SUSTAINABILITY AND CITIES - Comments on Peter Newman´s text on Urban Sustainability Henri Acselrad*

The idea of sustainability recalls the logic of practice, through which effects viewed as desirable are made to happen rather than a concept built to explain reality. Different meanings have been associated with this notion since the Brundtland Report introduced it to international public debate in 1987. Among these, special mention should be made to the idea of efficiency, by which the economic rationality should be extended to the "planetary non-market space" ; also the idea of scale limits to growth, which defends a quantitative restriction to the rates of economic growth and of its pressure over environmental resources; the idea of equity, which analytically combines principles of justice and ecology, suggesting that environmental degradation and social injustices have the same basic roots, supposed to be tackled together; the idea of self-sufficiency, which suggests to delink traditional societies from world market flows in order to ensure the community's capacity of self-regulating its local environmental resources. When applied to urban space, the idea of sustainability has also generated different representations of cities and different perspectives for city planning, from the management of risks and uncertainties to the increase of the capacity of urban structures to adapt itself to external shocks. What seems to organize analytically the discourse of "urban sustainability" is its division into two fields: one privileging a technical representation of cities by understanding this notion as a specific manner of managing the flows of energy and materials associated with urban growth; and another one defining the unsustainability of cities as the drop in the political productivity of urban investments; it means, by the "incapacity of urban infrasctructures to keep up with the rate of growth of social demands". In this case, the urban space would be placed explicitly as a political territory.

Professor Newman`s paper1 help us to better understand the current debate on urban sustainability, pointing out the main elements of convergence and of divergence among city planners. But we should perhaps try to look behind this debate, asking if there isn´t in fact different understandings concerning what is to be sustained in cities; in which social quality should we try to make cities to be sustained? Because cities may be seen to be sustained as a material structure, as the space of quality of life or as a political space where urban policies are legitimized.

So, these different representations of urban sustainability may point to the adaptive reproduction of urban structures focusing also alternatively on the readjustment of the technical system of cities, on the re-ensurance of citizenship principles to urban populations, or on the redefinition of the bases of legitimacy of urban policies. The representation that privileges the city as a technical-material structure (by far, the dominant perspective in the debate) suggest to sustain the city through the models of eco-energetic * Professor at the Institute of Urban and Regional Research and Planning of the Federal University of Rio de Janeiro (IPPUR/UFRJ)1 cf. Peter Newman, Urban Sustainability, paper presented at the Open Meeting of the Human Dimensions of Global Environmental Change Research Community, Rio de Janeiro, 2001.

efficiency or metabolic equilibrium applied to the materiality of the urban. The adaptive reproduction of urban structures that have the notion of quality of life as a reference supposes the city as a space of negative externalities to be tackled through the construction of rights, be it to healthy conditions of existence or to the symbolic dimensions of urban sites. In the idea of urban sustainability as the adaptive reproduction of urban policies, the city is seen as a space of construction of political pacts able to reproduce its legitimacy. But regarding these different representations of cities, to reduce the urban sustainability to its strictly material dimension would mean to disconsider the political content of urban spaces with its social complexity, currently responsible both for structural reproduction and innovation in the historical temporality of cities.

As professor Newman pointed out, there is a large consensus that the new principles of city planning must be holistic. Perhaps this generally accepted idea of a holistic framework should mean that the planning for urban sustainability must consider simultaneously all levels of cities as material structures, space of citizenship and place by excellence of politics. The september 11 tragic events of terrorism in New York seems to suggest that urban structures are intrinsically unstable when big global urban centers concentrate economic and financial powers in a very unequal world, in the absence of political institutions able to treat democratically the developmental and cultural conflicts. Because the big challenge is yet for us to find how to cultivate the city as a space by excellence for inventing social rights and developing a democratic culture.

The multiple discourses on urban sustainabilty Henri Acselrad*

I) Introduction

Different discursive matrices have been associated with the notion of sustainability ever since the Brundtland Report introduced it to international public debate in 1987. Among these can be mentioned the efficiency matrix, which aims to combat the waste of the material base of development by extending economic rationality to planetary non-mercantile space; the scale matrix which defends a quantitative limitation of economic growth and the pressure this exerts on environmental resources; the equality matrix, which analytically combines principles of justice and ecology; the self-sufficiency matrix, which preaches disassociating national economies and traditional societies from world market flows as an appropriate strategy to ensure the community's capacity of self-regulating the conditions to reproduce the material base of development; the ethical matrix, which includes social appropriation of the material world in a debate on values of good and evil by underscoring the interactions of the material base of development with the conditions for life to continue on the planet.

