Abstract This article introduces an intuitive conservation dilemma called the Canyon Dilemma: Is it possible to condemn the mining of the Grand Canyon, even by a poor generation, while also permitting this generation’s mining of an unremarkable small canyon? It then argues that not one of several prominent theories of environmental justice, including various forms of egalitarianism, welfarism, deep-ecological theories, communitarianism and free-market environmentalism, can navigate this dilemma. The article concludes by highlighting the dilemma-navigating potential of the equal-claims idea – the idea that the natural world is something to which every human being, present and future, has an equal, substantive claim.