In this article, it is argued that in the actual world, even if not in all possible worlds, sentience is both a necessary and sufficient condition for having moral standing. In arguing for this conclusion, the concepts of sentience and moral standing are explained. Five kinds of interest are then differentiated—functional, biotic, sentient, sapient, and self-conscious. It is argued that having sentient interests, rather than merely any interests, is what grounds moral standing. However, determining who has moral standing is only a beginning. Once we know whose interests we need to consider, we still need to know what interests need to be considered. We also need to know what considering those interests implies. Those questions are engaged in the remainder of this article.