From the UNCED 1992 on, the idea of sustainability has been occupying a growing space in the debates on development. On the one hand, within developmentalist discourse - put forward by multilateral agencies, technical consultants and development ideologues - there was concern for correcting the course, greening projects, and adjusting decision-making processes. With adjustments, those actors believe, the development proposal can be recovered, its autophagic dimensions overcome, its permanence ensured, its relevance sustained. On the other hand, in the NGO field, in the midst of criticism of the limited content governments and official institutions have been assigning to so-called sustainable development, some regard sustainability as a new belief destined to replace the idea of progress, constitute "a new organizing principle of a people-centered development", and be able to "become the mobilizing vision of civil society and underlying principle guiding the transformation of societies' dominant institution" (PCDF, 1992). However, there is prevalence of recurrent interrogative expressions, in which sustainability is viewed as a "an evolving principle", an "infinite concept", that "few know what it is", and "that requires a lot of aditional research". Manifestations of frustrated positivism - sustainable development would be an objective fact, although it cannot yet be apreheended. But how to define something that does not exist? That when realized will undoubtedly be a social construction, and as such may encompass different contents and practices that claim its name. This clarifies why distinct representations and values have been associated to the notion of sustainability - they are discourses disputing the allegedly most legitimate expression - insofar sustainability is a notion one can utilize to actualize different representations and ideas.

* Professor at the Institute of Urban and Regional Planning and Research of the Federal University of Rio de Janeiro (IPPUR/UFRJ)

The alleged inaccuracy of the concept of sustainability suggests the absence of hegemony among the different discourses. Ecologists seem to be poorly positioned to dispute the discourse on this ground sown with the values of Fordist productivism and material progress. The sociopolitical view has been restricted to the NG0s' efforts, more specifically by prioritizing the equity discourse, particularly in the framework of international relations. However, the economic discourse has so far made better appropriation of this notion, even claiming its preexistence in Hicks' theory of capital and income.

Contrary to analytical concepts geared to explaining reality, the notion of sustainability is submitted to the logic of practices - it is linked to desired social results, to practical functions that the discourse intends to transform into objective reality. Such considerations reminds us of legitimization of practices and social actors. On the one hand, if sustainability is viewed as something good, desirable, unanimous, the prevailing definition will gain authority to separate, in its name, good practices from bad ones. Therefore, a symbolical struggle is underway to decide who has the authority to speak in terms of sustainability. For this, it is necessary to constitute the adequate audience, a field of efficient interlocution where approval can be met. In this manner, one will be able to speak on behalf of (and to) those who want the survival of the planet,sustainable communities, cultural diversity, etc. However, the struggle over such representation expresses the dispute of different practices and social formations, claiming to be compatible with or bearers of sustainability.

Nevertheless, to ascertain that some social practice is sustainable it is necessary to compare attributes of two moments in time: between past and present, present and future. As the comparison past-present in the framework of the current developmental model well expresses what is deemed unsustainable, the comparison present-future is adopted. Therefore, sustainable practices are those allegedly compatible with the future quality postulated as desirable. This relationship between a known present and an unknown and desirable future places the notion of sustainability in the field that some refer to as "teleologic causality" - "which has as sufficient cause for a behavior an occurrence that has in its description the requirement that another one, called its end, happens". That is, the cause is defined by its end; the order of the sequence of occurrences is built-in in the preceding condition defined as cause. Today is sustainable that set of practices that are bearers of sustainability in the future. Resorting to this "teleologic causality" is particularly doubtful when it implies rebuilding the present in light of allegedly future requirements. Historical experience has questionable examples of this political actualization of the future: "it is necessary to achieve economic growth in order to distribute", "stabilize the economy in order to grow later", "sacrifice the present to conquer the future", etc. Risks are even greater when one considers that those in dominant positions in the social space are also in dominant positions in the field of production of representations and ideas. If state and business - hegemonic forces in the developmentist project incorporate the critique of unsustainability of the developmental model, they also occupy a privileged position to provide the content to the very notion of sustainability.

However, this does not mean that the issue is settled once and for all. On the contrary, authority and legitimacy, decisive attributes for all those actors disputing the power to define what is sustainable, are also a function of the ways in which those actors elaborate

their alternative discourses on the issue, and of the relative strength they accumulate in the field of ideas.

