Eric Verdeil
email: eric.verdeil@normalesup.org

The Reconstruction Between Urban Planning Policies and Cultures: Beirut-Based Reflections

89. It was first presented during the conference Waad: The uniqueness of experience. Workshop on the reconstruction of the Southern suburb of Beirut after the Israeli aggression in 2006, 12-13 June 2012.

Introduction

Post-war reconstructions are controversial and politically charged. The political dimension is at the same time a constraint and what guides expectations of change. However, technical and urban dimensions should not be underestimated during any project evaluation. Thus, assessing a project similar to Waad involves finding an acceptable way to join together the two dimensions.

A second remark preceding this analysis notes that, in general, the assessment of a planning operation is not only related to the context and to the present. It rarely disregards similar interventions in different areas or even in the same area but in previous times. This is proved by the debates that acted as a trigger in starting and executing Solidere, Beirut Downtown reconstruction project starting 1991. Moreover, the mobilization of opponents heavily relied on plans and principles of Chehabism urban planning as well as on the 1977 reconstruction plan, seen as a model project 1 . However, comparisons are sometimes misleading, and criteria upon which a solid analysis is built should be justified. Beyond the normative and political dimension, comparing reconstructions poses methodological problems: it is necessary to take into account the differences of the political context, including the nature of the conflict and power relations between actors, the urban context (localization, destructions nature, local issues) and the urban context, marked by the urban conceptions development.

The two remarks contribute to defining the adopted approach. This paper aims at proposing and testing a conceptual framework that allows for understanding the constraints, the political wills, the 1 Refer to, for example: Beyhum Nabil, 1992, « The Crisis of Urban Culture ; The Three Reconstruction Plans for Beirut", The Beirut Review, n°4, pp.43-62; Tabet J., 1991, La ville imparfaite, in Beyhum N. (éd.), Reconstruire Beyrouth. Les paris sur le possible, Lyon, Maison de l' Orient, p. 85-120. temporalities and the different urban contexts where reconstructions are taking place. This framework focuses on two dimensions. The first dimension is related to reconstruction policies, as an expression of permanent transformations of the social relations caused by war and destructions (for example, migration, and enrichment/depletion of different groups…). The reconstruction policies involve understanding the urban space as a place where political power relations materialize, on the international, national or local level. The second dimension in this framework is related to the planning cultures. Bish Sanyal defines the planning cultures as "the collective ethos and dominant attitudes of planners regarding the appropriate role of the state, market forces and civil society in urban, regional and national development" 2 . According to my previous work, it is necessary to complete this definition by incorporating to this analysis professional factors related to the planning field (for example, the factors that define controlling various professions) and the localized variations of these cultures nationally 3 . I will apply this framework in order to highlight the main similarities and differences between four periods and experiences of reconstruction in Beirut Downtown as well as in the Haret Hreik neighborhood concerned by the Project Waad.

First axis: Reconstruction policies

In order to define the reconstruction policies, six criteria are put forward.

Project reference population

Initially, the reference population of the project, i.e the population affected by the project, must be defined. This category includes the inhabitants and the assets or enterprises installed in the area. It also includes other categories of users who might use to the rebuilt sector. Consequently, in order to define the reference population, the scope of the project, as well as the centrality of the sector rebuilt in the urban area, should be defined. Subsequently, different cases could be identified. Some sectors are characterized by a metropolitan centrality. Their reconstruction doesn't only concern the site inhabitants' and workers' but it also concerns the urban area population and even the whole country population. In this case, defining the aims of infrastructures, public services and spaces is crucial. Indeed, the diversity of the target population could lead to conflicts, for example between the local population and a population of tourists or expatriates, or even investors and international companies, as they don't expect the same services as the local population. The de facto exclusion of the frail categories, through construction regulations and subsequently through the market, is extremely risky for similar projects.

In other cases, the centrality of the sector is mostly experienced at the municipal level is encountered. The population is defined by its registration in the locality and its needs and practices 2 Sanyal Bish (éd.), 2005, Comparative planning cultures, New York, Routledge, p.3. 3 Souami Taoufik, Verdeil Eric, 2006, Concevoir et gérer les villes : milieux d'urbanistes du sud de la Méditerranée, Paris-Beyrouth, Economica/Anthropos -IFPO, 229 p. et Verdeil Éric, 2012, « Michel Ecochard in Lebanon and Syria (1956-1968). The spread of Modernism, the Building of the Independent States and the Rise of Local professionals of planning", Planning Perspectives, avril 2012, vol. 27, n°2, p. 243-260 should also be defined. Even in similar situations, the definition of the reference population might cause some problems and trigger latent conflicts. Consequently, the pre-mentioned dilemma can also be encountered.

On a larger scale, the definition of the reference population pertains to the following question: given the ability of urban planning to transform the social space, to which extent can urban planning be considered as a territorial demarcation tool of social or confessional groups, excluding, de facto, some population categories from the rebuilt spaces?

The Reference Ideology

Urban planning involves the interaction between symbols and construction of identities.

Besides functional orientations of town planning programs, speeches of justification, overall aesthetic, distinct buildings or major public spaces are revealing. Thus, two parameters should be taken into consideration while assessing reconstruction projects:

 The relation with the national construction. Does the project promote national unity, intermixing of social, ethnic or confessional groups which constitute the population of the country or on the contrary, does it reveal (sometimes implicitly) a message of division and segmentation, through the planning and meanings it carries?

 The relation with the world. Urban planning is a form of economic and symbolic articulation worldwide. Architectural and urban forms, as well as the practices it could lead to, are important key players. The choice of urban and architectural forms, vernacular or internationalized, is a good indicator. However, programs results could also be eloquent: luxury hotels and commercial centers, financial city or other facilities could reveal a willingness to join such a capitalist globalization.

Reconstruction Temporality

The temporal dimension of the reconstructions should be perceived with respect to three specific temporalities. Temporality is related to time and it is assumed that subjects or actions are differentiated from each other by the means of temporal characteristics4 . Thus, the following should be noted:

 Project Duration: it may be short, involving minimal changes to the urban and architectural structure, or may be longer, as a result of larger works and a more ambitious plan. Urban modernization projects, which result in major modifications to the architectural and urban structure, clearly illustrate the situation. It should be noted that, in general, a long urban history (many projects and many failures of previous interventions) leads to more ambitious projects or at least more complex. Therefore, their execution requires a longer period of time.

 The duration of destructions and urban mutations is the second element that should be noted as it contributes to the reconstruction project design. Sudden destructions, mainly affecting the physical organization of the city, don't have the same effect as destructions of long duration that imply, in addition to the physical destruction of the buildings and infrastructures, a deep transformation of the society social structure (for example, permanent migrations, depletion or enrichment of certain groups, irreversible functional mutations). All the elements make the return to the normal or to the "analogue" impossible and even utopian. The memory of the place becomes senseless.

 The past of the projects for a defined site is the third major dimension. The projects and previous attempts being numerous, an urban planning memory of the place is constituted. It is sustained by the willingness to transformations, failures, reformulations, in addition to the intentions of professionals and political and economic actors, the key players. It is opposed to the ordinary memories of the place, based on the practices and representations of the urbanites. Urban planning memory is available and is mobilized by political and urban actors. It includes interventions much more complex and sustained by the willingness to transformation which sees reconstruction as an opportunity that should be seized. Conversely, if previous projects are rare or absent, it means that few credible and asserted alternatives are available. Thus, the adopted projects tend to be more conservative.

The foreseen urban fabric

The characteristics of the future rebuilt urban sector are major to reconstruction, which is, in general, subject to intense debates. These debates are often built on the axis of conservationremodeling, conceived according to the three-level typo-morphology analysis: the architecture, the plot canvas and the road network.

Reconstruction, as a radical and pure modernization, is generally linked to a profound power relations renewal and thus implies a major alteration in the social fabric. In contrast, heritage planning is meant as a supports for (re)constructing identity. However, the model of Warsaw proves that "faithful" reconstruction always relies on the selection of the a past state as a reference. In Warsaw, the reconstruction of the plot canvas and the architecture of the XVII and XVIII centuries required denying the Polish capital social development. It also reflected a nationalist exaltation of its architectural and urban golden age. The return to the analogue always involves complex reconstructions of the past, related to ideological debates and political power relations, which are not less meaningful as in the case of modernizing reconstructions.

Legal tools

As any urban planning project, reconstruction requires setting the legal tools to acquire the project land management and ensure a coordinated management. The different legal tools involve different action and operation models.

