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Most scientific approaches aim at elucidating a unique order to obtain a scientific image of their object. This strategy revealed efficient in most cases but led researchers to ignore phenomena resulting from the composition of several orders, each time this composition is not an accessory feature of reality but a core one. Another strategy is then to be chosen, which takes the plurality of orders as a basic feature of the reality to grasp. The type of plurality considered in the paper is the one resulting from the justification theory and its application to environmental and sustainable development issues. Several questions are tackled. What is the status of the concept of natural patrimony? What is the destiny of economic assessment in the context of environmental conflicts? Shall we consider sustainable development as a new legitimate social order of justification? What does a fair and equitable distribution of greenhouse gas emission rights look like? An examination of these questions demonstrates how much the assumption of plural social orders may give deep insights on key issues.