Since the inception of their subject as a distinct area of study in philosophy, environmental ethicists have quarreled over the choice of entities with which an environmental ethic should be concerned. A dichotomous ontology has arisen with the ethical atomists, e.g., Singer and Taylor, arguing for moral consideration of individual organisms and the holists, e.g., Rolston and Callicott, focussing on moral consideration of systems. This dichotomous view is ecologically misinformed and should be abandoned. In this paper, I argue that the (...) organization of the natural world, as viewed by some ecologists and evolutionary biologists, is structured on various levels that are not reducible to one another. This hierarchical view, expressed by Salthe and Eldredge, provides the most complete and accurate ontology for environmental ethics. (shrink)