The good of the (human) polis depends on the happiness of animals.
— VlCKI HEARNE, Animal Happiness
IN 1973, THE US Congress passed the Endangered Species Act (ESA), which directs federal agencies to protect endangered species and declares their conservation a national policy goal. According to Roderick Nash, this statute codified a new ethical consensus that nonhumans can enjoy rights, or at least moral status.1 Granted, according to the preamble, it protects endangered species only because such species are valuable to humans.2 Still, the ESA, along with the many other federal environmental statutes passed during this era, does seem to reflect a new sensibility, a sense that the nonhuman world has greater value than we had recognized and deserves greater protection. This new sensibility is particularly evidenced in American attitudes toward nonhuman animals. Not only have we developed a substantial and relatively well accepted body of laws aimed at protecting animal welfare, but a 2003 Gallup poll shows that the vast majority of Americans (96 percent) believe animals deserve some protection from harm and exploitation. Many think they deserve even more protection than they currently receive; a surprisingly high percentage of respondents (35–38 percent) supported the extension of laws protecting laboratory animals, and 62 percent supported the passage of strict laws protecting farm animals. Twenty-two percent were even willing to support a ban on hunting.3
Nash sees this new sensibility as an instance of ethical evolution, even ethical progress: the extension of our moral sensibilities to include nonhumans. He explains the ESA as evidence of “the relatively recent emergence of the belief that ethics should expand from a preoccupation with humans (or their gods) to