A reciprocity framework is presented as an analysis of morality, and to explain and justify the attribution of moral rights and duties. To say an entity has rights makes sense only if that entity can fulfill reciprocal duties, i.e., can act as a moral agent. To be a moral agent an entity must (1) be self-conscious, (2) understand general principles, (3) have free will, (4) understand the given principles, (5) be physicallycapable of acting, and (6) intend to act according to (...) or against the given principles. This framework is foundational both to empirical and supernatural positions which distinguish a human milieu, which is moral, from a nonhuman milieu, which is not. It also provides a basis for evaluating four standard arguments for the rights ofnonhuman animals and nature-the ecological, the prudential, the sentimental, and the contractual. If reciprocity is taken as being central to the general concepts of rights and duties, then few animals, and no natural objects or natural systems, have rights and duties in an intrinsic or primary sense, although they may be assigned them in an extrinsic or secondary sense as a convenience in connection with human interests. Nevertheless, there are some animals besides humans - e.g., especially chimpanzees, gorillas, dolphins, and dogs - which, in accordance with good behavioral evidence, are moral entities, and sometimes moral agents. On the grounds of reciprocity, they merit, at aminimum, intrinsic or primary rights to life and to relief from unnecessary suffering. (shrink)