In this paper we shall map out the major discursive matrices of urban sustainability and attempt to identify the inflections that the social agents who resort to this notion recommend for the social practices of building the space of cities. Because the future of the cities will to a large extent depend on the concepts that make up the project of the future built by the agents who are relevant to producing urban space.

II) Discourses of urban sustainability

Adding the notion of sustainability to the debate on urban development originates in the political re-articulations employed by a certain number of actors involved in producing urban space to lend legitimacy to their perspectives by revealing their compatibility with the proposals to make development durable, in accordance with the principles of Agenda 21 that resulted from the United Nations Conference on Development and the Environment. At the same time as we witness an "environmentalization" of the debate on urban policies, we also notice a movement in the opposite direction with the growing insertion of the urban discourse in dealing with environmental issues, either on the initiative of social agents of the city who incorporate the environmental theme under the argument of the substantial concentration of the population in metropolitan areas, or due to the very trajectory of growing urbanization of the environmental portfolio of World Bank projects.

We cannot fail also to associate resorting to the notion of urban sustainability to strategies to implement the city-corporation metaphor, projected on the "sustainable city" by some of the supposed attributes to attract investments, in the context of global competition. Guiding the cities towards a sustainable future means in this case "to promote productivity in the use of environmental resources and strengthen competitive advantages" (DURAZO,1997). Associated to a greater or lesser degree with the perspectives of "entrepreneurial" planning of cities, the idea of sustainability will offer the opportunity to legitimize an emerging ecocracy that is particularly favored by the creation of new governmental and regulatory instances aimed at dealing with the environmental question in general and the urban environmental question in particular.

In today's debate we are to find many logical connections between the reproduction of urban structures and their specifically material base. In particular we are to find three basically different representations of the city, to which there are corresponding and likewise different meanings of what is legitimately claimed to be capable of making urban integrity last.

II.1) Technical-material representation of cities

The first articulation associates the transition to urban sustainability with adaptive reproduction of urban structures focused on adjusting the technical bases of cities according to models of "eco-energetic rationality” or “urban metabolism”. In both cases the city will be seen in its material continuity of stocks and flows.

From the viewpoint of specifically material efficiency, the sustainable city will be that which for the same supply of services minimizes the consumption of fossil energy and other material resources and exploits local flows to the maximum, thereby satisfying the criterion of conservation of stocks and reduction of volume of waste. What prevails here is a technical-material representation of the city as a matrix composed of a vector of consumption of space, energy and raw-materials and a vector of production of waste. Reading the city as an open thermodynamic system will identify in the urban the privileged locus of the growing production of entropy, the emblem of the unlimited irreproducibility of the process of economic-material growth. In this light, urban unsustainability is a social expression of thermodynamic irreversibility. Based on a reading of the city as the place par excellence of the loss of the capacity to transform energy into work, it would fall to urban planning to minimize energetic degradation and slow down the course of irreversibility. Such a representation of the city points to new technical models for the urban founded on economic rationality applied to matter-energy flows. To soften the entropic impact of urban practices, it would therefore be convenient to adopt technologies that save space, matter and energy, and dedicated to recycling materials. The idea of eco-energetic efficiency aims consequently to broaden the field where economic rationality applies.

Eco-energetic efficiency can also be translated in terms of spatial distribution that is inadequate to the economy of means, that is, as the result of an improper locational distribution of population and activities within the urban space. Unsustainability would thus derive from the "increasing asymmetries between the spatial location of resources and the population, from the excessive pressures on the surrounding environment and on the regional ecological systems." In this case, unsustainability would result from the spatial redistribution of the technical pressure of populations and activities on the base of urban environmental resources. Here the Malthusian problem is written into the urban scenario, introducing the “hypothesis of the limit of urban capacity” and concentrating the focus on decentralization strategies, that is, distributing functions from the metropolis to the regions, from inner metropolitan areas to peripheral metropolitan areas, and from city centers to sub-centers.

The concept of sustainability as a progressive course towards eco-energetic efficiency is usually accompanied by the constitution of a social base to support projects of urban technical change via "environmental education", dissemination of an "ecological awareness", community recycling programs or by the engendering of a "recycling economy". The denial of any antagonism between the environment and the economy will also turn the search for urban sustainability into an opportunity to promote the symbolic potential of the market as an instance of city regulation. Because if for hegemonic thinking the future is one where market institutions are in full effect, steering cities towards a sustainable future means promoting urban productivity and strengthening competitive advantages.