On the land management level, two factors are crucial. The first is the scale of the operations: the parcel, a limited land pooling or a total land pooling related to the reconstruction zone. The second is related to the partnership of the eligible stakeholders in the development structures. Expropriation excludes the eligible party, while land pooling preserves its rights, including the localization, and the real estate company (as existing in Lebanon) makes in principle the eligible stakeholder a shareholder. Thus, the relation of the owner or eligible stakeholders with the place could be preserved, dissolved or abolished.

On the urban management level, the issue of works coordination is raised: temporal phasing, global and cross-region interventions (highways, varied networks) and definite unity (public spaces remodeling). A centralized approach, by a planning body, could be ensured through a mixed real estate company or a mixed economic company, as is the case in France. But an excessive centralization could result in financial risks, poor and unimaginative homogeneity, while a more decentralized management gives some leeway and flexibility, as explained by Joe Nasr in comparing the approaches of Berlin to Beirut in the 1990s5 .

A third legal factor depends on the reconstruction duration. However, legal validation of the future project, through an approved plan according to democratic procedures, allows some revisions depending on economic conjuncture or political priorities evolution. Revisions must be allowed but must not be subject to the sole discretion of the developers.

Project Funding

Project funding doesn't mainly relate to discussions concerning financial or economic techniques. It rather relates to political choices between two different poles: the market and the national or international financial solidarity.

Financing the project through the market involves seeking a balance, or even a profit between the development expenditures and revenues. Lands and properties have to be adapted according to customers' and investors' needs. Financing through the market results in either a strong social selection, usually at the expense of the poorest, or in the concentration of the poorest in socially undeveloped areas.

National funding through taxes, subsidies (loans and grants for example) and other solidarity forms (contribution) doesn't compensate for economic austerity but helps defining other objectives as profitability. It also helps adapting to an economic imbalance of the operation, for example in order to keep the population in the area or to preserve an unprofitable architectural heritage (two options that are slightly compatible)

Second axis: Planning Cultures

The second axis of the conceptual framework is based on three criteria: Urban planners' profiles, the logic of professional institutions, and professional experiences and mobilizations. Their definition will be concise, shorter than in the previous section, and will somehow be theoretical. It will lead to planning cultures typology involved in the reconstructions.

Urban planners' Profiles

Following Gilles Verpraet6 analysis, two main urban planning profiles of practice could be contrasted.

The first and the most classical one, is the logic of expertise based on enjoying specific knowledge and skills. The urban planners claim monopoly in defining the projects contents, in agreement with the policy guidelines and at the risk of a technocratic drift. Conversely, the logic of mediation makes the urban planners intermediaries between various interest groups, such as the economic actors, inhabitants, etc. Their role is then to work on adjusting the different interests and reaching compromises to launch projects.

These urban planners' profiles are directly related to the national and local structuration of the profession and to how it correlates various occupations and professional specializations, such as the profession of the architect, the engineer, or the sociologist.

The Order Logic

The issue of the urban planners' profiles is narrowly linked to the professional field structure in terms of defining the order. Two major divisions traverse the field of urban planning. The first opposition distinguishes the public client from the private client. While the private demand logically relies on the market, public order in the contrary can be very diverse in its expectations. The second division opposes central and local logics and thus leads to the aggregation of the interests.

Shared experiences and professional references

This last factor is essential to apprehend urban planning cultures. It refers to the urban planners' socialization conditions and to which extent they affect the profession definition of legal challenges and major system of reference, whether ideological or professional. In this respect, the structuring professional mobilizations of the urban planners' experience must be identified. 7 .

Those experiences and professional references can be included in the broader political context. For example, in Lebanon, in the years 1960-70, the decolonization, nationalism and development represented shared values for planning professionals. In another scenario, they could represent professional mobilizations surpassing the borders. The adherence to modernism in architecture in the 1960s is a good example. Sharing concrete professional references, as the experience of the new towns in France known through education or professional practice, constitutes another possible illustration.

Generation effects are extremely strong and influential in creating shared references, on both political and professional levels. Thus, functionalism can be seen as a symbol of the professional culture of the years 1950-70, while current generations adhere to other values, such as taking into account the environment or the heritage. These dominant or shared conceptualizations in the professional environment, heavily and implicitly, affect the orientations of the projects.

Four cultures debated in Lebanon

How do the components of planning cultures act, precisely, in orienting the visions and the development projects including reconstructions? In order to understand this issue, four types of professional planning cultures existing in Lebanon are defined by the combination of these three elements (profile, control, references). Their role in the reconstructions that Beirut knew will be then examined.

State-controlled culture. In this first type, the government is seen as the legal authority able to define the general interest and also the principal leader of the studies. Urban planners are nothing but experts. The profession is structured by coalitions of professions, including public sector engineers and private sector architects. In Lebanon, as from the years 1960 and approximately until the beginning of 1990, the Chehabism, joining will of national construction and developmentalist project, constituted the major reference to the professional environment. 8

Neoliberal culture. This culture appraises the principle of the market and competition, perceiving the city as in competition with other regional metropolises to attract investments which trigger economic growth. This logic arranges the retreat of the government as an operator by incentive rules in tax terms and by promoting flexible planning projects. From this point of view, the urban planner is often the consultant of a private customer and privileges a financial approach in the definition and evaluation of the project while disregarding the urban social dimension or urban challenges (centrality, public spaces, etc.) 9 .

In the municipal culture, urban planning is defined in close liaison with the electoral game and thus taking into account the local voters' interests is compulsory. Peopling of a municipality is a major factor of political reproduction and thus satisfying the interests of the inhabitants while stabilizing the peopling (i.e. the electorate) becomes a major aiming of the municipal action. The policy of the communist suburbs municipalities in France is an example of this logic: the Communist party, a powerful and organized party, has managed to persist locally in spite of a continuous degradation of its national influence by meeting the expectations of its population in terms of housing, employment in municipal services, defense of the industrial employment, sports facilities, etc. Thus, the party has maintained a local base that allows it to have a politically influence, in particular at the National Assembly, greater than its influence on the total population 10 . understanding the political control and decoding the social needs, then interpreting them into urban projects. Municipalities in Lebanon sorely lack today for human and financial resources.

Beyond the few municipal officials, local urban planning heavily relies on the commitment of local politicians, often with expertise in development in a broad sense (civil engineers, architects, etc)11 .

Participative culture. Many controversies aroused around development projects during the post-Lebanese civil war period. Protests over the project for the downtown area of Beirut (1991-1995), conflicts over heritage or environmental matters in Lebanon (the coast, quarries), etc are noteworthy. These debates showed the interest of the citizens in urban issues and their willingness to getting organized and influence urban projects. Very often, the groups which emerged and disputed the action of the public collectivity or developers included planning professionals, often young, committed to new ideas promoting the democratic decision (as opposed to technocratic decision or dictates of politico-financial interests). Urban planners are here considered as intermediates attending to the interests of the citizens and the promotion of new values12 .

Comparative Reading of the Reconstruction Projects in Beirut

Taking into consideration the two reading axes previously presented, this section analyses the four periods of reconstruction of Beirut and its suburbs, in 1977 following the two-year war, in 1982-1983 under the presidency of Amine Gemayel, from 1991 with the start of the project which was entrusted later on to Solidere, and finally the case of Waad, following the 33-day war in 2006 13 .

1977: The First Downtown Reconstruction Project

From the reconstruction policies perspective, the project of 1977 is characterized by an ideology putting forward the idea of recreating an oriental Mediterranean city, an amalgam of different communities allowing that conviviality is restored. Not to mention that the role of the government, considered as a guarantor of the national unity, is also asserted.

The target population is mainly composed of the souks merchants, and of the citizens who used to live in those areas. The project also takes into account the interests of the business districts which favored the modernization of the down town.

Considering the project temporalities, it should be noted that even if the destruction was of great importance, the landmarks have remained. The war lasted for just two years. The traders and the stakeholders claimed a quick return to normal life: their memories were still so fresh. Nevertheless, the reconstruction conception was stamped by projects from the past, i.e modernization projects that go back to the Chehabist period and aim at reorganizing some business neighborhoods consisting of modern towers and buildings, as Ghaghloul and Saifi. Although urban planners wanted a quick project, they knew that some of those subprojects would require more time to be realized.

The urban tissue being involved, the predominant idea was the conservation of the status without a real heritage preservation. Strict protection of the existing urban fabric was not imposed but some measures that limited the heights aimed at hindering the urban fabric renewal through speculation. However, some sectors were to be strongly remodeled, as for example opening new roads and building the port slab, using various mechanisms: land consolidation, real estate companies and expropriation.

Concerning the funding, indemnities paid by the government as compensations for the damage were projected. However, the market role was seen as an essential element for the project funding. At that time, creating a state-controlled public institution and real estate companies, joining the eligible parties with the government, was highly considered.

