Using the three streams of radical environmental philosophydeep ecology, ecofeminism, and social ecologythis study highlights the subtle and complex environmental ethic in Cormac McCarthys southern novels. It also reassesses the critical consensus that these works are expressions of existentialist or nihilistic philosophy. By delineating the different relationships that McCarthys heroes and antiheroes have with nonhuman nature, an ecocritical analysis views their alienation as the effect of their separation from nonhuman nature. At the root of this alienation is an anthropocentric and mechanistic mode of thinking that is dominant in Western philosophy and that this study defines as Cartesian. While McCarthys environmentalist heroes are persecuted by Cartesian institutions and displaced from the land on which they have defined themselves and made meaning, his Cartesian anti-heroes represent extreme manifestations of Cartesian thinking. McCarthys environmentalism is as much a critique and indictment of Cartesian thinking as it is a portrayal of the value of a life lived in close contact with nonhuman nature.