A central, distinguishing feature of sustainable development as a policy paradigm is that it shifts the terms of debate from traditional environmentalism, with its primary focus on environmental protection, to the notion of sustainability, which requires a much more complex process of trading off social, economic and environmental priorities. Box 4 shows that the Brundtland definition is as much concerned with economic and social development as it is with environmental protection. Development is a process of transformation which, by combining economic growth with broader social and cultural changes, enables individuals to realise their full potential. The dimension of sustainability brings the recognition that development must also adhere to the physical constraints imposed by ecosystems, so that environmental considerations have to be embedded in all sectors and policy areas. Brundtland's unapologetic anthropocentrism, displayed in its concern for human welfare and the exploitation of nature, in preference to an ecocentric interest in protecting nature for its own sake, has opened up environmental politics to a wider audience. The promise of sustainable development is that it seems to offer a way out of the economy versus environment impasse; no longer need there be a trade-off between growth and environmental protection. Far from it: growth is seen as a 'good thing' because it enables less developed countries to develop and so improve the standard of living of their impoverished citizens, while the material quality of life in the affluent North can be maintained. All these benefits ... and environmental protection too!

Sustainable development, like beauty, is in the eye of the beholder; it therefore promises something for everyone. As Sharachchandra Lele has put it in 'Sustainable Development: A Critical Review', with just a hint of irony,

Sustainable development is a 'metafix' that will unite everybody from the profit-minded industrialist and risk-minimising subsistence farmer to the equity-seeking social worker, the pollution-concerned or wildlife-loving First Worlder, the growth-maximising policy maker, the goal-oriented bureaucrat and, therefore, the vote-counting politician. (from World Development, 19(6), pp.607-21)

These chameleon characteristics attract a wide array of supporters, but they also make sustainable development a highly contestable concept. Some aims appear radical: the elimination of poverty, the pursuit of global equity, reductions in military expenditure, wider use of appropriate technologies, democratisation of institutions and a shift away from consumerist lifestyles. Other themes, such as the acceptance of the capitalist economic system and the need for continued economic growth, seem to accept the status quo. The core principles also beg many hoary but unresolved political questions. For example, what are basic needs? Should they reflect the needs of citizens in the USA or Bangladesh? How far will the living standards of rich industrialised nations have to be adjusted to achieve sustainable consumption patterns? Different answers to these questions produce conflicting interpretations of sustainable development. These ambiguities have not been helped by the absence of a detailed framework in the Brundtland Report to help individual countries turn these broad principles into practical policy measures. Consequently, policy-makers have been able to pick and choose from the pot-pourri of often contradictory ideas in the Agenda 21 document while the endless stream of reports and books seeking to give flesh to this concept seems to have fuelled as much disagreement as it has encouraged consensus.

The proliferation of meanings is not just an exercise in academic or practical clarification but a highly political process of 'different interests with different substantive concerns trying to stake their claims in the sustainable development territory' (John Dryzek, The Politics of the Earth, 1997, p.124). As it has become more important, key interests have tried to define sustainable development to suit their own purposes. Thus an African government might emphasise the need for global redistribution of wealth from North to South in order to eliminate poverty, while a transnational corporation might insist that sustainability is impossible without vibrant economic growth to conquer poverty, stabilise population levels, provide for human welfare and, of course, maintain profit levels.

With so much ambiguity surrounding the meaning of sustainable development, there have been several attempts to construct typologies distinguishing different 'versions' of sustainable development. Most typologies identify 'weak' and 'strong' forms of sustainable development, with some normatively outlining a transition from weaker to stronger versions. Timothy O'Riordan (in Politics of Climate Change, O'Riordan, T., and Jäger, J. (eds.), 1996) provides an illustrative typology that distinguishes between levels of sustainability according to the way human and environmental resources are valued ranging, broadly speaking, along a continuum from technocentrism to ecocentrism. In very weak sustainability the overall stock of human capital and natural capital (i.e. natural resources and ecological processes) remains constant over time, but it allows for infinite substitution between the various kinds of capital so that the natural resources might dwindle providing they are compensated for by the extension of human capital. Weak sustainability accepts that certain critical natural processes that are essential to life, such as the ozone, tropical forests and coral reefs, need protection, but allows for substitution between other types of natural capital. Strong sustainability extends the definition of critical natural resources much further through the wider use of the precautionary principle. It anticipates that, as far as possible, the use of any natural resources should be compensated for through processes such as reforestation and recycling of products, or by social improvements such as community betterment or reduced inequality. Finally, very strong sustainability equates with radical forms of ecologism such as bioregionalism and deep ecology, and is characterised by a steady-state economy; local social, political and economic self-reliance and a redistribution of property rights through burden-sharing. Of course, these categories often overlap and there are many grey areas. Currently, most countries are only starting to move into the mode of 'very weak sustainability' and, at present, 'the modest aim must be to avoid obvious cases of non-sustainability' (ibid, p.147).