In regard to professional cultures, the project was a direct continuation of the chehabism and thus promoted a culture of state-controlled urban planning. The government, serving the public interests, played an essential role through Amin Bizri, the Minister of Public Works, who was an architect and urban planner. The municipality was officially involved and met the demands of the merchants. In fact, a supervision comity, composed of local experienced professionals and acknowledged experts, coordinated with the French and Lebanese consultants and ensured the project elaboration with the Mohafez (Mitri Nammar) and the minister. The war broke out and prevented its execution.

1982-1986: The Second Downtown Beirut Reconstruction Attempt

It is not a new project but rather the continuation of the project suspended in 1977. The new damages had to be taken into consideration. However, after 1983, the studies that were secretly conducted by the firm OGER LIBAN had significantly altered the content and the orientations of the project and set up most of the orientations that would be adopted in 1991.

President Amine Gemayel believed in the ideology of economic liberalism relying on the Lebanese merchant culture, supposedly of Phoenicians origins. The reconstruction project highlighted the presidential project of Amine Gemayel, which depended on entrepreneurs like Joseph Khoury and Rafiq Hariri.

Compared to the 1977 project, the project acknowledged the exile of multiple businesses and companies, relocated at Mar Elias, Sassine, Bourj Hammoud or Jdeideh. The new projects that were elaborated during the 1980's were defined for new customers: rich citizens, Lebanese expatriates or Arabs from the Gulf.

The project was also marked by the alarming destructions, with the demolition (unanticipated) of a part of the Souks by OGER LIBAN for security reasons. In addition, the Normandy dump caused a great alteration to the site. All the transformations justified the elaboration of modernization and densification projects which relied on old projects but developed them. Thus, a quick return to the normal and to the analogue was impossible. On the contrary, great transformations were made.

Regarding the operational tools and funding, the level of damage required for the intervention necessitated looking for integrated solutions. Starting 1986, the first outlines of a global real estate company were proposed by Oger Liban. Moreover, the projects were more and more oriented, within a perspective of financing through the market and towards the promotion of luxury real estates.

The project clearly foreshadowed the emergence of the neoliberal culture, marked by the political and economic emergence of Rafic Hariri and by the preponderance of private consultants as the group OGER whereas public administrations were marginalized. These studies were executed behind closed doors and provoked little debates after 1983, as the press was highly interested in the controversy aroused by the archaeological heritage conservation.

1991: Downtown Reconstruction by Solidere

Downtown Beirut Reconstruction by the real estate company, Solidere, is considered as a turning point and a key reference in the Lebanese urban planning (and even international). The region has never witnessed such a huge building site. If the transformation of the Gulf cities was spectacular and became a new reference, the operation held by Solidere was really particular. Whatever the opinion regarding this project might be, the importance and quality of the achievements, the steadfast intentions and the efficient works done could not be denied.

This project represents the neoliberal urban planning, marked by an inter-cities competition, in which Beirut aimed at regaining its prosperity in the face of the other Arab cities and cities of the Gulf. One of the major goals of the project was to attract Arab investments, considered as the drivers of the national development, to Lebanon.

The majority of the target population, Lebanese expatriates or wealthy Arabs, did not live in the country. The return of the eligible stakeholders, the old citizens and merchants, was clearly not studied. As for the refugees who occupied the place, their relocation was quickly arranged. The project proposed national unity, reconciliation and communities' coexistence through the restoration of religious sites. However, some confessions don't have any religious sites in downtown, particularly the Chiaas. Moreover, the coexistence of religions has become a "face-to-face", as proved by the concurrence of the minarets and steeples, specifically during the reconstruction of the new mosque next to the mausoleum of Rafiq Hariri, and the restoration of the maronite cathedral and its new steeple. As a result, on the social and the religious levels, urban planning seemed to be an instrument of segmentation and not of unity. The temporalities of reconstruction were particular. At first, the memory of the previous society was demolished, not only because of the destructions caused by the war or by the fact that the citizens made their life in other areas or abroad and the merchants got installed in other areas, but also because of a tabula rasa which strengthened those broken ties with the past. The project set up the development of a modernizing logic which has already been taking root but was expanded and applied to the whole project. As for the reconstruction duration, it was perceived as too long. At first, it was set to 25 years, but was extended to 75 years.

The rebuilt urban tissue is characterized by a largely reconstructed urban system, including the addition of embankment of over 60 ha and a frame highly densified by the elimination of 80% of the buildings that existed during the pre-war period, except for some sectors as Etoile-Foch or Saifi. Despite the violent modernizing project, Solidere knew how to build numerous and quality public areas, although they were being policed and were under high surveillance and the practices considered as deviant were banned.

Finally, concerning the operational management and funding, a private real estate company took over. It managed to expropriate all the eligible parties and practiced real estate speculation ensuring project great returns. On the planning level, Solidere took advantage of multiple revisions made to its urban planning regulations thanks to the Council of Ministers, which ensured that the project met the needs of the company, sometimes at the expense of some eligible parties or other parties, as it is the case of Saint George beach.

Concerning the planning cultures, Solidere is emblematic of neoliberal urban planning emergence, marked by the market supremacy, internally managed by urban planners, employees of the company, and supported by various consultants. Nevertheless, continuaties with past projects should be emphasized. For instance, the participation of urban planners as Henri Edde or Dar al Handasah group to the project set up is a clear continuation of their participation in the previous stages. In addition to that, Solidere has benefited from the government administrations great support (especially the CDR), showing a permanent state-controlled planning culture in Lebanon and legimitizing a centralized approach to the urban issues in opposition to a decentralized approach, one that would have offered the municipality a higher involvement in the decision making, without mentioning a more participative approach. However, the project acted as a catalyst for the urban debate in Lebanon, as other perspectives of urban planning could be raised and attracted part of the public and professionals. Finally, if Solidere clearly did not stand for a participative approach, it provoked some claiming illustrating a participative and democratic planning culture, watching carefully some investments as the heritage.

2006-2012: Waad Project

Waad reconstruction project and the three previous reconstruction projects have many differences.

That is why it drew the attention of various observers. In the light of the framework presented in this study, these differences are related to some contextual elements, while others are related to political or professional choices.

At first, the ideological dimension of this project is very unique and strange. It is clearly stated that the reconstruction aims at preserving and reconstructing the Resistance society. On a larger scale, this action sought for an anti-imperialist goal and a critique of the neoliberal globalization, proven by the choices of the operational structure and the rejection of a funding through the market. This ideological orientation implies particular factors related to the settlement policy in this area. Indeed, the target population is composed of citizens and merchants of the area. In the projects related to downtown, the target public went beyond the citizens or economic actors of the center. It included metropolitan, national, and even international perspectives. It is not the case in Haret Hreik even if the commercial role of the area towards the neighboring towns in the southern suburbs was not disregarded. On the political level, the population is characterized by its political loyalty to Hezbollah, even if the citizens voted in Haret Hreik or in their cities of birth. The terms of the reconstruction in question are therefore crucial for the legitimacy of the party. This is a situation quite unique to the Lebanese context.

The reconstruction duration could not be compared to the previous reconstruction projects duration, except for the situation prevailed in 1977. The destruction duration was the 33-day war. This short duration, unlike the previous projects, including the downtown project, evoked live memories of the citizens determined to immediately return to normal. People didn't have time to make their lives in other places, in Lebanon or abroad.

Concerning the project duration, the persons in charge of Waad were very ambitious and clearly stated that: a quick return to the normal was their main concern. Thus, the reconstruction of a replica was considered as the best solution. Additional time wouldn't be consumed on complicated studies and on negotiations for the approval of new planning documents. De facto, the execution of the project in five years differed from the duration of Solidere project, as a large part of the area to be reconstructed is still empty or just backfilled.

Another element related to the planning temporality affects the choice: the lack of a town planning project for the region from the sixties. At that time, it was just an insignificant urban regulations imposed on the owners and not a development operation as the creation of a new centrality14 . The lack of ideas and pending projects are crucial to the decision of reconstructing a replica in the absence of other alternatives, which could influence the local or national authorities. Conversely, the reconstruction projects of other urban area sectors during the previous years, Solidere and Elissar, are considered as anti-models or repellents. As proved in this scope by the presentations of the persons in charge of the project or by the writings of Rahif Fayad, Waad project was conceived in order to be the opposite of Solidere on the ideological level, on the level of the relations with the citizens, considering the short duration of the project etc… Similarly, the experience of Elyssar is negatively perceived as the project has never been executed because of the disagreement with the government concerning the goals and the management of the project and because the perceived remodeling wouldn't have allowed the full relocation of the citizens and would have been pricey.

