The quarrel about the human ability to know the world has been an important part of philosophy from its very beginning. It is not surprising that such importance increases when it is the relationship between society and the natural world that is dealt with. In fact, there is an obvious link between the question about nature’s nature and the principle of sustainability, so that a seemingly philosophical inquiry ends up being essential to political decision. However, such debate has so far been centred around an opposition – between realism and constructivism – which should be put into question. The reason is its inability to properly explain a fact which ought to be the standpoint of any debate around sustainability: the transformation of nature into human environment. Therefore, in order to make sense of the transformative interaction between society and nature, neither realism nor constructivism are as such convincing. A realistic turn in the constructivist account of nature is thus advisable.