In Ted Honderich (ed.), The Oxford Companion to Philosophy, Oxford, 1995, pp. 35-36
In Western ethics, non-human animals were until quite recent times accorded a very low moral status. In the first chapter of Genesis, God gives human beings dominion over the animals. In the Hebrew Bible, this dominion was moderated by some injunctions towards kindness - for example, to rest one's oxen on the sabbath. The Christian scriptures, however, are devoid of such suggestions, and Paul even reinterprets the injunction about resting one's oxen, insisting that the command is intended only to benefit humans. Augustine followed this interpretation, adding that Jesus caused the Gadarene swine to drown in order to demonstrate that we have no duties to animals. Aquinas denied that we have any duty of charity to animals, adding that the only reason for us to avoid cruelty to them is the risk that cruel habits might carry over into our treatment of human beings.
Descartes's views were even more hostile to animals than those of his Christian predecessors. He regarded them as machines like clocks, which move and emit sounds, but have no feelings. This view was rejected by most philosophers, but Kant went back to a view similar to that of Aquinas when he held that animals, not being rational or autonomous, were not ends in themselves, and so the only reason for being kind to them is to train our dispositions for kindness toward humans. It was not until Bentham that a major figure in Western ethics advocated the direct inclusion of the interests of animals in our ethical thinking.
The debate over the moral status of animals remained peripheral to philosophical thinking until the 1970s, when a spate of books and articles led to a vigorous and continuing debate. Peter Singer compared speciesism with racism and sexism, and urged that there is no good reason for refusing to extend the basic principle of equality - the principle of equal consideration of interests - to non-human animals. Singer argued specifically against factory farming and animal experimentation, and urged that, where there are nutritionally adequate alternatives to eating meat, the pleasures of our palate cannot outweigh the suffering inflicted on animals by the standard procedures of commercial farming; hence vegetarianism is the only ethically acceptable diet. On animal experimentation, Singer urged that, in considering whether a given experiment is justifiable, we ask ourselves whether we would be prepared to perform it on an orphaned human being at a mental level similar to that of the proposed animal subject. Only if the answer was affirmative could we claim that our readiness to use the animal was not based on a speciesist prejudice against giving the interests of non-human animals a similar weight to the interests of members of our own species.
Other contemporary philosophers have reached similar, or even more uncompromising, conclusions on a different philosophical basis. Tom Regan, for example, argued that all animals - or at least mammals above a certain age - are 'subjects of a life' and therefore have basic rights. Eating animals and performing harmful experiments on them are, he holds, violations of these rights.
In addition to giving rise to a heated philosophical debate, these writings are unique in modern academic philosophy in that they have sparked and continue to influence a popular movement. Major animal liberation and animal rights organizations have developed in many countries, taking their inspiration from the writings of academic philosophers like Singer and Regan, and have made many people more aware of the ethical issues involved in our relations with animals.
Ted Benton, Natural Relations: Ecology, Animal Rights, and Social Justice (London, 1993).R. G. Frey, Interests and Rights: The Case Against Animals (Oxford, 1980).
Tom Regan, The Case for Animal Rights (Berkeley, Calif., 1983).
Tom Regan and Peter Singer (eds.), Animal Rights and Human Obligations (Englewood Cliffs, NJ, 1989).
Peter Singer, Animal Liberation (New York, 1975; 2nd edn. 1990).