Catherine Baumont

Jean-Marie Huriot

Jean-Marie Huriot

H Alexandre

Hight Frequency

Mean Reversion

J.-M Huriot

C Gnos

L Von Mises

Adolphe Landry

P Salmon

Sophie Béjean

Christine Peyron

Marie-Claude Pichery

C Laporte

Christian Michelot

Frédérique Perron

ECONOMIC GEOGRAPHY AND GROWTH Recent advances and new results

Two fields of economic theory have developed recently in parallel: on the one hand, economic geography aims to explain the formation of a heterogenous space, i.e. how the agglomeration of households and firms determines differentiated regions, urban structures or urban systems; on the other hand, theories of endogenous growth propose new views on growth mechanisms which invalidate the traditional convergence rule. These theories are based on common foundations such as increasing returns, spatial externalities and monopolistic competition. We examine here in some detail how the spatial dimension is implicit in endogenous growth theories. We emphasize the whys and wherefores of the combination of these two theories, showing what new results can be derived and what the limits of this new approach are. RESUME : Deux domaines de la théorie économique se sont récemment développés en parallèle. D'un côté, l'économie géographique cherche à expliquer la formation d'un espace hétérogène, c'est-à-dire à montrer comment l'agglomération des ménages et des firmes détermine des régions différenciées, des structues urbaines et des systèmes de villes. De l'autre côté, les théories de la croissance endogène proposent des visions nouvelles des mécanismes de croissance qui invalident les résultats classiques sur la convergence. Ces théories reposent sur les mêmes fondements : rendements croissants, externalités spatiales et concurrence monopolistique. Dans ce papier, nous examinons précisément comment la dimension spatiale est implicitement présente dans les théories de la croissance endogène. Nous analysons les raisons et les modalités de la combinaison de ces deux théories en montrant d'abord quels nouveaux résultats on peut en tirer et ensuite quelles sont les limites de ce te nouvelle approche.

increased the size of the market. It can be deduced that this facilitated the division of labor, and therefore industrialization. [START_REF] Bairoch | Cities and Economie Development: from the Dawn of History to the Present[END_REF] showed clearly that the origin of cities the world over lay in the production of an agricultural surplus, and therefore in the first signs of economic growth.

He further emphasized the reciprocal link in the key periods of urban development between urbanization and growth, by showing that industrialization promotes growth and that in return growth favors urbanization. It is not a matter of determining the direction of straightforward causality but of finding the rationale behind circular causality.

Theoretically,

space and growth are now brought closer through the recent developments in endogenous growth theory on the one hand and in the theory of the formation of space on the other. Convergence of the two approaches is based on their common break from the Arrow-Debreu model.

Microeconomic theory is based largely on the Arrow-Debreu competitive general equilibrium model and in particular on its assumptions of constant returns (or at least of non increasing returns) and of pure and perfect competition. Spatial theory was able to develop in line with these assumptions as long as it was confined to an analysis of partial equilibrium, with the location of at least one category of economic agents or activities being

given. But it failed to explain the simultaneous location of different agents (firms and households) in a spatial general equilibrium model or model of formation of space. It was thus shown that the main obstacle to the complete treatment of space in economic theory until a recent date was the incompatibility between space and competition [START_REF] Thisse | Espace et concurrence[END_REF][START_REF] Krugman | Development, Geography, and Economic Theory[END_REF].

The solution of new problems raised by this general spatial equilibrium assumed extension beyond the theoretical framework of the Arrow-Debreu model, in particular through the adoption of increasing returns and of a monopolistic competition structure. The contribution of [START_REF] Dixit | Monopolistic Competition and Optimum Product Diversity[END_REF] proved essential to the emergence of models of economic geography or of the formation of cities.

Growth theory overcame an obstacle of the same nature. The traditional neo-classical theory of growth posited constant returns to scale and decreasing marginal productivity.

Sustained growth cannot be achieved under these postulates in the presence of an essential fixed factor (i.e. one whose absence prevents any output). Growth then can only be the outcome of an exogenous technological change, which it is impossible to remunerate given the theorem of exhaustion of the product. Once again only increasing returns can overcome this obstacle. Here the break from the Arrow-Debreu model leads us to theories of endogenous growth.

The break is therefore much of the same nature in the theory of the formation of space and in endogenous growth theories. But the repercussions are greater than a simple change in a technical assumption. It entails fairly radical changes in the way we represent economic mechanisms. Both theoretical fields share common ground.

• They are based on similar theoretical concepts: with the transition from constant returns to increasing returns, a key role is ascribed in both cases to monopolistic competition and spatial externalities, which indicates the intention to include all market and non-market interactions between households and between firms.

• They seek to endogenize (i.e. to determine by internal and self-sustaining forces), growth mechanisms (i.e. the accumulation of economic activities over time) in the one case, and mechanisms of agglomeration and concentration (i.e. spatial accumulation of economic activities) in the other case.

• They attribute durable consequences to exogenous shocks or to even small differences in initial conditions through the implementation of cumulative processes.

• They thus recognize the necessary heterogeneity of economic phenomena through diverging and irreversible processes of change: for growth theories this is the result of non convergence and for location theories the recognition of unequal distribution of economic activities in space; these changes exhibit threshold effects and bifurcations of paths.

• They ascribe an important role to historical time: in both approaches « history matters », even if it is often only through the initial conditions.

• Finally, they bring out multiple equilibria which may be more or less stable.

However, these common foundations are not sufficient to legitimize integration between spatial analyses and growth theories. Such integration is only founded if it leads to a real advance in understanding the self-sustaining phenomena of growth and agglomeration, i.e.

if it can change earlier results or produce new findings and thus explain phenomena that could not be explained previously.

Nations, regions, cities and growth

The common ground referred to above shared by the theory of formation of space and new growth theories characterizes in particular the analyses that ascribe an essential role to economic mechanisms capable of sustaining endogenous processes.