The urban fabric is characterized, as a result of the choices made in the name of faithful reconstruction, by minor modifications essentially related to the architecture. The plot canvas has been quite fully preserved. Some provisional amendments were executed (pavements, parking lots).

In general, apart from the existing public spaces, as pavements, new public spaces were not built despite the extreme density of the area: The lack of quality of the urban space has been totally reproduced.

Another feature unique to Waad project is related to funding and to the operational tools. Waad is sometimes presented as an Ngo, a non-governmental organization. It is true: Waad is related to the association, Jihad al-Binaa, thus reflecting the power of a well structured and professional political party. Moreover, this party is officially implanted in the territory, especially through municipalities: this fact distinguishes Jihad al-Binaa and Waad from other organizations which lack of any organic bond to political and administrative bodies. This structure has, competently and efficiently, guaranteed the follow-up and the coordination of the project as well as the management of the building site.

Funding of Waad project is also unique to the Lebanese context: It exclusively relies on financial transfers and doesn't include any auto-financing through the market. The reconstruction total cost is nearly of 400 M$. The government paid half of the cost as compensations for the damages reparation (a great part of these compensations remained to be paid in July 2012). These compensations indirectly reflect an international solidarity towards Lebanon (Stockholm and Paris III conferences in 2006 and 2007). However, the remaining sum is directly covered by Waad, which is provided additional funding from Hezbollah and from its own support networks among its allies or supporters in the world.

Another unique feature, very strange to the foreign observer, is the legal reconstruction frame. Despite the decree no. 631, dated August 2006, authorizing the reconstruction of a replica, but at that time the project was achieved, no law to regulate a posteriori the projects by the Parliament has been passed, even though urban planners have tried to abide to the previously existing rules, that is to say, building guidelines, building permits or regularizations certificates. This situation is very worrying because, as long as such a law is not approved; eligible parties are legally deprived of their rights, including the registration of their property in the land registry and all the related guarantees and warranties.

Considering the planning cultures in Lebanon, the originality of Waad as a non-governmental organization is not just because it is an association but because it is not related neither to the government (as a political instance) nor to the centralized government administrations.

The experience Waad proves that urban planning in Lebanon could be executed without and even against the government. In this regard, the reconstruction of Haret Hreik shares many similarities with the urban action in the red suburbs, fiefs of the French communist party in the major French cities; the primary objective of the communist municipalities is the stabilization of the people, involving the fulfillment of the inhabitants' expectations in terms of housing and basic amenities (very limited in the case of Waad, admittedly).

From this standpoint, the experience of Haret Hreik reconstruction is indeed in line with a municipaltyped logic. Certainly, it is not a municipal organization in the strict sense of the word but they are somehow similar. This situation is unique to Lebanon, as there are few urban planning projects in general or reconstruction projects in particular where political legitimacy is directly sought by the construction of living environment.

The persons in charge of Waad put forward the participation of the citizens in their housing and buildings development. However, if this issue is unique, its scope is restricted as the participation did not include greater urban conception, such as public spaces organization or town plan redevelopment, variables frozen at the start of the project by political constraints.

Conclusion

Within the framework of a workshop aiming at the evaluation of Waad project, not arbitrarily presented as "a unique experience", this evaluation based on reconstructions history in Beirut is of great importance. However, such an objective is risky considering the debates surrounding these reconstructions. Multiple registers of argumentation are mobilized, reliying on (geo)political, social, architectural or planning criteria which endlessly compare, oppose or bring them closer.

For that reason, the primary goal of this study was to set a conceptual framwork differentiating two axes of analysis and identifying on each one of them a series of criteria. The advantage behind this grid is to emphasize the similarities and differences and to classify them according to various factors such as the ideological options of the founder or the political actors, the geographical context of the reconstruction, the history of the places from the perception of the residents as well as of the urban history, the nature of the destructions and the social transformations which they caused, or the planning cultures which also define the project.

The scope of the current reading grid is wider than the case of Lebanon but, for demonstration needs, it is applied here on two levels: firstly, through the definition of the Lebanese planning cultures in general and secondly through the application of four reconstruction projects, two of which only were really implemented.

At the end of this analysis, the originality of Waad experience must be understood in a moderate way and according to several explanatory logics.

On a first level, Waad seems to be a unique experience by means of a political and ideological will: unlike Solidere, Waad is a reconstruction targeting the residents and tradesmen of the area, enabling them to return to reside there while preserving the memory of the place. Hence, a reconstruction similar to the what existed is privileged in a non-commercial approach. In doing so, on a larger scope, the project managers intend to preserve and rebuild the "resistance society". Through this act, the reconstruction takes a geopolitical sense of opposition to Israel and, consequently, to their American allies, and an ideological sense of refusal of neoliberal globalization-which is another way to mark the difference between Solidere and Waad, by refusing for example a real estate company and the project funding by the real estate market.

However, the analysis conducted also highlights other determinants of the originality of Waad which derive from the geographical, urban, and historical elements more than the political will. The localization of Haret Hreik in the urban area alters the reconstruction challenges. This neighborhood is not dedicated to centrality on the urban area level, thus limiting the possibilities to deeply transform the structures. From this point of view, the lack of alternative urban planning is significant. One can undoubtedly see that the government is neglecting the development of the capital southern suburbs. In fact, no other future than returning to the existing one was thus possible. Moreover, the particular political bond between Hezbollah and the local residents constituted a barrier to any attempt of profound area alteration and to any initiative which would have delayed the project and thus the return of the inhabitants. Furthermore, the suddenness of the destruction (33 days) was another reason to stick to a program of return to the immediately former state: the bond between the inhabitants and their living area was not strained; the memory remained sharp and not scrambled by other experiences.

In many ways, Waad project and downtown Beirut area reconstruction project in 1977 are similar. However, two factors are different and underline the importance of what has been called the planning cultures. Indeed, in 1977, the administration and the experts of the Lebanese urban planning expected many transformations of the downtown area. Even though the 1977 project was largely a draft of return to the normal and conservation of existing, it also included a desire of modernization. The continuous destruction and transformation of urban society (especially by migrations) gradually increased this desire until the almost complete alteration of the places by Solidere.

The second major difference between Waad project and the 1977 project is the place of the government in the Lebanese planning. In 1977, as a continuation of the Chehabist project, the experts in charge of the case were the representatives of a state-controlled culture of planning. This culture enabled the government and its technocracy defining the general interest, thanks to their professional skills and their perception of the economic needs of the country and the city. The statecontrolled culture is widely questioned with the Waad project: on the one hand, Hezbollah considers that the government is controlled by political opponents who primarily serve class interests and strategic visions with which no compromise seemed possible. On the other hand, in Lebanon, a decentralized non-governmental practice of urban planning seems to closely respond to the inhabitants' aspiration. The recent emergence of Lebanese municipalities illustrates this movement, even if it is limited and and rid of contradictions. The associative machinery of Hezbollah was able to take hold of these aspirations. Numerous professionals from outside the party had the same aspirations. Waad results from this mobilization which is both professional and territorialized: Hezbollah institutions such as Jihad al-Binaa are strongly enshrined within the southern suburb and have established bonds of organic complementarities with the municipalities15 .

For that reason, one could affirm that Waad represents a municipal type of urban planning.

But the paradox is that the de facto municipalization of urban planning remains implicit and infralegal at the expense of the inhabitants' rights. In fact, the regularization process remains until now unfinished-apparently due to the fault of the government. In addition, the municipal election process has become, in Lebanon, artificial due to the massive disconnection between the polling place and the place of residence. As a result, the inhabitants could not have a democratic control of their representatives.

At the end, the Waad experience appears to be unique and constitutes a major reference to the Lebanese urban planning, of which it illustrates some recent developments. The legalization of the operation a posteriori remains a major challenge to overcome. Once acquired, it will allow the banalization of the neighborhood and the return of normal daily life, through neighboring interactions, gradual transformations, or probably residential mobility outside the neighborhood. The reconstruction will become a memory rather than a sign of ostentation and distinction.

  This type of planning culture is becoming more popular in Lebanon because of the progressive development of municipalities in local planning. The role of municipal urban planners lies in 8 Refer to, voir Verdeil Eric, 2010, Beyrouth et ses urbanistes: une ville en plan, Beyrouth: Presse de l'IFPO, 362 p. 9 Refer to the analysis of Pierre-Arnaud Barthel, 2008, Faire du « grand projet » au Maghreb. L'exemple des fronts d'eau (Casablanca et Tunis),Géocarrefour, 2008, vol. Vol. 83, n°1, p. 25-34.

10

Refer to Lacoste Y., 1963, Un problème complexe et débattu: les grands ensembles, Bulletin de l'association des géographes français, 1963, p. 37-63. For a recent appraisal: Bacqué M.-H., Fol S., 1997, Le devenir des banlieues rouges, Editions L'Harmattan, 215 p.

