Advocates oppose the assignment of moral value and fundamental protections on the basis of species membership alone—an idea known since 1970 as speciesism, when the term was coined by Richard D. Ryder—arguing that it is a prejudice as irrational as any other. They maintain that animals should no longer be viewed as property or used as food, clothing, research subjects, entertainment, or beasts of burden. Multiple cultural traditions around the world—such as Animism, Taoism, Hinduism, Buddhism, and Jainism—also espouse some forms of animal rights.
In parallel to the debate about moral rights, animal law is now widely taught in law schools in North America, and several prominent legal scholars support the extension of basic legal rights and personhood to at least some animals. The animals most often considered in arguments for personhood are bonobos and chimpanzees. This is supported by some animal rights academics because it would break through the species barrier, but opposed by others because it predicates moral value on mental complexity, rather than on sentience alone.
Critics of animal rights argue that nonhuman animals are unable to enter into a social contract, and thus cannot be possessors of rights, a view summed up by the philosopher Roger Scruton, who writes that only humans have duties, and therefore only humans have rights. Another argument, associated with the utilitarian tradition, is that animals may be used as resources so long as there is no unnecessary suffering; they may have some moral standing, but they are inferior in status to human beings, and any interests they have may be overridden, though what counts as "necessary" suffering or a legitimate sacrifice of interests varies considerably. Certain forms of animal rights activism, such as the destruction of fur farms and animal laboratories by the Animal Liberation Front, have also attracted criticism, including from within the animal rights movement itself, as well as prompted reaction from the U.S. Congress with the enactment of laws allowing these activities to be prosecuted as terrorism, including the Animal Enterprise Terrorism Act.
Aristotle argued that animals lacked reason (logos), and placed humans at the top of the natural world, yet the respect for animals in ancient Greece was very high. Some animals were considered divine, e.g. dolphins. The 21st-century debates about animals can be traced back to the ancient world, and the idea of a divine hierarchy. In the Book of Genesis 1:26 (5th or 6th century BCE), Adam is given "dominion over the fish of the sea, and over the fowl of the air, and over the cattle, and over all the earth, and over every creeping thing that creepeth upon the earth." Dominion need not entail property rights, but it has been interpreted, by some, over the centuries to imply ownership.
Contemporary philosopher Bernard Rollin writes that "dominion does not entail or allow abuse any more than does dominion a parent enjoys over a child." Rollin further states that the Biblical Sabbath requirement promulgated in the Ten Commandments "required that animals be granted a day of rest along with humans. Correlatively, the Bible forbids 'plowing with an ox and an ass together' (Deut. 22:10–11). According to the rabbinical tradition, this prohibition stems from the hardship that an ass would suffer by being compelled to keep up with an ox, which is, of course, far more powerful. Similarly, one finds the prohibition against 'muzzling an ox when it treads out the grain' (Deut. 25:4–5), and even an environmental prohibition against destroying trees when besieging a city (Deut. 20:19–20). These ancient regulations, virtually forgotten, bespeak of an eloquent awareness of the status of animals as ends in themselves", a point also corroborated by Norm Phelps.