1 These axe unintended conse- quences for humans, it should be noted, and there is nothing about these questions that directs us to under- stand how the ecology of agricultural systems might be of normative significance. The general question mightbe more precisely expressed as follows: why should hu- mans have a responsibility to preserve synergistic rela- tions among predators and prey, or between plants and 11