Defining and refining the concept of sustainable development has become a common exercise. Such an exercise, however, remains a necessary preface to an analysis which utilizes this term, because of the plethora of meanings and emphases, and therefore the diverse implications of this commonly stated objective. Sustainable development is most often defined as "development that meets the needs of the present without compromising the ability of future generations to meet their own needs" (WCED, 1987: par. 2.1). This definition leaves a good deal of room to manoeuvre: it does not specify whose model of development should be followed, nor who will determine the economic, social or biological needs of the present or of future generations.

In general terms, "sustainable development" is used here to imply a continued improvement in living levels, particularly those of the poor and of disadvantaged groups. In many situations in the Third World, improved living levels are dependent to a large extent upon increased consumption of resources. Therefore, this definition of sustainable development necessarily implies that present levels and methods of resource exploitation should not degrade the environment to the point that resource availability in the future will decline, unless this decrease in resource yields can be compensated through resource "imports". It is also important to recognize, however, that living levels also depend on environmental factors unrelated to economic or physical resource yields, including the availability of clean air and adequate living space, and, in many circumstances, people's ability to maintain a spiritual, cultural or aesthetic relationship with their environment. This definition, therefore, also suggests that ecosystem conservation plays a part in sustainable development. Thus the two extremes of the current usage are avoided: it is specifically not intended that "sustainable development" should imply that only those natural resources which can be shown to provide a positive yield in a benefit/cost calculation should be protected. Neither is it implied that the resources of the South should, in the name of the good of the planet, fall under the moral jurisdiction of the North.¹

Despite the range of meanings attributed to "sustainable development", it is important not to dismiss the concept as a fashionable yet vacuous fad. The very fact of the wide appeal of the concept means that it has had important implications for the direction that development efforts have taken, and for the programme of work on the environment currently gathering momentum in the development community, as well as on national and local levels. The current coincidence of interest in sustainable development emerges from developmentalists' increasing recognition of the importance of preserving natural resources if development is to continue; and conservationists' growing acceptance that, without development, preservation is not possible.² In addition, those concerned with local empowerment, indigenous people's rights, or other human rights issues have recognized that, because the environment is often a very local issue, sustainable development has useful connotations for them as well.

However, given that there are deeply entrenched differences in the understanding of sustainable development, the current unity of purpose in working toward this ill-defined goal is likely to dissolve as more concrete (as opposed to conceptual) decisions need to be taken, and trade-offs made. The alliance based on the flexible concept of sustainable development is not inherently stable or, indeed, mutually beneficial to its members, and will inevitably be strained as divergent interests become more clear (Hawkins and Buttel, 1990). However, because of the usefulness of the coalition itself in fostering dialogue and co-operation between the different groups, the concept of sustainable development serves a purpose, and should not be rejected either on the basis that it has been co-opted by mainstream economists or ecologists (Thrupp, 1989; Rees, 1990) or that it is too amorphous to be useful.

In defining sustainable development as continued improvement in the levels of living of the disadvantaged, and focusing on ways in which true local level participation (which includes the involvement of local people in defining the goals to be attained) can form the basis of more successful approaches to reach this goal, a range of important issues are raised. These include the roles of the state and the international development community in determining policy which affects the environment, the mechanisms by such policies are influenced, the impact of large-scale environmental destruction on the options available to small-scale resource managers, and the role played by systemic and structural factors in influencing the outcome of a range of environmental problems. These issues inform the argument of much of this paper, although their detailed and systematic analysis are beyond its scope. This approach produces fresh insights into a number of the standard interpretations of the sustainable development conventional wisdom, including the viability of traditional resource management systems, the dynamics of common property management, the relationship of population growth to environmental degradation, and the large-scale potential of small-scale popular environmental movements.

1 This is implicitly understood in some uses of the term sustainable development: at times the North seems to see itself as entitled to take measures to enforce environmental preservation without regard to the needs of the South - as, for instance, Northern writers commonly lament "our vanishing rainforests".

2 Although there remains as well a strong anti-growth trend of thought among more fundamentalist ecologists.