  While accepting that we may have moral obligations with respect to or regarding entities in the non-human world, Routley (1973, 19) and Routley and Routley (1980a, 174ff) deny that this entails our having obligations to them and deny, too, their having correlative rights. Sylvan rejects such an extension of rights to non-human entities. For this reason, he takes the “new environmental ethic” to “differ markedly” from alternatives like Leopold’s land ethic. As it developed, it also differed markedly from most forms of utilitarianism for a broad range of reasons, arguing instead for a deontologically constrained “optimisation approach to value theory”. (See Routley and Routley 1985; Sylvan 1992.) Variants of Last Man counterexamples to traditional Western ethics are also taken to show that the distribution of intrinsic value extends beyond sentient individuals—contra “animal liberationists” (1980a, 125) like Singer—so that “candidates for value … include all objects” (1980a, 140).