Argumentative strategies of global order will often be brought into effect to promote innovations in the technical matrix of cities, either through the introduction of resource-saving urban technologies or through the spatial redistribution of population and activities: what's good for the planet is considered good for the city. The convergence between local urban sustainability and global sustainability is generally seen as a political simplifier,

seeing that on the local level those responsible for pollution and the political authorities are easily identifiable.

A counter-discourse, however, places global sustainability in opposition to urban local sustainability: what's good for the planet wouldn't be good for the city. On the one hand, scale economies of transportation, lighting and heating in concentrated cities reduce per capita consumption of energy by favoring strategies of global sustainability. On the other hand, the capacity of eco-systems to regenerate being constant per unit of territorial extension, concentrated cities suffer undesirable effects of the increase in territorial density of production of waste, thus compromising sustainability on the local level. In this case the search for eco-efficiency would be motivated by reasons relating to the urban proper rather than by reasons of a planetary nature. In both these cases, however, with convergence or divergence between urban and global sustainability, eco-efficiency will be legitimized as an axis of strategies of action and the market will be seen as its best instrument.

The idea of energetic unsustainability of cities is not restricted to the large metropoles of high demographic density, but also applies to the "fragmented" and "de-densified" city of "immaterial society": as Beaucire states, "the de-densification of men and the polycentric fragmentation of activities are costly in material resources and produce pollution and harmful effects" (BEAUCIRE,1995). He adds that "the fragmented and de-densified city is seen as a generator of very high energy consumption and costs of re-arranging of technical networks (water, electricity, telephones) and public services".

But the adjustment of the city's technical-material bases may alternatively obey models of urban metabolism, with an eco-systemic representation of cities made up of interactive movements of circulation, exchange and transformation of resources into transit. In this case the discourse on sustainability organizes itself by resorting to the biological metaphor of "resilience", which attempts to describe the adaptive capacity of "urban eco-systems" to overcome their condition of vulnerability to external shocks. In this type of representation, unsustainability would express the incapacity of urban structures to adaptively reproduce when the material conditions required for such reproduction break down.

The idea of urban metabolism refers to a model of equilibrium to be obtained through proper adjustment of the flows and stocks of matter and energy. The strategies to include urban development in the scientific framework of some objective knowledge about flows and supposed equilibria tend to materialize in a set of technical norms. Nonetheless, considering the uncertainties that prevail in knowledge about interactive processes so complex in their space-temporality, under each set of norms of "equilibrium" there will be implicit elements of values, preferences and "conventions" that are legitimized by science to lay the political bases for coordinating and stabilizing expected scenarios for action.

Processes of "eco-urban restructuring" can therefore be included in the mechanisms of "scientification of politics" through which the Scientific Ecology experts extend their field of action to the management of eco-systems and production of the rational foundations of territorial organization. The scientification of the debate on the supposed "ecological equilibrium" leads to the political need for an erudite management of territory, reflecting the fact that new institutionalized modes of production of knowledge are induced by

intensifying the relation between public bureaucracies and representatives of ecological knowledge.

Certain authors will nevertheless refuse to think of urban sustainability as a spatially circumscribed process that presupposes the irrelevance of the material flows that link cities to non-urban spaces. Taking the city as a consumer of natural resources and space for depositing waste, and considering too the complexity of urban-rural links, it may be claimed that "sustainable urban development and sustainable rural development cannot be separated". Some will even deny the possibility of conceiving "sustainable cities" and label as unrealistic the idea of restricting the scope of the flows of matter and energy demanded by urban development to the circumscribed space of the cities (PUGH,1996).

II.2) The city as a space of "quality of life"

A new technical matrix of cities is also entertained for reasons of "quality of life" - non-mercantile components of the daily existence of the citizens who make up the urban population, especially as regards the sanitary implications of urban practices. Models of asceticism and purity are evoked to question the technical bases of the urban - the urban more and more impregnates the city inhabitants with substances whose artificiality makes them harmful and toxic. Alternatively, the sanitary implications may be associated with collective representations of citizenship, where the liquid and gas emissions resulting from urban technologies are understood as a forced imposition of unsellable products of activities of mercantile production or of the mode of consumption of the products, notably motor vehicles.

Such representation of urban citizenship tends to spread over into the set of urban policies to justify structures that favor development of dialogue and negotiation, as well as putting into effect pacts that lend sense to the duration of cities not only in their materiality but also in terms of socio-political institutionality.

