Shelly Kagan on Animal Rights

In what is probably the broadest sense of the term, to say of something that it has moral rights is only to say that it has moral standing—that it counts from the moral point of view. In this sense, most of us believe that people and animals have rights of some sort, but books and rocks do not. That is to say, we think that people and animals matter, morally speaking, in their own right (unlike books and rocks). Put another way, if something has rights in this broad sense of the term, our treatment of it is not morally irrelevant, nor is it of mere derivative significance (due, perhaps, to possible effects on other things that do count in their own right).

(Shelly Kagan, Normative Ethics, Dimensions of Philosophy Series, ed. Norman Daniels and Keith Lehrer [Boulder, CO: Westview Press, 1998], 170-1 [italics in original])