rights, primarily against being killed and being treated cruelly, that are thought to be possessed by higher nonhuman animals (e.g., chimpanzees) and many lower ones by virtue of their sentience. Respect for the welfare of animals is a precept of some ancient Eastern religions, including Jainism, which enjoins ahimsa (“noninjury”) toward all living things, and Buddhism, which forbids the needless killing of animals, especially (in India) of cows. In the West, traditional Judaism and Christianity taught that animals were created by God for human use, including as food, and many Christian thinkers argued that humans had no moral duties of any kind to animals, even the duty not to treat them cruelly, because they lacked rationality or because they were not, like Man, made in the image of God. This view prevailed until the late 18th century, when ethical philosophers such as Jeremy Bentham applied the principles of utilitarianism to infer a moral duty not to inflict needless suffering on animals. In the latter half of the 20th century, the ethical philosopher Peter Singer and others attempted to show that a duty not to harm animals follows straightforwardly from simple and widely accepted moral principles, such as “It is wrong to cause unnecessary suffering.” They also argued that there is no “morally relevant difference” between humans and animals that would justify raising animals, but not humans, for food on “factory farms” or using them in scientific experiments or for product testing (e.g., of cosmetics). An opposing view held that humans have no moral duties to animals because animals are incapable of entering into a hypothetical “moral contract” to respect the interests of other rational beings. The modern animal-rights movement was inspired in part by Singer's work. At the end of the 20th century, it had spawned a large number of groups dedicated to a variety of related causes, including protecting endangered species, protesting against painful or brutal methods of trapping and killing animals (e.g., for furs), preventing the use of animals in laboratory research, and promoting what adherents considered the health benefits and moral virtues of vegetarianism.
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