In recent years, epistemological debates in urban planning have been revitalised. This is reflected in the current state of French-speaking scientific literature with the publication of Cahiers Ramau (Cohen and al., 2018), some of whose articles call for a renewal of pedagogy (Huchette and al., 2018), and the issue of the journal Territoire en mouvement published the same year entitled "Formation à l'urbanisme et à l'aménagement" (Douay and al., 2018) as well as with the issue of the European Journal of Social Science (Bognon and al., 2018) following the symposium "Champ Libre : aménagement et l'urbanisme à l'épreuve des cadres théoriques" (2016). Debates are also fed into professional journals such as Tous urbains (Nov. 2018) where we talk about "upside down knowledge" and "training awaiting reinvention" (Lussault and al., 2018). Similarly, like Cybergeo's Current Issues on "City Professions" (Matthey and al., 2016-2018), there are many working papers and other blog articles on the subject. On reading these debates, a question crystallizes like a Gordian knot that is very difficult to decide: is the "end of urban planning" written (Faburel, 2018) or is urban planning being rewritten?

Strongly linked to institutional issues, the terms of this debate are quite different in the context of international publications. Thus, the question of the future of urban planning, both from the point of view of research and training, is being re-examined on the international scene in the face of major contemporary crises: climate change (Bulkeley, 2012), the collapse of biodiversity (Shochat and al., 2010), resource depletion (Kennedy and al., 2007), fiscal and financial austerity (Donald and al., 2014), social injustice (Soja, 2009), health issues (Giles-Corti and al., 2016) and migration (Back, 2018). In parallel with these crises, the relationship to urban planning tools and procedures is also changing. These include digital knowledge (Büscher, 2016), big data and open access as well as various participation experiences (Roberts, 2015). These are all contextual and procedural changes that deeply destabilize urban planning and that require us to face the corresponding challenges. How can we envisage the future of urban planning?

While the feeling of an acceleration of time is shared, projecting oneself into the future is not an easy task. We hypothesize here that this difficulty is not unrelated to the difficulty of referring to the past. This is why the questions that arise in urban planning must be the subject of attention, both introverted and extroverted on the discipline in order to develop new modalities of "active reflection" and "reflexive action" (Devisme, 2010). To this end, this conference offers the dual opportunity to highlight the issues and problems of urban planning and to take a step back from them. In this sense, the end of urban planning is not written. This contemporary moment, this change of era, may even be the opportune moment by which the speed of events allows us to travel differently through urban planning discipline and its regimes of traces (Derrida, 1972). As such, urban planning is not only the imprint of a culture, territory or era, but what shapes social systems and allows them to project themselves into time and space. Each current, theory or doctrine of urban planning adopts a certain economy of traces, which fixes practices and meanings, by ordering the emergence, hybridization and circulation of models. As a point of convergence between knowledge, actors and techniques, the traces thus testify to an organization of the collective through the organization of thought. From ambitions and intangible narratives to the city as a tangible message, one of the major functions of urban planning then lies in the transmission of traces to the collective memory in the form of a permanent document of its history, the urban. Recalling such elements means placing the question of the meaning of urban planning at the heart of the reflection proposed by this conference. The retrospective of the theories and practices of urban planning - both at the teaching and research levels - aims here to provide a reading of the trace regimes of urban planning. Against a monolithic conception of history, we wish on the contrary to underline the effects of accelerations, ruptures, revivals, accentuating the heterogeneity of the times and knowledge constituted over the last fifty years, bringing out the different regimes of trace to allow new crystallizations. It is this principle of a reading of urban planning that guides the orientation of this conference and the choice of thematic sessions where critical retrospective is central.

More than a collection of experiences or a catalogue, however well reasoned, of projects, the sessions aim to introduce a whole series of issues in the cultural, technical and political history of urban planning. In a context of disrupting access to knowledge in the digital age, the complexity of urban "palimpsest" (Corboz, 2001) combined with the complexity of socio-environmental issues (Latour, 2017) means that, although hyper-connected, we often find ourselves in an ocean of disparate information. This information itself sometimes lacks connections, meaning and direction. It is therefore important to go beyond the fragmentary experience of urban planning, to rearm the understanding of the systemic coherence of a whole, and to establish a real knowledge mapping in order to make this critical retrospective a moment of disciplinary reflexion.

While everything pushes urban planning to look to the future, this conference proposes to reverse the view and observe the discipline - its teachings as well as its research – in the lght of the last fifty years. This approach is nevertheless in keeping with current events, as many urban planning institutes are celebrating their 50th anniversary in 2019 - in particular Aix, Grenoble and Tours - (Buyck et al., 2018). Moreover, proposing a periodization - quite relative - that takes into account the year 1968 is not insignificant. While the younger generation of urban planners is tempted to cut off links with the "conventional" society and practice of urban planning (Goodman, 1971) is taking place in parallel with the institutionalization of training in this field. At the same time, an ecological approach is emerging that goes beyond criticism of official urban planning to question the relationship of industrial society with natural space (Borasi et al., 1973). Focused on the decision-making processes that affect the urban and its exponential expansion, post-1968 urban planning carries within it the terms of an epistemological debate of striking topicality. In other words, this conference is an exercise to update the motivations and rhetorical strategies of urban planning, conducted using the techniques of urban criticism and urban planning. Through the analysis of pedagogical experiences, research contracts, biographical and/or institutional trajectories, theoretical and/or (video-)graphic works, etc., we are interested in urban planning as a reformulation of the urban. Neither purely inductive nor deductive, urban planning - a change of point of view that leads to action - cannot be reduced to the transformations it induces. Following its process of enunciation - strongly intertwined with the urban - to the trace, the ambition of this conference is to show the urban in all its dimensions and thus to allow us to understand urban and urban realities, practices and theories in a very new light.