Refer to, for this question, Roncayolo Marcel, 2002, Lectures de villes : formes et temps, Marseille, Éd. Parenthèses, 386 p.

Nasr J. L., 1996, Beirut/Berlin: Choices in Planning for the Suture of Two Divided Cities, Journal of PlanningEducation and Research, vol. 16, n°1,

Verpraet G., 2005, Les professionnels de l'urbanisme : socio-histoire des systèmes professionnels de l'urbanisme. Paris : Économica, Anthropos, 226 p.

Refer to Souami T., 2006, Liens interpersonnels et circulation des idées en urbanisme. L'exemple des interventions de l'IAURIF au Caire et à Beyrouth, Géocarrefour, 2006, vol.

80, n°3, p. 237-247.

For a decoding of the municipal action in Lebanon, refer to Farah J., 2011, Différenciations sociospatiales et gouvernance municipale dans les banlieues de Beyrouth : à travers l'exemple de Sahel AlMatn AlJanoubi et des municipalités de Chiyah, Ghobeiri et Furn AlChebbak, Université de Liège, 560 p.

See Al-Harithy, Howayda, éd. 2010. Lessons in Post-War Reconstruction: Case Studies from Lebanon in the Aftermath of the 2006 War. Routledge and Verdeil, Éric. 2013. « Beirut: the new front lines of urban research ». Metropolitics. http://www.metropolitiques.eu/Beirut-the-new-front-lines-of.html ; Verdeil, Éric. 2011. « Post-2006 reconstruction in Lebanon: a laboratory for new urban planning practices ». Metropolitics, octobre. http://www.metropolitiques.eu/Post-2006-reconstruction-in.html.

 13 A detailed analysis of the three reconstruction projects of Downtown Beirut is available in my PHD thesis, chap. 9 : Verdeil E., 2002, Une ville et ses urbanistes : Beyrouth en reconstruction, thèse de géographie, Université Paris I-Panthéon-Sorbonne, 646 p.

For the records, the projects of the governmental cities presented by Ecochard in 1961, and not supported by the government at that time, some parts of these projects were supposed to be implemented in Haret Hreik (See Eric Verdeil, 2010, Beyrouth et ses urbanistes.Une ville en plans (1943Une ville en plans ( -1975)), Beyrouth : Presses de l'IFPO, p. 125).

Refer to Harb M., 2010, Le Hezbollah à Beyrouth (1985-2005). De la banlieue à la ville, Karthala, 300 p.


Antoine Venant

Nicholas Asher

Cedric Dégremont

Credibility and its Attacks

Introduction

Dialogues occurring in non-cooperative settings often exhibit attempts at deception, such as misdirections or lies. In many contexts, such as, e.g., trials or political debates, the objectives of a conversation's participant cannot be expressed in terms of her and her opponent's beliefs toward the content of the different dialog moves. In such contexts, dialogues moves come with semantic commitments of their own and challenges based on other players' semantic commitments.

In a political debate, an agent A might ask a question to another agent B, even though A knows the answer to the question. In such a case A is just seeking for B's commitment to an answer. If B complies and provides an answer, it can be in A's interest to further challenge this answer, even knowing it is correct. What is crucial here, are the objective semantic commitments that agents can force out of each other, rather than the subjective beliefs of these agents about whether the content of these commitments actually occurs or not.

Addressing the above requires us: 1. to have a semantic theory of commitments in dialogues, 2. to determine semantically what constitutes an attack and 3. to distinguish between attacks from a semantic perspective.

In the next section, we define credibility more precisely and attacks on it, linking these to linguistic commitments. In section 3, we give some examples of attacks on credibility, while sections 4 and 5 flesh out the analysis. Section 6 describes related work. We conclude with some directions for the future in section 7.

Credibility and commitments

An attack on credibility can be thought of as exposing deceitful intention. But determining inten- * We thank ERC Research Grant 269427 for research support tions behind speech acts is a tricky business [START_REF] Hamblin | Imperatives[END_REF] we will not be getting into. The notions of credibility and attacks we are considering depends on overt and public linguistic commitments by speakers.

Using commitments, we now precise our notion of credibility: a dialogue agent i is not credible iff (i) it is shown for some ϕ that i has committed to ϕ that is absurd or clearly refutable (shown to be inconsistent with a prior claim of the agent or a background common assumption), and that it was plausibly in i's interest to commit to ϕ if ϕ is not attacked. An attack by player j on the credibility of i occurs iff j commits to the following: i has committed to ϕ, ϕ |= ψ, ψ is absurd or refutable, and it is in o's interest to commit to ψ, if ψ is not attacked. A move a by player i makes possible an attack on credibility iff it is discourse coherent for j to attach an attack on i's credibility to a.

Our notion of credibility differs considerably from that employed in the signaling games literature where credibility is defined in terms of beliefs, typically in equilibrium [START_REF] Farrell | Meaning and credibility in cheap-talk games[END_REF][START_REF] Franke | Relevance in cooperation and conflict[END_REF]. Our notion of credibility is defined in terms of commitments, agent's interests and logical consequence, none of which depend on how the message affects the agents' beliefs.

To flesh out our picture of credibility and attack, we need to explain our notions of consequence and interest or preference. We have two notions of consequence: ordinary, logical consequence and defeasible consequence. We will assume that our agents are logically (though not factually) omniscient and so if i commits to ϕ he publicly also commits to ψ if ψ is a logical consequence of ϕ (notation ϕ |= ψ). Agents also commit to implicatures that are defeasible but what we shall term normal consequences that interlocutors would draw upon learning that i commits to ϕ. Finally, implicatures may be more tentative, as when i draws attention to an alternative to some-thing to which he is explicitly committed. We'll assume that implicatures are modeled in a defeasible logic using a space of preferred models of the conversation. We also allow that some weak implicatures may exist only in some of the preferred models while stronger ones are true in all preferred models. We thus distinguish between the following three levels of commitment. -Non-defeasible commitment by i to ϕ: ϕ is a logical consequence of every possible interpretation of i's contribution. -Implicit defeasible commitment by i to ϕ: the "prefered" interpretations of i's contribution entail ϕ. -Weak implicit defeasible commitment by i to ϕ: some interpretations of i's contribution imply ϕ. Section 4 will provide more formal definitions.

We take preferences to be tied to a conception of rationality. In our framework, we will assume two conversational partners 0, 1 and a third party who observes and judges but does not participate in linguistic exchanges. We will refer to this third party as the jury. The jury should be thought off as an abstract procedural entity with an objective look on the conversation that serves in the process of modeling rationality. The jury's mecanisms also depend on some contextual parameters which are common knowledge among the players: for instance, at court, the jury should know that an "honnest" expert witness must not share interest with the defendent lawyer. To give another example, he should know also when some facts are irrefutable and known as such. With this notion of a jury, our players prefer moves which make them look good in the eyes of the jury and make the other look bad, or at least worse. An attack by i on a player j's credibility is a way to make j look less good. Part of i's looking good is to not make mistakes, to not invite attacks on her credibility, but to make herself look good a player must provide positive reasons for the position she favors. Mutatis mutandis for the preferences of player j. More generally: (i) our players must play moves that make them look good; (ii) if player i is rational, she will prefer moves that make possible moves that j cannot attack; (iii) between 2 moves that make i look good but make possible attacks, she will prefer the one with the more indirect or weaker damaging context, since a more indirect damaging consequence is one that has a rebuttal move that's not what I meant to say.

Linguistic examples and intuitions

In this section we offer some linguistic examples featuring different sorts of commitments and attacks on credibility. These examples involve not only commitments to propositions expressed by assertoric clauses but also to propositions involving rhetorical relations that link clauses, sentences and larger units together into a coherent whole. That is, players commit to a particular content and to its relations with what has been said before. In so doing a player may also commit to contents proferred by his conversational partner as in [START_REF] Asher | Logics of Conversation[END_REF].

Consider a case in which speaker A takes C's initial moves to be ambiguous.

(1) a. C: N. isn't coming to the meeting. It's been cancelled. b. A: Did you mean that N. isn't coming because the meeting's cancelled or that the meeting is cancelled as a result? c. C: As a result.

A's clarification question in (1)b presupposes that C's initial contribution was ambiguous between a result and an explanation move [START_REF] Devault | Managing ambiguities across utterances in dialogue[END_REF][START_REF] Purver | The Theory and Use of Clarification Requests in Dialogue[END_REF]. We take this to imply at least a weak implicature for both readings, either of which a conversational participant could have exploited. This is something we want to model, and we'll see in the next example how such implicatures are exploited by an interlocutor. Now consider the following example:

(2) a. C: N. isn't coming to the meeting. It's been cancelled. b. A: That's not why N. isn't coming.