This typology of sustainability begs a question about the compatibility of sustainable development with ecologism. Many deep greens are understandably suspicious of a strategy that seems incompatible with the radical changes they demand. Thus, at a philosophical level, Dick Richardson condemns sustainable development for being a 'political fudge' that 'seeks to bridge the unbridgeable divide between the anthropocentric and biocentric approaches to politics' (from Susan Baker et al. (eds.), The Politics of Sustainable Development, p.43). From a political perspective, radical greens may regard sustainable development as compromised by its acceptance of capitalism. They argue that sustainable development is a contradiction in terms because much economic growth cannot be ecologically sustainable, so it is impossible to achieve sustainable development without replacing capitalism with a more decentralised, self-sustaining social and economic system. Uneasy about the compromises involved in sustainable development, some radicals, such as deep ecologists, prefer an oppositional strategy that stands aloof from any dealings with established political and economic institutions. However, this isolationism represents a minority position within contemporary green politics. Most green parties are firmly committed to the principles of sustainable development. The four pillars of the German Greens, for example, emphasise the centrality of development issues such as social justice, equality and democracy. It therefore seems reasonable to regard very strong sustainability, which clearly differs sharply from the other categories, as fitting within ecologism, with strong sustainability representing the boundary distinguishing ecologism from other doctrines.

Does it matter that so many versions of sustainable development exist and that there is so much disagreement about its meaning? Is contestability damaging? It could be argued that without a clear meaning almost anything could be said to be sustainable, leaving it as little more than an empty political slogan. A universally acceptable definition is needed, with a list of measurable criteria against which it would be possible to judge progress towards sustainability. Better to have clarity and risk losing a few unwanted adherents, than retain a vacuous 'anything goes' approach. Policy-makers would also benefit from a clear technical definition to help them implement sustainable development. Yet this perspective may undervalue one of the great strengths of sustainable development which is that the fluidity of the concept should be celebrated rather than condemned. Rather like other political concepts, such as democracy or justice, sustainable development is widely seen as a 'good thing' and has a generally accepted common-sense meaning within broad boundaries, but within those parameters there is deeper contestation around its constituent ideas. On this view the contestability of sustainable development has several virtues. Its 'all things to all people' quality has helped the message to resonate around the world and attract followers to the flag. In The Politics of Environmental Discourse: Ecological Modernisation and the Policy Process (1995, p.14), Maarten Hajer suggests that the 'coalition for sustainable development can only be kept together by virtue of its rather vague story-lines at the same time as it asks for radical social change', whereas insistence on a precise formulation of the term is more likely to deter potential supporters. Thus the 'motherhood' idea of sustainable development can win broader acceptance for radical ideas such as equity and democratisation.

	Thinking Point
	Sustainable development has been criticized for being a vague concept. List the pros and cons of this vagueness for policy-makers.

These debates can be a dynamic and positive feature of the incremental process of change. At the international level the sustainable development discourse has provoked fierce political struggles--particularly between North and South--that have pushed many environmental and development issues up the diplomatic agenda. International institutions such as the Commission on Sustainable Development (CSD) have helped drive the debate down to national and sub-national levels. The proliferation of sustainable development round-tables and Local Agenda 21 strategies has helped diffuse the idea throughout society and generated many practical initiatives. Even when governments are only paying lip-service to international commitments, they may indirectly initiate change simply by creating new institutions and promulgating different ideas that can disrupt established patterns of policy-making and alter the belief systems of policy elites. For example, when an unenthusiastic British government was obliged by its commitment to Agenda 21 to produce a sustainable development strategy (HM Government 1994), the process provided a window of opportunity for the Department of the Environment to bring environmental issues to the attention of other ministries, and may have contributed to the British government's decision to scale back its road-building programme.