The geographical principles that we retain derive from two types of spatial analysis. On the one hand, there are theories of the formation of regional space based on the inter regional equilibrium model developed by Krugman in economic geography (1991) and much extended since [START_REF] Helpman | The Size of Regions[END_REF][START_REF] Krugman | First Nature, Second Nature, and Metropolitan Location[END_REF][START_REF] Martin | Industrial Location and Public Infrastructure[END_REF]Venables, 1995). On the other hand, there are theories of the formation of urban space based on urban equilibrium models developed by Fujita [START_REF] Fujita | A Monopolistic Competition Model of Spatial Agglomeration: Differential Product Approach[END_REF][START_REF] Fujita | Urban Economic Theory -Land Use and City Size[END_REF][START_REF] Fujita | L'équilibre spatial -L'interaction entreprises ménages[END_REF][START_REF] Fujita | Multiple Equilibria and Structural Transition of Nonmonocentric Urban Configuration[END_REF][START_REF] Ogawa | Non-monocentric Configuration in a Two-dimensional Space[END_REF] or on inter-urban equilibrium models developed by Fujita, Krugman, Henderson (Fujita, Krugman, 1995;[START_REF] Henderson | The Sizes and Types of Cities[END_REF][START_REF] Henderson | Systems of Cities and Inter-City Trade[END_REF]. It is interesting to observe that the adoption of a common question -that of the formation and development of agglomerations -has brought together spatial theoretical analyses that were heretofore very far apart: on the one hand, theories of inter-regional equilibrium derived from new analyses developed in international economics [START_REF] Krugman | Trade, Accumulation and Uneven Development[END_REF][START_REF] Helpman | Market Structure and Foreign Trade[END_REF] and therefore more part of macroeconomics and on the other hand analyses of new urban microeconomics.

More generally, comparison of these two types of spatial analyses and endogenous growth models leads us to focus on several scales of analysis: the international scale [START_REF] Grossman | Innovation and Growth in the World Economy[END_REF] or national scale [START_REF] Lucas | On the Mechanisms of Economic Development[END_REF][START_REF] Romer | Increasing Returns and Long-Run Growth[END_REF][START_REF] Romer | Endogenous Technological Change[END_REF] for the endogenous growth model and the regional or urban scale for spatial analyses. The relevance of a theory of regional endogenous growth that borrows from both these strands must then be examined. This question is fundamentally linked to the scale of analysis used:

the region. The theoretical and empirical relevance of this choice must be justified and two arguments seem essential here. On the one side, the specific nature of inter-regional studies compared with international studies must be shown. On the other side, it must be shown why it is important to integrate the specific features of urban analyses into regional economic studies.

From nations to regions

Location theories of economic geography relate two spatial entities that are reduced to 'points' and which some authors explicitly call regions, in reference to an infra-national economic area. Other authors, though, explain that the theories could equally well apply to cities, regions or nations [START_REF] Helpman | The Size of Regions[END_REF]. In such cases, the specific feature of economic geography models compared with international trade models does not lie in the choice of a particular economic space. Nonetheless, the regional scale means trade between economic areas may be characterized in a different way. Already within an inter-regional space, monetary unity is effected which eliminates any reference to exchange rates. Then, the mobility of labor is not subject to any institutional constraint and can only be limited by individuals' economic decisions. Furthermore, trade in at least one type of good between regions is subject to transportation costs. Finally, as regions do not have absolute institutional and economic independence with regard to the nation, they may be dependent on a national public policy.

The more or less perfect conditions of mobility of factors and the variable level of trading costs between regions are so many forces that favor and/or hamper the concentration of economic activities at a given point of space. From there, economic geography models seek to explain the uneven distribution of economic activities within a single nation. If we are to analyse the economic growth of regions, we need to study how the uneven concentration of economic activities can influence the growth patterns of regions and what the consequences are for the economic growth of nations.

In this perspective, the regional scale is a refinement of the analysis of the economic growth of nations.

The regional dimension breaks the impression of economic homogeneity of the nation.

It is not true that all the regions of a country are equally endowed with skilled labor, or research centres or producer services or financial trading centres. Empirical studies often reveal a close correlation between the geographical distribution of these economic criteria and the level of economic growth of the regions [START_REF] Paelinck | Macro, Sectoral, Regional Policies and Regional Growth[END_REF][START_REF] Hansen | Do Producers Services Induce Regional Economic Development?[END_REF][START_REF] Catin | Economies d'agglomération et gains de productivité[END_REF][START_REF] Capron | La dynamique de croissance des régions en Europe[END_REF][START_REF] Camagni | Changement structurel et croissance de la productivité dans les régions européennes[END_REF]. But it is also true that the economic performances of a nation are often dependent on the economic performances of just a small number of its regions, and precisely the ones that concentrate the preceding economic criteria. Consequently, national or regional analysis of growth cannot lead to the same results. To understand this, we can examine the following simplified case where it is assumed that the rate of growth of the economy is an increasing function of the quantity of a factor x. Let us consider two nations each of them made up of two regions. Each region is characterized by the same mean national level x of factor x. The two nations therefore logically have the same rate of growth. Only the same mean national level x hides two different regional situations. In one of the nations, the factor is evenly distributed: both regions have a level x of factors and therefore the same rate of growth. However, in the other nation, the factor is more concentrated in one region and so regional growth is unequal too: a higher rate of growth could be expected in the region with the higher x factor. It follows that the rate of growth of this nation may be higher than that of the 'homogeneous' nation. Thus, the regional scale does not lead only to different geographical distributions of growth within nations, it can also explain why nations that are equally endowed in factors may have different rates of growth.

The urban dimension

Location theories have opened up the black box of agglomeration by specifying the number and nature of economic activities present. They also hepl us to understand that the concentration of economic activities produces economies of proximity and is an effective answer to conditions of production (manufacturing sectors with increasing returns) and coordination constraints between economic activities (vertical linkages between sectors, matching constraints on commodities markets or on the labor market, etc.). But these agglomerations remain reduced to points. They have no substance, i.e. the spatial organization of economic activities within the agglomeration is of no concern. That also implicitly means that it is assumed that this spatial organization has no impact on the economic organization of activities. By contrast, the new microeconomic theories of the city are better able to specify the conditions under which agglomerations operate and develop.

They provide further lessons about the role of geographical factors in economics.

In urban models, we are interested in the formation, organization and evolution of urban structures. We seek out the optimal economic conditions for the operation of agglomeration which means determining the optimal spatial organization of urban activities and the optimal size of cities. These models take into consideration the effects of spatial accumulation of economic activities on the operating costs of the agglomeration. Thus, as the size of the agglomeration increases, intra-urban travel becomes more expensive, while the stronger competition for land use among activities produces tensions on the land market.

New dispersion (or centrifugal) forces, engendered by spatial conditions of operation of the agglomeration arise. Accordingly, the ever increasing concentration of activities in space is no longer automatically an efficient form of economic organization.

Integration of the principles used by new urban microeconomic theories in inter regional equilibrium models leads to the following points.

• There are dispersion forces inside the agglomeration, i.e. there are location costs of economic activities. These are land costs, congestion costs or more generally all costs related to the actual workings of the agglomeration. These costs influence households' or firms' mobility between regions.