He's sick. c. C: I didn't say that N. wasn't coming because the meeting was cancelled.

The meeting is cancelled because N. isn't coming.

This example illustrates how commitments embed. In (2)b A commits to the fact that C committed in (2)a to providing an explanation for why N isn't coming, even though (2)a is ambiguous.

Only such a commitment explains why A attacks that commitment in the way that he does by giving an alternative explanation. But in fact, C takes that commitment by A to have misinterpreted him; C commits in (2)c that he committed in (2)a to of-fering a consequence or result of N's not coming to the meeting. Note that while A attacks a move of C's in (2), he does not attack C's credibility in our sense. But neither does (2) provide a case of misleading implicature. However, the following example from [START_REF] Asher | Infinite games with uncertain moves[END_REF] does. During the Dan Quayle-Lloyd Bentsen Vice-Presidential debate of 1988, Quayle was repeatedly questioned about his experience and his qualifications to be President. Quayle's attempted to compare his experience to the young John Kennedy's (referred to below as Jack Kennedy to convey familiarity) in his answer.

(3) a. Quayle: ... the question you're asking is, "What kind of qualifications does Dan Quayle have to be president," [...] I have as much experience in the Congress as Jack Kennedy did when he sought the presidency. b. Bensten: Senator, I served with Jack Kennedy. I knew Jack Kennedy. Jack Kennedy was a friend of mine. Senator, you're no Jack Kennedy.

Implicatures play a key role in his example. Quayle argues, against the thesis that his little governmental experience would make him unsuitable for the presidency, that Kennedy before him, with as much experience as he have, was able to handle the presidency. But this answer to the question suggests an implicit comparison between the two politicians (both junior senators from a state, each with little governmental experience) and gives rise to the possibility of interpreting Quayle's move as a stronger commitment that he would likely be able to handle the presidency in the same way that John Kennedy handled his, which, if not challenged would serve Quayle's claim better. Bentsen seized upon this weak implicature of Quayle's contribution and refuted it, indirectly exposing to the audience the self-serving nature of the comparison.

Here's an attested example from [START_REF] Solan | Speaking of Crime: The Language of Criminal Justice[END_REF], in which a prosecutor (P) wants Bronston (B) to say whether he had a bank account in Switzerland or not, and Bronston does not want to make such a commitment for strategic reasons. But he defeasibly commits to an answer with (4)d in an attempt to avoid further questioning [START_REF] Asher | Strategic conversation[END_REF]. It is interesting to consider a continuation of this in which the prosecutor would indirectly attack this response in (4)d.

(5) Prosecutor: I would like to know whether you personally ever had an account there?

If Bronston is forced on the threat of perjury to answer affirmatively, his response in (4)d now looks pretty deceiving to the Jury. The natural thought arises: Bronston was trying to deceive us into thinking that he didn't have an account. Though the prosecutor didn't proceed as in ( 5), had he done so he would have successfully attacked Bronston's credibility.

For our final example, consider the following excerpt from a voir dire examination in [START_REF] Friedman | Rules of the Road: A Plaintiff Lawyers Guide to Proving Liability[END_REF]. As background, the plaintiff lawyer (LP) has been repeatedly coming back to questions about the division of a nerve during a surgery with the objective of getting the witness (D) to characterize the surgical operation as incompetent and mishandled. Repeatedly coming back to the topic wore D down, and the defense attorney (LD) was no help: [START_REF] Crawford | Strategic information transmission[END_REF] a. LP: And we know in addition to that, that Dr. These examples suggest two general methods of deception: moves that implicate propositions that can't be committed to explicitly for strategic reasons, and moves that trap agents into making commitments they should rationally refrain from.

Another feature of attacks is that generally they work gradually in damaging an opponent's credibility. Perhaps no one move succeeds on its own in convincing the jury that the opponent is duplicitous or incompetent; rather a series of moves gradually move a jury to a skeptical view of the opponent over the course of a conversation. The victory conditions for our players are to succeed in eventually moving the jury to a position in which the opponent is no longer credible.

Dialogue model

We need a dialogue model in order to analyze our examples and attacks on credibility in more detail. We've already seen that we need to model as part of a speaker's contribution not only its compositional semantics but also its illocutionary effects, in particular the implicit discourse links between utterances, as these can trigger or convey attacks on credibility. We will therefore build on [START_REF] Lascarides | Agreement, disputes and commitment in dialogue[END_REF], as SDRT already offers a formal, logic-based approach of dialogue content (semantics + illocutionary effects).

[15] models the semantics of dialogue by assigning to each conversational agents a commitment slate. Each commitment slate contains a list of propositions that an agent is committed to, which involve rhetorical relations as well as elementary propositions. [START_REF] Lascarides | Agreement, disputes and commitment in dialogue[END_REF] model explicit and implicit agreements and denials of one agent about another agent's commitments. However, the analysis of credibility threats requires that we go a step further. Conversational agents explicitly or implicitly refer to, and dispute, others' commitments. They attack their opponent's credibility by exposing inconsistencies in something they claim the opponent committed to or implicated, and defend against such attacks by denying a commitment to content that the opponent claims they committed to or implicated. We need to represent the commitments of all speakers from their own and their interlocutors' points of view, as in [START_REF] Stone | Grounding as implicature[END_REF]. Moreover, we need to represent arbitrary nesting of commitments explicitly. Recall example [START_REF] Asher | Strategic conversation[END_REF]. In (2)b A corrects C's prior utterance, and thereby commits that C is committed to a false proposition p (N. is not coming because the meeting is cancelled). C rejects A's correction. But what C rejects is not the proposition that corrects p, but A's commitment that C commited to p. Therefore, C also commits that A commits that C commits that p. Further, we need to distinguish between weak and strong commitments: when an agent tries to misdirect another, he might for instance give a weak commitment the look of a stronger one. Thus our dialogue model will add three things to [START_REF] Lascarides | Agreement, disputes and commitment in dialogue[END_REF]: explicit nested commitments, the commitments of each agent from every agents' point of view and explicit strong and weak commitments.

Conversations proceed as follows in our model: speakers alternate turns, each performing a sequence of discourse moves. Because we are interested in commitments and attacks, we will not import the full machinery of SDRT here. We will symbolize clausal contents within a propositional language, but incorporate labels for speech acts and discourse relations so that we can roughly express discourse-structures following [START_REF] Asher | Logics of Conversation[END_REF]. Crucially, however, our language allows us to embed discourse structures under 3 modal operators [ ],

and N . A discourse move for an agent i is defined as a discourse-level proposition labelled by a speech act identifier. A discourse-level proposition is either a base-level proposition, a formula expressing commitment over a discourse structure (i.e. i commits that a label have some particular content), or a complex formula R(π 1 , π 2 ) where R is a coherence-relation symbol and π 1 and π 2 are speech act labels. A complex formula recursively involves previously introduced speech acts labels. The modalities make the language more expressive, since we can express commitments of different agents to different contents for a single speech-act. The formula [π : γ] i states that agent i commits that the content of the speech act π is γ. Hence, she also commits that the speaker of π commits to the discourse proposition γ. Its dual, π : γ i , expresses the proposition that it is possible for i that the content of π is γ. N i ϕ means that i defeasibly commits to the contents of the for-mula ϕ. These modal operators express commitments over discourse structures. From this we retrieve commitments over informational content by looking at the content assigned to labels which are maximal for a given speaker. (labels that are not in the scope of another label of the same speaker): a speaker is committed to a content ϕ iff she commits the content of one of his maximal labels to be a proposition that entails ϕ.

Assume a set Φ of base-level propositions, a countably-infinite set of labels Π, a finite set of relation symbols R and a set of conversational agents I. In order to keep track of which agent x perform which speech act π, we assume Π partitioned in |I| disjoint subsets (Π i ) i∈I . We define spk(π) = the unique i ∈ X such that π ∈ Π i .

Γ(Φ) := ϕ | R(π 1 , π 2 ) | [δ] i | N i (δ) | δ i | ¬γ ∆ := π : γ | π :?(γ) | δ 1 ∧ δ 2
Where the γ i and δ i respectively range over Γ(Φ) and ∆, the π i and ϕ i respectively range over Φ and Π, and i and R respectively range over I and R.

Definition 1 (Model).

A model M is a tuple W, v, ( ⊲ x ) x∈X , < , where W denotes set of possible worlds, v : Φ → ℘(W ) a coloration, <: W → W 2 a function from worlds to partial orderings over W , and for each agent x, ⊲ x ⊆ W × W is a transitive and euclidean accessibility relation.

