Abstract : Currently, in an era in which uncertainty is prevalent, local planners seek to optimise social-spatial organisation. “Sustainable development” is thus seen as an innovatory framework, since it brings a new outlook to the notions of space and time, as well as highlighting the complexity of contemporary spatial organisation and the role of foresight in local development actions. It also provides means to adjust public stakeholders' decisions to the uncertainty of the latter's' consequences. Based on field observations of the local planning and development options taken up by Morocco in the early 2000s, this thesis questions the implications of an adjustment having control as its sole objective. Practices stemming from the choice of what was presented as a new discourse on action are critically analysed by focusing on both socio-spatial inequality and the heuristic value of the unthinkable in dealing with the long-term, inter-group relations and fairness. Several social theoretical concepts seldom cited in geographical discussion are interwoven (e.g., Rawls's Justice; Care; Jonas's human ontology and Precaution) in order to study the mechanisms of socio-spatial justice in a context of spatial reorganisation. This approach leads to a system of understanding based on an in situ dialogue between the uncertain and the unthinkable. The idea is developed that “sustainable development” is a transitional concept enlivening thought on the relationship between what is unknown when an action is undertaken and the quest for social justice.