A notion of sustainability associated to the equity category refers not only to the materiality of cities but also to their character and identities, to values and legacies built through time. The perspective of lending permanence to the symbolic existence of sites - or sites that may eventually become symbolically "naturalized" - can be included both in strategies to strengthen the dwellers' feeling of belonging to their cities and to promote an image that marks the city for its biophysical, aesthetic or cultural assets in the broad sense so as to attract capital in the global competition through what some have described as a process that promotes the economics of beauty in the name of the beauty of economics.

The notion of urban sustainability can also coordinate the argumentative strategies of eco-energetic efficiency and quality of life in considering the urban form as a "determining factor of sustainability” (BREHENY-ROOKWOOD, 1996). The notion of "the compact city" would include, in the perspective of documents of the European Commission, for example, the attributes of "high density and mixed use, tending to present superior energy efficiency by reducing the distances covered, maximizing the supply of public transportation and providing residents with a better quality of life.” The formal

configuration of the metaphor of the compact city that would tend to be more accepted is that of the polycentric model in a network with diversified functions of the sub-centers well served by public transportation. Its capacity to conjugate efficiency in the use of environmental resources and quality of urban life is nonetheless not a point of consensus. Some will argue on the contrary that energy efficiency and quality of life are attributes of decentralized and not very dense cities, resorting as they do to local sources of energy and production of foodstuff in available rural land.

In both cases, the argument will be forwarded that the sustainable form should blend - even if in different scales - zones for work, residence and leisure, by reducing distances and "pedestrianizing" the cities so as to curb the mobility of energy, both of people and goods. From this point of view, eco-energetic efficiency and quality of life would result from the emergence of urban forms capable of expressing the desirably increasing existence of self-sufficient cities. The argument of the urban form thus articulates with the idea of urban self-sufficiency. In the case of sustainability of development in general, the self-sufficiency argument constitutes a criticism of free market and globalization; in the case of urban self-sufficiency, it is a question of an orientation, on behalf of the fight against the greenhouse effect and entropic processes, towards greater energetic and economic autonomy of the locations. A rejection of globalization of the cities will thus be justified from the point of view of the negative externalities and energetic dis-economies implicit in the intensification of flows that is characteristic of so-called "global cities".

II.3) The city as a space for legitimization of urban policies

As the materiality of cities is politically constructed, the modalities of their reproduction are also seen as dependent on the conditions that render their political presuppositions legitimate. The idea of sustainability is thus applied to the conditions for reproducing the legitimacy of urban policies. One speaks of the political feasibility of urban growth, that is, the conditions for political construction of the material base of cities. Unsustainability thus expresses the incapacity of urban policies to adapt the supply of urban services to the quantity and quality of social demands, causing "an imbalance between the daily needs of the population and the means of satisfying them, between the demand for urban services and the investments in networks and infrastructure" (GODARD, 1996).

It is believed that when urban growth is not accompanied by investments in infrastructure, the supply of urban services does not accompany the growth of demand. The lack of investment in maintenance of urban equipment will in turn accentuate the deficit in supply of services, which will return spatially in the form of socio-territorial segmentation among populations attended and not attended by such services. This process is thus expressed in the form of a "drop in the political productivity of urban investments", thereby increasing the degree of conflict and uncertainty in the process of reproduction of urban structures. The city's technical-material base is thus seen as socially constructed within the limits of elasticity of techniques and political will.

Unsustainability accordingly designates a process of destabilization of the bases of legitimacy of those responsible for urban policies, who can be reproved on the one hand for

their inability to lend efficiency to the administration of public resources or on the other hand for their unwillingness to democratize access to urban services.

The erosion of the legitimacy of urban policies may thus be based on insufficient adhesion to economic rationality, the supposed cause of the waste of the base of resources, or alternatively on the absence of priorities for the mechanisms that distribute access to such services. The material impact of the policies will consequently be contested either from the angle of waste of means or from the angle of socio-territorial concentration of benefits.

But social inequality of access to urban services is evoked to question the legitimacy of urban policies also in the so-called "immaterial cities", which apparently would be immune to undesirable pressures on flows of matter and energy. Beaucire claims that the spaces de-industrialized and de-localized by capital also end up void of their "urbanity", so that "social disqualification and environmental disqualification advance together to promote the rebirth of what was thought to be definitively over: physical insalubrity and a kind of economic and cultural ghetto within the cities, which are nonetheless penetrated by increasingly active technical networks" (BEAUCIRE, 1995). So it is believed that "the social and spatial allocation of the costs engendered by the crises of unsustainable development of the de-densified city will be a complicated affair, with the question of urban sustainable development running the risk of becoming first and foremost a social matter".

