This paper analytically characterizes the four main environmental sustainability paradigms (i.e., WS, weak sustainability; AG, a-growth; DG, de-growth; and SS, strong sustainability) by introducing uncertainty about future preferences for consumption and future technologies. SS represents an ethical approach because of its maximum aversion to inter-generational inequality of resources, whereas DG depicts preference changes, AG depicts technology changes, and WS represents the reference paradigm without accounting for preference or technology changes. By comparing the costs and benefits of these paradigms, solutions derived for the whole parameter domains based on data for a globally representative individual suggest that whenever environmental sustainability is pursued for welfare reasons within a utilitarian perspective (i.e., WS, AG, DG), it is not worth pursuing. In contrast, if environmental sustainability is achieved for ethical reasons within an egalitarian perspective (i.e., SS), it is worth pursuing, even with an increased world population. In terms of feasibility (i.e., whether there are realistic parameter values such that a given sustainability paradigm can achieve its goal), solutions are ranked ethics > preference > technology (i.e., SS > DG > AG), whereas WS is unfeasible. Thus, WS, AG, and DG are inconsistent sustainability paradigms, SS empirically solves the theoretical dispute on absolute rights, and environmental sustainability must be treated as an ethical issue. A conceptual discussion about environmental ethics and a statistical analysis based on panel data at a country level support the same insights. In terms of reliability (i.e., whether there are national policies or international agreements which can support a feasible sustainability paradigm), SS could be enforced by a global environmental agreement, supported by 66/55% of governments (i.e., top-down approach) and by 56/51% of citizens (i.e., bottom-up approach), in the most certain/uncertain scenarios, respectively.