• Spatial organization, or more simply the size of the agglomeration, influences these costs. It follows that there is an optimal agglomeration size beyond which the dispersion forces get the upper hand over agglomeration forces. More generally, there is a limit to the concentration of economic activities and ever greater concentration is not necessarily preferable.

• The actual dynamics of the forces produced by agglomerations can be viewed as a function of the quantity or even the nature of economic activities which develop and concentrate there. But this function needs to be defined more precisely.

• By extension, the effects of the spatial concentration of economic activities on the operation of the economy seem to be vehicled by urban structures. Cities become the seat of mechanisms of economic development and growth. This phenomenon can be observed at national level in the role of capitals or major national metropolises. But it is also true at a global scale where it is considered that the globalization of the economy is orchestrated almost exclusively by the decisions made and the economic relations in only three world cities: New York, Tokyo and London [START_REF] Sassen | The Global City[END_REF].

By taking the analysis of economic phenomena to the regional scale and using the principles of spatial and urban analysis, the effects of spatial concentration of activities on the economy can be better investigated. In particular, this provides better understanding of the mechanisms of economic growth.

The geographical conditions of growth

It is assumed here that the formal and conceptual parallels between growth theories and spatial theories hide in fact fundamental and inescapable economic principles the most remarkable of which is spatial concentration.

Thus, the phenomena of increasing returns are only the sign of economic indivisibilities [START_REF] Koopmans | Three Essays on the State of Economic Science[END_REF]. It is the indivisibilities that justify the economic efficiency of grouping activities and individuals in a single place and therefore the uneven distribution of activities in space. Indivisibilities require coordination between complementary factors or activities and physical proximity, i.e. spatial concentration, can reduce such coordination costs. Thus it is more efficient to bring workers together and bring raw materials to a single place of production. Economic relations between different sectors are less expensive when the different firms are close to each other. Transactions on the labor market or the markets for goods and services are more efficiently conducted when suppliers and demanders are close together. Generally, the quest for proximity is an economic response to the phenomena of increasing returns.

But at the same time, agglomeration promotes the emergence of increasing returns that are external to firms. These external effects are widely used in endogenous growth theories to explain how the dynamics of factor accumulation can support economic growth.

Reference is often made to knowledge spillovers related to the circulation of information and know-how or transaction cost economies. It seems that most of these external effects are agglomeration economies (Baumont, 1997) arising from spatial closeness between individuals and economic activities. Urban structures play a leading role in growth dynamics [START_REF] Lucas | On the Mechanisms of Economic Development[END_REF]Pavilos and Wang, 1993;[START_REF] Duranton | Economie géographique, urbanisation et développement[END_REF]. A number of studies emphasize the role of cities in productivity gains [START_REF] Camagni | Principes et modèles de Véconomie urbaine[END_REF]Glaeser, 1994;Glaeser, Kalla, Scheinkman, Schleifer, 1992;[START_REF] Rauch | Productivity Gains from Geographic Concentration of Human Capital : Evidence from the Cities[END_REF].

More specifically, the role of urban agglomerations in growth mechanisms involves two effects. The first is related to the production of agglomeration economies that we have just spoken of. The second comes from the nature of urban economic activities. Economic activities that provide growth as evoked in endogenous growth theories accumulate in cities:

training and education, communication infrastructures, innovative sectors, producer services, etc.

Phenomena of spatial concentration thus explain how some economic parameters, common to growth theories and location theories, bring about growth. This is the case of preference for variety, for instance. Spatial competition leads to the concentration of the production of differentiated goods (d'Aspremont, Gabsziewicz, [START_REF] D'aspremont | On Hotelling's Stability in Competition[END_REF] and the agglomeration responds by a market size effect to the supply of differentiated goods [START_REF] Krugman | Increasing Returns and Economic Geography[END_REF]. The agglomeration becomes the place where preference for variety is expressed and the greater this preference, the greater the spatial concentration.

This is also the case with vertical linkages between sectors since spatial concentration means transaction costs can be reduced. The better integrated the economic sectors and the more the agglomeration of diversified activities will develop.

Consequently, agglomeration may be viewed as a growth factor in its own right as it is a combination of activities and mechanisms necessary for growth. It becomes logical to include dynamics of spatial accumulation of economic activities in endogenous growth models.

We must now show how and for what purpose growth is introduced into spatial models.

Growth in space

Preliminary remarks

Growth is not totally absent from space formation models. However, location dynamics which characterizes such models is not true growth dynamics.

Spatial dynamics is dynamics of the location of a given and fixed set of units, i.e. for an economy of a given size. What remains fixed may be, say, the number of workers in Krugman-type models [START_REF] Krugman | Increasing Returns and Economic Geography[END_REF][START_REF] Fujita | When is the Economy Monocentric?: von Thünen and Chamberlin Unified[END_REF] or the number of households and firms in the model of [START_REF] Ogawa | Non-monocentric Configuration in a Two-dimensional Space[END_REF]. The status of the total number of good varieties, i.e. the number of firms in the monopolistic competition sector, is less obvious. It is usually fixed but may be determined endogenously depending on the other parameters of the model [START_REF] Fujita | When is the Economy Monocentric?: von Thünen and Chamberlin Unified[END_REF]. Growth dynamics is on the contrary that of exogenous or endogenous change in the number of such units.

Of course, spatial dynamics does itself generate differential growth, but only subsequent to the spatial movement of production units. For example, equilibrium of uniform distribution of production units of a continuum is unstable: the least disturbance caused by the movement of a single firm or the creation of a small spatial heterogeneity causes a cumulative concentration movement in one or other of two regions or toward a center. Some places fill up, others empty.

As for comparative statics analysis, even if it introduces variations in certain size parameters of the economy, such as the number of workers, it can only indicate the marginal effects of variation of such parameters.

There is a need to examine what happens in response to an ongoing and non infinitesimal variation in factors liable to represent growth in the size of the economy. True growth dynamics must be added to the spatial dynamics of space formation models to see how the former affects the latter. This can be done by integrating exogenous or endogenous growth into a space formation model.

Exogenous growth in space

Exogenous growth may be integrated in several ways. We shall look at two examples here.

• The model of [START_REF] Anas | On the Birth and Growth of Cities: Laissez-faire and Planning Compared[END_REF] introduces regular exogenous growth of the total population in a model of an equilibrium system of cities. It investigates how, during this growth stage, there is a shift from one-city equilibrium to two-city equilibrium. More specifically, two cities may potentially be located one at either end of a linear space. The agglomeration force is formed by a Jacobs-type externality: in each potential city, the output of each worker is an increasing function of the total number of workers in the city.

A negative congestion effect acts as the dispersion force.

