What rational justification is there for conceiving of all living things as possessing inherent worth? In , Paul Taylor draws on biology, moral philosophy, and environmental science to defend a biocentric environmental ethic in which all life has value. Without making claims for the moral rights of plants and animals, he offers a reasoned alternative to the prevailing anthropocentric view--that the natural environment and its wildlife are valued only as objects for human use or enjoyment. provides both a full account of the biological conditions for life--human or otherwise--and a comprehensive view of the complex relationship between human beings and the whole of nature. This classic book remains a valuable resource for philosophers, biologists, and environmentalists alike--along with all those who care about the future of life on Earth. A new foreword by Dale Jamieson looks at how the original 1986 edition of has shaped the study of environmental ethics, and shows why the work remains relevant to debates today.