Christine M. Korsgaard presents a compelling new view of humans' moral relationships to the other animals. She defends the claim that we are obligated to treat all sentient beings as what Kant called "ends-in-themselves". Drawing on a theory of the good derived from Aristotle, she offers an explanation of why animals are the sorts of beings for whom things can be good or bad. She then turns to Kant's argument for the value of humanity to show that rationality commits us to claiming the standing of ends-in-ourselves, in two senses. Kant argued that as autonomous beings, we claim to be...