Under these circumstances, the optimal size AZ* of a city can be determined. As long as the total population is less than this value, the only stable configuration is that of a single city, because location effects are dominant. As the population increases, the configuration becomes increasingly unstable because of the dispersion forces: a very small movement of population is capable of giving rise to a second city.

This type of result is, however, not very different from the bifurcations characterizing many space formation models, in which, for example, there is a shift from a monocentric arrangement to a pericentric configuration when the key parameters cross a certain threshold.

• The Fujita and Mori model (1994), of the Fujita-Krugman type, investigates the formation of new cities in the context of exogenous progressive growth of population in a closed economy. It is shown, in particular, that in the vicinity of the existing city or cities, the agglomeration effect (from the increased variety of products with population) is strong enough to prevent the rise of new cities. Consequently, new cities appear only at a certain distance from such cities. This is a good illustration of the spatial nature of agglomeration effects. Advantages related to concentration fade with distance. A shadow effect occurs close to an agglomeration preventing the formation of other agglomerations. A regular increase in population entails the formation of a fairly regularly spaced system of cities. In this context, the agglomeration force is therefore concomitantly a force of maximum dispersion of agglomerations. This is consistent with the results of [START_REF] Arthur | Silicon Valley Locational Clusters: When do Increasing Returns Imply Monopoly[END_REF] and [START_REF] Krugman | The Self-Organizing Economy[END_REF].

Endogenous growth in space

Sources of growth are now internal. The standard models are those of Englmann and Walz and of Walz; that of Martin and Ottaviano with global spillovers picks up on ideas fairly similar to the model of Walz; that of Kubo provides an interesting variation.

• The models of [START_REF] Englmann | Industrial Centers and Regional Growth in the Presence of Local Inputs[END_REF] and of [START_REF] Walz | Keynésienne en raison de sa volonté de se démarquer le moins possible, dans ses hypothèses et dans ses outils[END_REF] are considered here as standard models as they are based on Romer-type growth [START_REF] Romer | Endogenous Technological Change[END_REF] and on Krugmantype spatial dynamics [START_REF] Krugman | Increasing Returns and Economic Geography[END_REF][START_REF] Krugman | First Nature, Second Nature, and Metropolitan Location[END_REF]. In that they are the first steps toward the attempted synthesis of Krugman and Romer by Martin and Ottaviano (1996b).

Space in these models is formed by two point-shaped regions. the region where firms in the sector are already highly concentrated. The perfect circulation of knowledge is a further endogenous factor of dispersion in both models.

On these foundations, from an initial situation defined essentially by regional endowments in immobile factors and/or immobile intermediate goods, comes spatial dynamics upon which is superimposed an endogenous growth process, i.e. a regular and self-sustaining increase in the variety of intermediate goods.

As in the well-accepted results of economic geography, the initial distribution of fixed factors plays an important part. However, endogenous growth factors may reinforce or refine these results.

In the model of Englmann and Walz, a local knowledge externality reinforces the concentration process: any initial inequality leads to regular growth of a regional system where all R&D and all the production of intermediate goods and manufactured goods is concentrated in a single region.

In the case of global externalities, several equilibria are possible. We should stress that the existence of a global knowledge spillover (source of endogenous growth) may account for a more or less uneven distribution of production activity between regions (one region is comparatively, but not entirely, specialized in the production of the manufactured good).

• The first attempted model by Martin and Ottaviano (1996a) fits into the same approach to some extent.

The model includes two regions, North and South, which are identical except for the initial stock of human capital (the North being richer in human capital than the South) and three sectors manufacturing a numeraire good, a set of differentiated goods with increasing returns, and ideas for new varieties of differentiated goods (R&D), respectively, knowing that each idea corresponds to a unit of human capital, or to a variety of good, i.e. to a firm.

Endogenous growth is apparent here again in growth in the number of varieties of goods, sustained by the falling costs of producing new varieties.

Martin and Ottaviano, like the previous authors, distinguish the case of global and local knowledge spillovers: the cost of a new idea (new variety of goods) in one region falls with the stock of human capital (of varieties of goods) to be found in both regions or in that region alone. For the time being, we shall concentrate on global spillovers only.

Two opposing effects are at work: (1) low capital location attracts firms as they find less competition there;

(2) because of the greater capital, therefore of higher income, the other region attracts firms seeking to benefit from returns to scale by location close to 'affluent' markets.

The usual results of economic geography may be altered: strong growth, by creating new firms, increases competition and reinforces the first effect entailing a relative relocation movement in the initially poorer region. This movement can, however, be countered by a substantial fall in transportation costs.

• The model of Kubo (1995) pinpoints an interesting effect. Kubo moves away from Romer as he does not identify an R&D sector. Endogenous growth is sustained by a process of capital accumulation generated by profit. Accumulation of capital in a region has two effects: it reduces production costs in that region (economies of scale) and in the other region (regional external economies).

Different spatial configurations arise depending on the relative intensities of these two effects in the two regions. When effects that are internal to the region predominate everywhere, we find Krugman's core-periphery type configurations. When external effects win out in both regions, there may be growth with two regions of different and stable industrial sizes, with the more industrial region being the one where the differential between internal and external economies is greater. The mixed case, where internal effects predominate in one region and external effects in the other, is more complex and the initial size of the region plays a decisive role in the final configuration.

Thus, here again, growth changes the form of spatial equilibria that can be expected.

Growth, agglomeration and circular causality

The endogenous nature of growth and of agglomeration is engendered by their own circular causality. A new form of circular causality will now explain the self-sustaining process linking growth and agglomeration. An attempt is made to show how endogenous growth gives rise to certain spatial configurations which in turn act on the rate of endogenous growth. Apart from its methodological interest, this approach leads to new results concerning the consequences of the regional integration processes.

Here we come upon a new category of models, which is still little developed and we shall cite only the contributions of Martin andOttaviano (1996a, 1996b). The first of these models gives an outline of interdependence between growth and agglomeration when knowledge spillovers are local. The second generalizes the circular causality to the case of global spillovers.

Local knowledge spillovers

Let us return to the first model by Martin and Ottaviano (1996a), this time with local spillovers.

If the North has more idea capital than the South, income is greater, and therefore the market larger, and therefore more firms with increasing returns tend to locate there.

Consequently, the cost of R&D is lower in the North and the entire R&D sector locates in that region, fully determining the growth rate and therefore the entry of new firms, some of which, depending on parameters, locate in the South because there is less competition there.

Thus, the greater the concentration of firms in the North, the greater the external effect on R&D costs, the higher the global growth rate, the more new firms there are, the more relocations there are to the South if transaction costs are low.

