Degrowth scholars argue that drastic reductions in Western societies' economic activities are necessary and desirable for sustainability, justice, and democracy. But this normative statement is paradoxical, for degrowth’s necessity and desirability presuppose two mutually inconsistent premises. Such a paradox illustrates the troubled relationship between degrowth’s intellectual sources, whose coherence is assumed. On the one hand, degrowth would be necessary because of the inherent incompatibility between ecosystem integrity, the entropy law, and our current energy-intensive, complex, and anthropocentric modern societies. Thus, transitioning to ecocentric and low-entropy social organizations would be the only way to guarantee a just and genuinely prosperous human survival and endurance. Besides, degrowth’s idea of a repoliticized and autonomous society assumes that the political debate on environmental sustainability is a contentious arena where alternative and disputable visions confront each other; and that humans should give themselves their own rules consciously out of external constraints. But if natural systems’ thermodynamic and ecological limits force modern economies to shrink -democratically or not - as some degrowth scholars argue, it is conceptually unfeasible to claim that degrowth is more appealing than competing conceptions of justice and sustainability. To overcome this paradox, I argue that degrowth’s normative value is in its most aspirational and non-deterministic vein. I justify this claim on two grounds. First, degrowth’s ethical sense of limitation might be justified to further human flourishing value toward protecting human capabilities. Second, a call for human restraint may correspond to a preference for a desired state of ecosystems to preserve their aesthetic, cultural, and spiritual value for local communities. Both contributions allow us to place politics clearly above metaphysics in the sustainability debate.