By linking the notion of participatory democracy with theories of public space, the publicization of collective problems, the formation of publics and the main features of the deliberative paradigm, this research, which focuses on the revision of the Schéma d'aménagement et de développement de l'agglomération de Québec, tends to identify, based on the theory of justification developed by Luc Boltanski and Laurent Thévenot (1991) the general forms of public argumentation deployed in a conventional order framed by technical, institutional and political devices, but also the criteria of judgment and sense of justice enunciated in public spaces of expression and claim relatively independent of the agents of programming and regulation of the political order, and to which all actors have recourse in order to have their qualities and ways of doing things recognized by others (and most often, in principle, by everyone) (Boltanski, 2008).