This analysis entails an important consequence for the effects of commercial integration, i.e. of a fall in transportation costs. Low transportation costs are associated with greater concentration in the wealthy region; in this case, firms can locate close to large markets and export to the South. Thus a fall in transportation costs or liberalization of trade implies a higher growth rate. Thus we can predict a positive effect of commercial integration on the growth rate via its impact on location.

For economic geography, commercial integration implies, at least at the outset, relocation in the North. But many counter examples are observed. This contradiction is removed by introducing growth dynamics into economic geography. Commercial integration then has two effects: (1) increased concentration in the North;

(2) increased creation of new firms via the effect on the growth rate, some of which locate in the South.

This second effect, which is missing from economic geography models, explains how there can be an increase in relocations in the South after commercial integration.

5,2. Global knowledge spillovers

The second model of Martin and Ottaviano (1996b) takes up the same ideas generalizing circular causality between growth and agglomeration.

By concentrating on the global spillovers alone, the pure effects of global growth can be emphasized. The model clearly shows that growth is an agglomeration factor and then in return, agglomeration is a growth factor.

Growth is a sufficient cause of agglomeration, as it gives rise to agglomeration even in the absence of the usual causes which are migrations of workers in Krugman's model (1991) or vertical inter-sectorial linkages within the differentiated manufacturing sector of Venables' model (1996). Here, workers are immobile and vertical linkages are between the manufacturing sector and that of R&D.

The reciprocal effect of agglomeration on growth is borne by a new linkage compared

with the authors' first contribution: the introduction of intermediate consumption of differentiated goods by R&D. Accordingly, the R&D sector is affected by two types of externality: (1) a pecuniary externality from the vertical linkage between the R&D sector and that of differentiated goods; the cost of innovation is lower where the larger number of firms is located because if there are transportation costs, the input in differentiated goods costs less: concentration promotes innovation and therefore growth;

(2) a global technological spillover, a classic factor of endogenous growth: the cost of R&D depends on past innovations through its consumption of differentiated goods; but here the effect may be positive or negative depending on the value of preference for variety.

There is an equilibrium of equal distribution of all activities between the two regions, but it is unstable. Let us assume one instance of (exogenous) relocation of at least one firm from South to North. The cost of R&D then becomes lower in the North. As the product of R&D can be exchanged without cost, the slightest difference in R&D costs between the two regions entails total concentration of this sector in a single region, the North. The fall in the cost of innovation then leads to expansion of this sector, i.e. it acts on growth: growth therefore varies with agglomeration.

Conversely, a higher rate of growth implies greater demand for differentiated goods and therefore concentration of their production in the North: agglomeration varies with growth, which again reduces the cost of R&D and maintains the cumulative process until the R&D profit is zero, which corresponds to stable equilibrium.

This pattern is not identical in all respects to what happens in economic geography:

production is not concentrated entirely in one region, unlike R&D, which is consistent with observation. This is because of the tension between centripetal and centrifugal forces.

Centripetal forces depend on the vertical linkages we have just described between production and innovation. The centrifugal force which explains why there is not total agglomeration in one of the locations is localized demand of non mobile consumers.

Generally, integration of spatial and growth dynamics leads not only to a change in results but it also leads to greater variety in geographical configurations of growth.

Configurations that are intermediate between the pure core-periphery model and the equal distribution model arise.

Lessons and limits

Spatial concentration acts as a growth factor in its own right through the production of proximity economies. This result leads first to the following conclusion: a nation with one large agglomeration that concentrates all its growth activities may report higher growth than a nation with two medium-sized agglomerations that share those activities between them. In this perspective, everything that promotes concentration improves the potential for growth.

This is true of a reduction in transportation costs that promotes trade. It is true of public policies that aim to facilitate mobility of activities or individuals. Under these circumstances, regional integration policies lead to increased concentration of economic activities and are beneficial to growth. Everything that improves market size effects also has a favorable impact on growth. It is understandable then why the renewal of consumer goods through innovation means the spending of households can be directed towards new goods and is thus a means of sustaining growth. This is one way of understanding periods of industrialization and tertiarization of economies.

Thus growth and agglomeration processes are mutually reinforcing. There is nothing surprising in this as such, but it raises questions about the theoretical risk of explosive growth phenomena (integrating, for example, the mobility of the labor factor) while such risks are often already present in endogenous growth theories [START_REF] Amable | Les theories de la croissance endogene[END_REF].

In this perspective, everything that limits agglomeration potential (centrifugal forces) is a brake on growth. Here, the new urban microeconomic theories provide extra factors through the role of « agglomeration operating costs ». The inclusion of the land costs into regional growth models is a move in this direction.

More generally, the integration of growth theories and spatial theories must provide insight into the dynamics of agglomeration economies which appear as a combination of effects of different dynamics of accumulation of factors and of activities within agglomerations. It follows that a spatial accumulation path is drawn through the growth mechanisms and that it simultaneously defines a growth path.

The synthesis by Martin and Ottaviano with the models of Romer and Krugman meets this objective in the most natural way. Growth is evaluated by an increase in the number of firms and agglomeration results from an accumulation of the number of firms.

It may be asked though whether other forms of synthesis could not be contemplated from other forms of accumulation (human capital, public spending) and on the basis of more complete spatial structures integrating a greater variety of centrifugal forces (land market, congestion). 2 1 0 0 0 DIJON -Tel 0 3 8 0 3 9 5 4 3 0 -FAX 0 3 8 0 3 9 5 4 4 H.P. [START_REF] Minsky | Central banking and money market changes[END_REF]Minsky ( , 1975[START_REF] Minsky | Stabilizing an Unstable Economy[END_REF]. chez Minsky, l'élaboration d'une approche des fluctuations économiques tout à fait originale aussi bien au sein des théories contemporaines des cycles d'affaires qu'au sein même de la macroéconomie keynésienne. Cette approche, souvent qualifiée " d'hypothèse d'instabilité financière " s'articule autour d'une dynamique des relations de financement dans laquelle les comportements maximisateurs et innovateurs adoptés "rationnellement" par les différents agents économiques (prêteurs et emprunteurs) sont susceptibles de conduire de manière endogène non seulement à une modification de l'offre de financement (en termes de prix et de quantités) mais également à l'instabilité financière, à la récession, voire à la dépression économique.

Pour permettre la mise en place de ce nouveau service, vous trouverez au bas des pages II et 12 de la Lettre du LATEC, quelques précisions supplémentaires et un mini questionnaire.

