"Environmental Ethics: Values in and Duties to the Natural World," in Bormann, F. Herbert, and Stephen R. Kellert, eds., Ecology, Economics, Ethics: the Broken Circle, pages 73-96. New Haven, CT: Yale University Press, 1991. Online at: http://hdl.handle.net/10217/37180

Environmental ethics stands on a frontier, as radically theoretical as it is applied. Alone, it asks whether there can be nonhuman objects of duty. Animals, plants, endangered species, ecosystems, and even Earth are progressively unfamiliar as objects of duty, and puzzles arise both for theory and practice. Answers to such questions are as urgent as any humans face, and intimately related to the four principal issues on the world agenda: peace, population, development, and environment.