Our language has a dynamic semantics: the interpretation of a formula is context-change potential i.e. a relation between world-assigment pairs (w, σ). To account for polar question in our examples, we adopt a simplistic version of [START_REF] Groenendijk | Studies on the Semantics of Questions and the Pragmatics of Answers[END_REF] and take propositions to semantically denote a set of set of worlds (a proposition denotes a set of possibilities which is partitioned into equivalence classes raised by questions). For intance, the question whether p? partitions a set of world in two, those worlds at which p on the one hand, and those at which ¬p on the other. An assigment σ : Π × W → ℘(℘(W )) is a function that assigns a proposition as a set of set of worlds to a speech act label at a particular world. σ(w, π) is roughly the (partitioned) set of worlds in which the interpretation of π at world w is true. Given a model M, the function • M maps each formula δ of the language to a binary relation δ M over world-assignment pairs. Discourse-level assertoric propositions in Γ(ϕ) always leave the assignment component unchanged and act as filters that let through only the worlds at which the proposition is true. Discourse moves in ∆ on the other end modify the assignment. Another bit of needed machinery is for interpreting discourse relations. In our semantics each relation affects the contents assigned to its terms. Veridical relations like Explanation or Result will simply update the contextually given values to its terms with the semantic effects of the relation on those terms [START_REF] Asher | Logics of Conversation[END_REF]. Non veridical relations like Correction or alternation place constraints on the truth of the contents associated with the terms at worlds verifying the relation in question. We need some notation first: assume a model M = W, v, s, ( ⊲ x ) x∈X , < . Let p denote a dynamic proposition (i.e a relation between world/assigments pairs). Define |p| σ M as {w ∈ W | (σ, w) p (σ, w)} and |?p| σ M as {|p| σ M , W \|p| σ M }. Define Acc(w) as the set of set of world containing a single element which is the set of all worlds accessible from w: Acc x (w) = {{w ′ | w ⊲ x w ′ }}. Finally define the update operation ⋆ :

℘(℘(W )) × ℘(℘(W )) → ℘(℘(W )) as a ⋆ b = {x ∩ y : x ∈ a ∧ y ∈ b}.
Definition 2 (Semantics). Discourse propositions:

(w, σ) ϕ M (w ′ , σ ′ ) iff (σ, w) = (σ ′ , w ′ ) w ∈ v(ϕ) (w, σ) R(π 1 , π 2 ) M (w ′ , σ ′ ) iff (σ, w) = (σ ′ , w ′ )
and w ∈ I R (σ(π 1 , w), σ(π 2 , w))

(σ, w) [δ] x M (σ ′ , w ′ ) iff w = w ′ and ∀w ′′ w ⊲ x w ′′ → (σ, w ′′ ) δ M (σ ′ , w ′′ ) (σ, w) δ x M (σ ′ , w ′ ) iff w = w ′ and ∃w ′′ w ⊲ x w ′′ ∧ (σ, w ′′ ) δ M (σ ′ , w ′′ ) (σ, w) N x δ M (σ ′ , w ′ ) iff w = w ′ and ∀u (w ⊲ x u ∧ ∀v(w ⊲ x v → u ≥ w v)) → (σ, u) δ M (σ ′ , u)
Discourse moves:

(σ, w) π : γ M (σ ′ , w ′ ) iff w = w ′ and σ ′ (π, w) = σ(π, w) ⋆ |γ| σ M ⋆ Acc spk(π) (w) (σ, w) δ 1 ∧ δ 2 M (σ ′ , w ′ ) iff w = w ′ and (σ, w) δ 1 M • δ 1 M (σ ′ , w ′ )
Armed with this semantics for formulas, we can now define the commitments of each agent i at every initial prefix (sequence of turns) in the conversation. Because commitments will depend on discourse structure, we define commitments at maximal labels in the logical forms for the turns (those that are not within the scope of any other label). Given a logical form for n conversational turns (or the whole conversation), we can define the commitment of the players:

Definition 3. (σ, w) C i ϕ M (σ, w) iff ∃π(spk(π, i) ∧ maximal(π) ∧ ∀u(w ⊲ x u → σ(π, v) ⊆ |ϕ|))
We thus have a dynamic picture of how speakers' commitments evolve throughout a conversation. Examples revisited. We start with example (2). [START_REF] Lascarides | Agreement, disputes and commitment in dialogue[END_REF] would analyse the two first turns as in table

1 turn C's SDRS A's SDRS (2-a) π1 : ¬N π2 : ccl meeting π3 : Res(π1, π2) (2-b) π4 : ¬Exp(π1, π2) π5 : Corr(π3, π4)
Table 1: Analyisis of (2) following [START_REF] Lascarides | Agreement, disputes and commitment in dialogue[END_REF]. This is problematic, since A is committed to an absurdity. The semantic conditions of Corr(π 3 , π 4 ) require that the content of π 3 implies the negation of π 4 , but Res(π 1 , π 2 ) does not imply Exp(π 1 , π 2 ) (the two are even contradictory). Keeping with the same kind of tabular representation as [START_REF] Lascarides | Agreement, disputes and commitment in dialogue[END_REF] our proposal amounts to further divide each cell of the table above in two, introducing A ′ interpretation of C ′ s moves, and repeating this process potentially infinitely to express arbitrary nestings as in table 2. For readability, we simplify the table by recopying at each step only the moves whose interpretation is controversial in the nested cells. In our language (2) is analysed as:

[π 1 : ¬N ] c ∧ [π 2 : ccl meeting] c ∧ [π 3 : Res(π 1 , π 2 )] c ∧[π 4 : ¬Exp(π 1 , π 3 )] a ∧ [π 5 : π 3 : Exp(π 1 , π 2 ) c ∧ π 5 : Corr(π 3 , π 4 )] a ∧[[π 5 : π 3 : Exp(π 1 , π 2 ) c ] a ∧ π 6 : ¬C x (Exp(π 1 , π 2 )) ∧ π 7 : Corr(π 5 , π 6 )] c
Correcting move like π 5 triggers presupositions: here, a presuposition that c's move π 3 possibly commits him to the negation of π 4 's content, accomodated as part of π 5 's content. In the tabular representation, C's final move is:

C's SDRS C A π6 : ¬Cx(Ex(π1, π2)) π7 : Cor(π5, π6) C A π3 : Exp(π1, π2)
In (2), we have only encountered explicit commitments [ϕ] x . But in (1)b, A takes C's commitments to involve two possibilities, and he does not know which C has in fact committed to. Thus, in (1)b, A represents C's commitments as

[π 1 : ¬N ] c ∧ [π 2 : ccl meeting] c ∧ [π 3 : Res(π 1 , π 2 )] c ∧[π 5 : Clar-q(π 4 , π 3 )] a ∧ [π 5 : π 3 : Exp(π 1 , π 2 ) c ∧ π 5 : π 3 : Res(π 1 , π 2 ) c ] a
In (3), Bentsen (B) seizes on a weak implicature of Quayle's (Q). Q explicitly commits to a direct comparison between his experience in government and that of the young JFK, but B corrects a more general equivalence between the presidential promise of JFK and his own. If we symbolize the latter with JFK, we take B's turn to yield [π ′ : ¬JFK ∧ π : JFK q ∧ π 2 : Cor(π, π ′ )] b . We see that even a weak implicature is sufficient to warrant B's corrective move in π 2 . The success of this attack relies on the jury's decision on the admissibility of π : JFK q , i.e. the possibility of a commitent of q to JFK. Finally, in (6), we see that LP commits that D is committed to a discourse link between the defense attorney and his own self-correction:

[[π 1 :?p] lp ∧ π 2 : p ∧π 3 : QAP (π 1 , π 2 )] d ∧[π 5 : Obj(π 4 , π 3 ) ∧ π 9 : π 7 : Res(π 5 , π 6 ) d ∧ π 9 : [π 8 : Cor(π 3 , π 6 ) d ] lp C's SDRS A's SDRS π1 : ¬N π2 : ccl meeting π3 : Res(π1, π2) C A π3 : Exp(π1, π2) π4 : ¬Exp(π1, π2) π5 : Corr(π3, π4)
Table 2: Adding nested commitments Speakers choose the sequences of discourse moves they do because they want to convey commitments that will make them look good in the eyes of the Jury; they also want to make an opponent look bad if possible by attacking her weak points. We call this their winning condition. We will assume as in [START_REF] Asher | Infinite games with uncertain moves[END_REF] that speakers may have incomplete knowledge of the other players' moves, leading to nasty surprises as in [START_REF] Asher | Infinite games with uncertain moves[END_REF], where Quayle clearly didn't anticipate Bentsen's move in (3)b. A final desirable feature of the strategic model is that the moves open to a participant that lead her to her winning condition may decrease or even vanish if her credibility is repeatedly attacked. Thus the underlying framework of a sequential game is essential for analyzing conversation.