Jacky Perreur Directeur du LATEC

CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE

PÔLE D'ÉCONOMIE ET D E GESTION 2, BOULEVARD GABRIEL -F -
L'hypothèse d'instabilité financière repose ainsi sur une vision générale du mécanisme de fonctionnement d'une économie de marché "financièrement sophistiquée". Cette vision est fondée sur une conception "endogène" et "financière" des fluctuations économiques qui s'oppose trait pour trait à la vision d'une économie harmonieuse, auto-régulée et constamment équilibrée caractérisant la Nouvelle Economie Classique 4 .

En second lieu, l'oeuvre de Minsky recèle de plusieurs développements sur les théories des cycles, riches de potentialités qui incitent à explorer diverses voies de recherches.

L'une d'elles consiste à s'interroger sur la capacité de l'approche minskyenne à renouveler et à compléter l'analyse des cycles financiers développée par la Nouvelle Economie Keynésienne 5 . En effet, cette école identifie, à l'instar de Minsky, les modifications affectant la structure financière comme des facteurs fondamentaux d'instabilité de l'activité. En outre, dans la Nouvelle Economie Keynésienne, les déséquilibres, sous forme de rationnements sur les marchés financiers, sont expliqués, comme chez Minsky, de manière endogène par les seuls comportements des agents. Ceux-ci prennent place dans une économie où l'information est asymétriquement distribuée et où prévalent les problèmes de sélection adverse et d'aléa moral. Ainsi, comme dans l'approche minskyenne, l'origine des déséquilibres renvoie-t-elle au fonctionnement "naturel" des économies de marché et non aux "rigidités" de la Synthèse IS-LM ou aux chocs, réels ou monétaires, de la Nouvelle Economie Classique.

Or, il est possible de montrer6 que les travaux de Minsky dépassent, en les enveloppant, les développements modernes nouveaux keynésiens relatifs à l'instabilité financière. Son analyse spécifique du lien entre comportements bancaires et fluctuations économiques est significative de cet état de fait. En effet, même si, dans l'approche de Minsky, l'information asymétrique exerce une influence sur les comportements bancaires, ce type " d'imperfection " ne peut être considéré comme une condition nécessaire à l'obtention d'un rationnement ou, plus généralement, d'une contrainte sur le marché du crédit. La raison essentielle en est que l'auteur analyse les relations de financement au sein d'un environnement décisionnel où coexistent information asymétrique et incertitude radicale. La prise en compte de cette dernière, qui ne s'assimile en aucun cas 4 Cette analyse est développée plus précisément dans E. Nasica M 997 et 1998).

D'autres voies de recherche, non exposées ici, sont explorées : elles essayent de modéliser l'approche de Minsky en recourant aux outils fournis par l'analyse mathématiques des systèmes dynamiques non linéaires et la théorie du chaos. Une analyse de ces modèles mettant en exergue leur apport et leurs limites est effectuée dans E. [START_REF] Nasica | Finance, Investment and Economie Fluctuations : an Analysis in the tradition of[END_REF].

Carnet de Route

O Les J7emes Journées de L'Association d'Economie Socia Je

Participation du LATEC

• Responsabilité scientifique

Maryse Gadreau En conférence introductive, Serge Christophe Kolm fit un brillant exposé sur « La théorie moderne de la justice », ciblé entre autre sur le problème de la justice distributive (« macro-justice » par opposition aux questions locales de « micro-justice»). Près de 130 chercheurs, enseignants-chercheurs ou professionnels des institutions sociales locales ou nationales ont participé aux 4 séances plénières et aux 10 ateliers de ces journées aux cours desquelles une cinquantaine de communications ont été proposées. Présentations et débats ont fait apparaître l'intérêt d'un détour théorique, voire même épistémologique, sur les fondements et les modalités des politiques sociales, que ce soit dans le champ de la formation et de l'emploi, de l'éducation, de la santé et de la protection sociale ou encore de la culture.

La première conférence plénière, suivant immédiatement la conférence introductive de S.C. Kolm, a ciblé précisément la question de « L'équité dans les politiques sociales » tant au niveau théorique qu'aux niveaux de la politique de santé et de la politique familiale.

La seconde conférence « La formation des politiques sociales » était relative à la formation des politiques sociales en général et plus particulièrement dans les champs de l'éducation et de l'art contemporain. Les communications ont permis d'examiner quels rôles pouvaient jouer les contrats et les conventions dans l'émergence, l'efficacité et la stabilité de ces politiques.

La troisième conférence plénière « Emploi et insertion : mise en perspectives » ciblait un domaine : celui de l'emploi et de l'insertion. A travers les communications présentées, il s'agissait d'apprécier les apports de certains développements contemporains (sur les phénomènes d'appartements, sur les conventions ...) ou plus anciens mais revisités (l'approche commonsienne ...) pour mieux comprendre et mieux prévoir le fonctionnement du marché du travail et de l'insertion.

Enfin la dernière conférence rassemblait deux communications originales : l'une sur la recherche d'un « Premier fondement théorique d'une non division du travail dans les ménages », l'autre sur « La pré-coordination des agents et les droits de propriétés :

• Publications

Actes du Colloque : 2 volumes Contactez : M.T. Rapiau IREDU-CNRS, 9 Av. A. Savary BP 400 -21011 Dijon Cedex (Prix : 300 F)

• Distinction

Prix de thèse Jacques Tymen Claude Schneider-Bunner

• Nomination

Maryse Gadreau, Présidente l'A.E.S pour l'année 97-98. Au terme de ces journées -dont la dimension festive n'a pas été négligée -certains thèmes, certaines interrogations apparaissent cruciaux pour l'économie sociale comme pour l'analyse économique. Ainsi, l'intérêt porté aux théories de la justice peut être perçu comme un retour aux sources de l'économie où la philosophie morale et politique était étroitement associée à l'analyse économique, mais aussi comme une refondation théorique de la régulation économique et sociale qui débouche sur des implications majeures en politique sociale : quelle légitimité et quelles modalités pour le RMI, les prestations familiales, les aides à l'emploi ... ?

Par ailleurs, les politiques sociales (de l'emploi, de la santé, de l'éducation, de la culture ...) sont interprétées à partir de concepts nouveaux tels que le contrat ou la convention, riches d'enseignements, mais dont l'ambiguïté est loin d'être entièrement levée quant aux pouvoirs descriptif et prédictif des analyses qu'ils initient.

D'une manière générale, l'économie sociale, de par sa dimension transdisciplinaire, constitue un terrain porteur pour la confrontation de paradigmes différents et l'expérimentation de politiques nouvelles.