The crisis of legitimacy of urban policies may also be attributed to the inability to face technological and natural risks. From the perspective of equality, the culturally constructed risk will point to inter-temporal inequality of access to urban services, with the prevalence of the risks for the segments of the population that are less favored by the benefits of public investments or affected by technical negligence in disregarding specifics of the physical conditions of cities such as slopes, topographical accidents, natural drainage systems, unusual earth movements, renovation of top soil, cave-ins, erosion and silting. III) Conclusion

If for Isabelle Stengers the concept translates the power of the intellect to reach the essence of things (STENGERS - SCHLANGER, 1988), it also has the power to make representations objective and convey the ordering and classifying schemes of intellectual construction as being legitimate in concrete reality. Conceptual enunciation therefore also produces ordering, division and classification within the social world.

Chartier reminds us that "perceptions of the social are not neutral discourses” (CHARTIER, 1990). They produce strategies and practices that tend to impose one authority at the cost of others, legitimize reforming projects or justify individual choices and conduct. Consequently, "the schemes that generate classifications and perceptions, and which belong to each group or milieu, are true social institutions that incorporate in the form of mental categories and collective representations the demarcations of the social organization itself."

To associate the notion of "sustainability" to the idea that there exists a lasting social form of appropriating and using the environment that is offered by the very nature of biophysical

formations, for example, means to ignore the diversity of social forms of duration of the elements of the material base of development.

Placing the debate on sustainability outside the marks of ecological determinism thus implies removing non-differentiating representations of space and environment. This requires that the idea be questioned that space and environmental resources can have a single sustainable mode of use inscribed in the very nature of territory. So the non-deterministic perspective presupposes that the temporality of the elements of the material base of development is socially differentiated. In other words, that it be acknowledged that there are many ways of things to last, whether they be eco-systems, natural resources or cities. --------------------------------------------------------------------------------------------------------- Chart 1

DISCURSIVE MATRICES OF URBAN SUSTAINABILITY

1) Technical-material representation of the city

1.1. Model of eco-energetic rationality

1.2. Model of metabolic equilibrium

2) The city as a space of “quality of life”

2.1. Model of purity

2.2. Model of citizenship

2.3. Model of patrimony

3) The reconstitution of the legitimacy of urban policies

3.1. Model of efficiency

3.2. Model of equality-------------------------------------------------------------------------------------------------

The different representations of what urban sustainability have pointed to adaptive reproduction of urban structures focused alternatively on readjustment of the technical base of cities, on the principles that found the citizen-existence of urban populations, or on the redefinition of the bases of legitimacy of urban policies (see Chart 1). The representation that privileges reading the city as a technical-material matrix proposes recomposing the city based on eco-energetic efficiency or metabolic equilibrium models applied to the materiality of the urban. Reducing the durability of the city to its strictly material dimension tends to distort the political dimension of urban space by disregarding the complexity of the social fabric that is responsible both for reproduction and innovation in the historical temporality of cities.

The proposals for adaptive reproduction of urban structures that have the notion of quality of life as a reference are structured according to the model of purity, citizenship or equity. The city is thus seen as a space of negative externalities whose solution is to be found in the temporality of the process of construction of rights, whether rights to what will be considered healthy conditions of existence or rights to the lasting and beneficial use of the symbolic existence of urban sites. Thus the word citizenship returns to its place of origin - the city - to overlap the sense dominant up to now, referring to the Nation-State.

The proposals for adaptive reproduction of urban structures focusing on readjustment of the bases of legitimacy of urban policies seek in turn to refound the urban project according to the efficiency or equality model. In both cases the city will be viewed as a space of durable construction of political pacts capable of reproducing in time the conditions of its legitimacy. On thus promoting an "environmental" definition of the urban, the discourse of sustainability of the cities updates the struggle between technicalization and politicization of space, thereby incorporating - in the light of consideration of the temporality of urban practices - the confrontation between technicist and politicizing representations of time, in the midst of which may co-exist at the same time projects directed towards the simple reproduction of existing structures alongside strategies that cultivate the city as a space par excellence for inventing social rights and innovations. ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, BIBLIOGRAPHY

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