During play, a player has to weigh whether to make a move that makes her look good but that is risky in that it can be attacked; if the attack has no grounded rebuttal [START_REF] Dung | On the acceptability of arguments and its fundamental role in nonmonotonic reasoning, logic programming and n-person games[END_REF], the move could be disastrous. Further, when an opponent j makes a move involving an implicature it is up to the player i to decide whether it can be taken as a safe commitment in the sense of [START_REF] Asher | Strategic conversation[END_REF], and to exploit it in subsequent conversational moves, as the prosecutor of (4) does; and conversely j has to weigh whether the player will take the implicature on board or not, as one of i's commitments. If not, the deceptive move may fail if an opponent makes a request for an explicit version of an implicated commitment as in [START_REF] Cabrio | A Natural Language Account for Argumentation Schemes[END_REF].

All of these calculations depend on the effect of play on the Jury, who ultimately decides the winner according to positive points and lack of bad moves (inconsistencies or deceptions) on the part of i and other players. Our Jury entertains a space of possibilities concerning player types for the players and a probability distribution P over them. Our model is simple; we assume just two types for each player GOOD and BAD. At the start of the conversation the Jury entertains only the possibility that all players are GOOD; that is the probability distribution is such that P (BAD i ) = 1 -P (GOOD i ) = 0 for any player i. As the conversation proceeds, P (BAD i ) is successively updated given what has happened over the last turn; i.e. P n (BAD i ) = P n-1 (BAD i /t n ). As long as the opponent does not convincingly refute the arguments of i at n, P n (BAD i ) = P n-1 (BAD i ). However, a successful attack on, say, i by j at turn t n , which results in a refutation of an argument by i with no convincing rebuttal gets the Jury to update P via Bayesian conditionalisation such that P n (BAD i ) > P n-1 (BAD i ).

The effect of a higher probability on BAD i is that the positive reasons advanced by i are given a lower score; that is the effect of a bad reputationthe good things you say get discounted. Thus, if the positive arguments by i in her favor provide some positive score σ i , then the effect on the Jury at turn n is:

1 overall-score i n = P n (GOOD i )(σ i n ) (1)
Our model should also reflect the duplicitous nature of weak implicatures that agents don't dare put out as full commitments. So the update of the probability on P n (BAD i ) will depend on (i) the strength of the implicature, (ii) whether the attack is successful in so far as there is no rebuttal that refutes it. For weak implicatures, there is a rebuttal: you misinterpreted what I said; but it renders the move useless for the player. The upshot of our model is that agents pay dearly if their credibility is successfully attacked when they advance a weak implicature, as evidenced in the example [START_REF] Asher | Infinite games with uncertain moves[END_REF]. What exactly was Quayle's (DQ) mistake? It was that he weakly implicated that he was of the same caliber as JFK, and it is this implicature that Bentsen (B) seizes on and shows to be ridiculous. He also implicates that DQ insinuated the direct comparison without directly saying so, which is a deceptive move. B's attack was very successful, especially since DQ did not vigorously rejoin with you misinterpreted me unfairly. Our model considerably increases P n (BAD i ) conditional on B's attack, rendering DQ's successful points much weaker. Not only did B refute DQ's argument and expose his deceptive move, but he affected the overall outcome of the debate.

In example (4) on the other hand Bronston (B) carries off his strongly implicated commitment to an answer in (4)d without being challenged by the prosecutor (P). However, it was somewhat dangerous. Had P continued as in (5), B would have had to contradict N B (¬bank account) with [bank account] B , the two modal formulas being inconsistent. Bronston could have claimed that he had not understood the first prosecutor's question as being directly about him, but the response would have been weak and our intuition is that his credibility would have suffered. Example (6) exhibits a slightly different pattern: D has committed to there being no negligence in the operation, but in (6)b, he commits to the presupposition of the question that entails negligence. Conditional on such a contradiction, P (BAD R ) increases, but not much because it was a trick question. But when D attempts to retract his affirmative answer to LP's biased question, then pins on him reasoning that attacks his credibility as an impartial witness via a weakly implicated connection between LD's and D's contributions. At this point, P (BAD D ) increases considerably, and weakens D's testimony in the eyes of the Jury.

Our model predicts that as a player's credibility is repeatedly attacked and duplicitous moves are exposed, her credibility decreases monotonically. As a consequence, after a certain point the player may have no moves open to her that achieve her winning condition-the probability of her being of BAD type is now too high.

Related work

Our work assumes a commitment based view of conversation rather than one based on the internal, mental states of the participants [START_REF] Hamblin | Imperatives[END_REF][START_REF] Traum | Discourse obligations in dialogue processing[END_REF][START_REF] Traum | Computational models of noncooperative dialogue[END_REF] and builds on and complements the model proposed in [START_REF] Stone | Grounding as implicature[END_REF], which in turn extends [START_REF] Devault | Managing ambiguities across utterances in dialogue[END_REF]. They introduce a dynamic Bayesian model for discourse actions based on prior moves. Our paper is more limited in scope but also goes into more detail: our model details how attacks on credibility function with respect to various types of commitments that come from different kinds of discourse moves; we show that even in simple conversations levels of embedded commitments can be very complex (contrary to a suggestion of [START_REF] Stone | Grounding as implicature[END_REF]); and our Bayesian update on player types details a part of the picture of [START_REF] Stone | Grounding as implicature[END_REF].

Our model assumes a sequential game view of conversation, differing from extended signaling games [START_REF] Aumann | Long cheap talk[END_REF], and uses a notion of credibility which differs from the standard one in signaling games, according to which a message is credible iff its standardly accepted content understood as a set of evaluation points is a superset of its meaning in reflective equilibrium (roughly how the message content affects belief). In strategic environments of the sort we have in mind, signaling games have severe limitations: in our strategic contexts, a player will send a message only if it benefits him, but then that message will not benefit his opponent. In a signaling game, the opponent should rationally ignore it [START_REF] Crawford | Strategic information transmission[END_REF]. However, in a debate, it would be irrational to ignore the message of the opponent. Our notion of credibility does not mix belief and action in the way signaling games do, and is immune to this problem. A further problem with signaling games is that they assume common knowledge of the preferences of each player over moves. But if these are used to define or to guide credibility, then there is no room for maneuver or deception, which is manifest in our examples. However, our model leaves a place for a signaling game analysis between the Jury and the players, which we will pursue in future work.

Related to our work are also recent attempts to investigate argumentation in actual dialogue [START_REF] Cabrio | A Natural Language Account for Argumentation Schemes[END_REF]. Argumentation theory provides a framework for analyzing attacks and counterattacks [START_REF] Dung | On the acceptability of arguments and its fundamental role in nonmonotonic reasoning, logic programming and n-person games[END_REF]. We have given much more linguistic detail on how such attacks are carried out and how this can affect ones' strategy in conversation. On the other hand, we have presented a general model for credibility in strategic conversation. Different contexts may affect the parameters of the model that we have set up. For instance,2 sometimes the Jury may be a participant in the conversation in the sense that it is allowed to ask questions, sometimes not. Given a particular context, Jury might also function according to persuasion rules that are different from the simple one we have used in section 5. We have chosen simple settings to illustrate our model. Finally, we have not gone into the details of how particular conversational contexts may dictate specific linguistic forms of attacks and defense, e.g., [START_REF] Drew | Contested evidence in courtroom cross-examination: The case of a trial for rape[END_REF]. Our model is general enough, we believe, so that we can tune the parameters to fit the particularities of specific contexts.

Conclusions

In this paper, we have presented new notion of credibility and attacks on credibility that are relevant to conversations in strategic settings where interlocutor preferences may be opposed. We have developed a dialogue model extending both [START_REF] Lascarides | Agreement, disputes and commitment in dialogue[END_REF] and [START_REF] Stone | Grounding as implicature[END_REF] with a semantics for dialogue turns and commitments that allows for arbitrary nestings of commitments. We have also shown that this complexity is required to analyze many examples of dialogue with attacks on credibility.

  (4) a. P: Do you have any bank accounts in Swiss banks, Mr. Bronston? b. B: No, sir. c. P: Have you ever? d. B: The company had an account there for about six months, in Zurich.

The defendant was resisting LP's line of attack relatively well, but then made an error by agreeing to LP's loaded question, in which LP makes the proposition that is really at issue, that Dr. Tzeng was negligent, a presupposition by embedding it under a factive verb. This makes it difficult to answer for D the question in a straightforward way.

In future work, we plan to experiment with refinements of this basic idea, such as using updated probabilities to score continuations.

Thanks to a Semdial reviewer for this point.