A l'occasion de cette manifestation annuelle, l'Association d'Economie Sociale a décerné le prix Jacques Tymen. Le prix de thèse a été décerné ex-aequo à Claude Schneider-Bunner pour sa thèse intitulée Economie et justice sociale : l'organisation et la régulation des systèmes de santé face à l'équité (sous la direction de Maryse Gadreau, Université de Bourgogne) et à Rachel Biville pour sa thèse intitulée Analyse économique des associations sans but lucratif {sous la direction de Edith Archambault, Université de Paris I). Le prix de mémoire a été décerné à Yannick Fondeur pour son travail intitulé Insertion professionnelle des jeunes, cycle économique et diplôme (sous la direction de Michel Vernières, DEA Economie des Ressources Humaines et des Politiques Sociales de l'Université de Paris I).

Les prochaines journées de l'Association d'Economie Sociale se tiendront à Marseille, en septembre 1998 sous la présidence de Maryse Gadreau. Organisées conjointement par le CEREQ et le LEST, elles traiteront de la construction des politiques sociales catégorielles aux niveaux national et international. Sous l'intitulé suivant, encore provisoire, « Pertinence et impertinence des catégorisations en économie sociale », il s'agira de présenter et de discuter les fondements et les modalités de la notion de « politique sociale catégorielle » à partir entre autres des expériences angloaméricaines de discrimination positive. Le débat universalisme versus communautarisme sera sous-jacent à ces journées.

Maryse Gadreau GRES-LATEC

O Co/Joques

  le LATEC possède son site Web. Mis en place et géré par Alain Fauvre, ce site vous fournit les principales informations concernant le LATEC : sa localisation sur le Campus, ses chercheurs et enseignants-chercheurs ainsi que les différents thèmes de recherches développés. A partir de janvier 1998, vous pourrez également consulter directement les Documents de Travail produits par les chercheurs. Ce nouveau mode de diffusion remplacera, à terme, la diffusion des Documents de Travail sur support papier, celle-ci devenant exceptionnelle. Tous nos correspondants, et ceux qui en feront la demande, recevront semestriellement un document écrit comportant les résumés des Documents de Travail sortis au cours du semestre. Ce site ne demande qu'à être enrichi et nous pourrons l'alimenter selon les demandes de chacun d'entre vous.

  idées centrales peuvent caractériser les modèles développés par cette école. La première a trait au rôle secondaire conféré aux facteurs financiers dans l'explication des fluctuations économiques. La deuxième renvoie à la conception "exogène" de l'instabilité économique développée par les économistes de ce courant. En effet, dans le cadre théorique utilisé par la Nouvelle Economie Classique, les mécanismes concurrentiels du marché sont assez puissants pour conduire l'économie, en l'absence de toute perturbation externe, sur une position d'équilibre dans laquelle tous les plans des agents individuels sont mutuellement compatibles. Toute forme d'instabilité observable doit donc être attribuée à des chocs (monétaires pour la théorie des cycles d'équilibre ou technologiques pour la théorie des cycles réels) exclusivement exogènes qui viennent troubler l'équilibre naturel du système. Diverses raisons conduisent néanmoins à s'interroger sur la pertinence de l'explication des fluctuations économiques proposée par les nouveaux économistes classiques et, plus généralement, sur la validité d'une approche négligeant totalement le rôle des structures financières dans l'apparition et le développement des cycles d'affaires. La première raison est d'ordre empirique. En effet, le nouveau ralentissement de la croissance que les pays de l'OCDE ont tour à tour subi au début des années quatre-vingt-dix apparaît, dans une large mesure, relié à l'évolution de leurs structures financières au cours de la décennie quatre-vingt. Durant cette période, l'accumulation de dettes a entraîné une fragilité financière qui est restée dissimulée aussi longtemps que des plus-values sur actifs ont été dégagées. Cette situation a néanmoins rendu les emprunteurs plus vulnérables à un choc imprévu. En particulier, la hausse brutale des taux d'intérêt à la fin des années quatre-vingt, qui s'est produite sur un terreau de fragilité financière, a eu des incidences bien plus spectaculaires (effondrement des prix des actifs, hausse des défauts de remboursement...) que si elle avait agi, à amplitude égale, sur des agents aux structures financières robustes. Dans ce contexte, les efforts des entreprises pour élever le taux d'autofinancement bien au-dessus de cent pour cent, dans le but de se désendetter, ont entraîné une baisse prononcée et durable des investissements productifs. Le rôle central de ces ajustements financiers apparaît ainsi comme l'une des caractéristiques essentielles du ralentissement de l'activité économique du début des années quatre-vingt dix. Au-delà de ces considérations empiriques, l'idée de s'intéresser au rôle des structures financières dans l'analyse des fluctuations économiques est également liée au traitement insatisfaisant des relations de financement au sein de la théorie des cycles réels. Certes, les frontières de ce courant tendent à devenir de plus en plus floues. En particulier, l'une des tentatives de dépassement a consisté à introduire une dimension nominale et à retrouver le rôle de la monnaie dans les fluctuations de l'activité 1 . Cependant, les différentes voies empruntées pour "remonétiser" les modèles de cycles réels sont, dans l'état actuel des choses, loin d'être convaincantes 2 . Il apparaît dés lors nécessaire de s'interroger sur la possibilité de réintégrer les facteurs financiers dans l'analyse des fluctuations économiques et sur les modalités associées à une telle réintégration. Dans cette perspective, la voie de recherche ouverte par Hyman P. Minsky dès la fin des années cinquante 3 mérite une attention toute particulière. L'approche de cet économiste récemment disparu, souvent assimilé aux économistes Post-Keynésiens, mais en réalité difficilement classable dans tel ou tel courant de pensée, apparaît en effet porteuse de plusieurs enseignements importants. En premier lieu, la démarche de Minsky permet de remédier à certaines limites importantes de la théorie Post-Keynésienne traditionnelle regroupée autour des travaux de Davidson (1994) et de Kregel (1973). D'une part, ces auteurs n'utilisent pas les fondements théoriques sous-jacents à leur critique de la Nouvelle Economie Classique pour bâtir une analyse des cycles alternative à celle développée par cette école. D'autre part, leur théorie prend insuffisamment en compte les liens entre structure financière et instabilité économique dont nous avons rappelé ci-dessus l'acuité et l'actualité. En revanche, si on retrouve dans l'analyse de Minsky les thèmes principaux du "fondamentalisme" keynésien (rôle de l'incertitude et des comportements qu'elle engendre, instabilité dynamique des économies de marché, rôle de la monnaie et incidence des comportements de préférence pour la liquidité), ses travaux sont également fortement influencés par dle cas en particulier des contributions de R. King et G. Plosser (1984), S. Williamson (1987) et T. Cooley et G. Hansen (1989). Pour une analyse plus approfondie de la question, on pourra se référer à l'article de P. Y. Hénin ( 1989). 5 Cf. G. Stadler(1994).

  3

de

  Nozick et Rawls et la fraternité ».

  de thèse ce-financée par le Conseil Régional de Bourgogne et l'Agence Régionale de l'Hospitalisation de Bourgogne sur le thème « L'arbitrage qualité-équité dans la production d'un bien public. L'exemple des doctorante (Directeur de thèse : Maryse Gadreau) a été recrutée en tant qu'Ingénieur à la Mission PMSI au Ministère de l'Emploi et de la Solidarité à Paris. Elle a été chargée du dossier « Echelle commune » pour lequel il s'agit d'élaborer et de mettre en place une échelle commune des coûts de l'activité « court séjour » (Médecine -Chirurgie -Obstérique) entre le secteur public et le secteur privé. Thèses Estelle Orivel, Légitimité de l'intervention de l'Etat dans le domaine des arts. Rationalité des acteurs et optimum social, directeur Bernard Rouget, mention très honorable à l'unanimité avec les félicitations du jury et propositions pour prix de thèse et subvention, Dijon, 30 septembre 1997. Fabienne Midy, Qualité de vie et évaluation économique. Des fondements théoriques à la mise en pratique, directeur Sophie Béjean, mention très honorable à l'unanimité avec les félicitations du jury et proposition pour prix de thèse, Dijon, 30 octobre 1997 Le LATEC sur INTERNET I \ Afin de mettre en place ces nouveaux services, pourriez-vous remplir le questionnaire A partir de janvier 1998, les nouveaux \ ci _ Qprès et { > adressert ^mt !e 15Janvier l998t a . Documents de Travail du LATECi Catherine Baumont, LATEC, Pôle dEconomie et de Gestion, 2, bd Gabriel, pourront être consultés sur le site Web \ p. 2 J000Dijon -n° Fax : 03 80 39 54 43 du LATEC. La diffusion sur support. e mail : Catherine.baumont%u-bourgogne.fr papier «aux particuliers» sera à terme j supprimée et ne sera exceptionnelle-1 ment ou provisoirement conservée quej Nom..rTenom pour «les échanges inter-laboratoires» i Fonctions : et «les particuliers» qui ne peuvent j Coordonnées professionnelles (ou personnelles) : adresse, Tel, Fax, e-mail... avoir accès à Internet. i Un « 4 pages » semestriel comportant j les résumés, en français et en anglais, i des Documents de Travail parus au j cours du semestre sera envoyé à ceux i U £/£ ro ï à être ! 17 Aurez-vous la possibilité de consulter le site Web du LATEC ? diffusée sur support papier.

  In both models, the centripetal forces arise from the vertical linkage between industrial goods and intermediate goods, either because the intermediate goods are immobile or because they are expensive to transport. This is compounded, in one of the cases envisaged by Englmann and Walz by the strictly local (internal to one region) character of the growth externality: it is the local number of intermediate goods produced that makes the development of new varieties by R&D less expensive. Exogenous centrifugal forces are generated by the existence of non-mobile factors: for Englmann and Walz, this is unskilled labor and above all intermediate goods; for Walz, it is land or unskilled labor or local infrastructures. This is compounded by an endogenous competition effect that tends to separate the new firms producing intermediate goods from

	The production structure
	is based on four sectors corresponding to a traditional good, a manufactured good, a
	differentiated intermediate good and R&D, respectively. The manufacturing sector uses
	differentiated intermediate goods with increasing returns: the increase in the number of
	varieties of intermediate goods increases productivity. Intermediate goods are produced with
	skilled labor and knowledge produced by R&D. R&D invents new varieties of intermediate
	goods with mobile labor and benefits from Romer-type spillovers: knowledge produced by
	this sector increases its own productivity so that the cost of the creation of new varieties of
	intermediate goods decreases with the total number of varieties that already exist.

In the Englmann and Walz model, intermediate goods are immobile. In that of Walz, they are not fully mobile, as they are subject to transportation costs.

• Présidence de sessions

		COMPTE-RENDU
		Les 17èmes Journées de l'A.E.S. ont été organisées conjointement
		par le LATEC (Responsable scientifique : Maryse Gadreau) et par
		l'EREDU (Responsable scientifique : Jean-Claude Eicher), à Dijon,
		les 11 et 12 septembre 1997 sur : «
	° Maryse Gadreau	Conférence
	plénière II « La	formation des
	politiques sociales	contrats ou
	conventions »
	° Jérôme Lallement	Conférence
	plénière III « Emploi et insertion :
	mises en perspectives »
	• Communications
	Séances plénières
	° Claude Schneider-Bunner et Fabienne
	Midy, « L aide à la décision en santé.
	Vers une approche pluraliste pour
	concilier efficacité et équité »
	0 Estelle Orivel, « Convention de
	qualité et caractère méritoire de l'art
	contemporain : le rôle de l'Etat »
	Ateliers
	0 Sophie Béjean et Christine Peyron,
	« Contrats et conventions : quels ap-
	ports pour l'économie de la santé? »
	0 Daniel Goujon et Thierry Fournier,
	« Efficacité de la politique du Revenu
	Minimum d'Insertion : un problème de
	définition et d'exclusion »
	0 C. Mathy, « Qualité et assurance-
	qualité à l'hôpital : quels fondements
	et paradigmes économiques ? » (en
	collaboration avec E.-A. Sauleau)
	0 Louis de Mesnard, « Des problèmes
	posés par les indices de mesure de
	l'inégalité »

Les avancées théoriques en économie sociale et leurs applications ».

Cf. E.[START_REF] Nasica | Comportements bancaires et fluctuations économiques : l'apport fondamental dTIyman P. Minsky à la théorie des cycles endogènes et financiers[END_REF][START_REF] Nasica | Finance, Investment and Economie Fluctuations : an Analysis in the tradition of[END_REF].au risque probabiliste retenu par les nouveaux keynésiens, conduit les banques, indépendamment de toute référence à l'aspect "symétrique" ou non de l'information, à adopter un éventail de comportements qui va bien au-delà de la simple émergence d'un rationnement quantitatif sur le marché du crédit. En effet, dans cet environnement d'incertitude véritable, l'adoption de comportements fondés sur une forme particulière de rationalité dans laquelle les conventions et, éventuellement, les "esprits animaux" ont une place centrale, implique que les banques n'agissent pas conformément à l'agent représentatif de la théorie des anticipations rationnelles. D'autres comportement et d'autres variables, sont ainsi ramenées au premier plan : le niveau d'endettement de la structure financière des banques, les ratios d'endettement jugés acceptables, les variations de " l'état de la confiance" et de la préférence pour la liquidité des