Argument: Humans are obligated to cause animals no pain or suffering
Jeremy Bentham - "The question is not, 'Can they reason?' nor, 'Can they talk?' but rather, 'Can they suffer?'"
A summary of Peter Singer's main premise of equality by Michael Pollan in a New York Times Magazine Article entitled, "An Animal's Place" (November 10th, 2002) - "Singer's argument is disarmingly simple and, if you accept its premises, difficult to refute. Take the premise of equality, which most people readily accept. Yet what do we really mean by it? People are not, as a matter of fact, equal at all--some are smarter than others, better looking, more gifted. "Equality is a moral idea," Singer points out, "not an assertion of fact." The moral idea is that everyone's interests ought to receive equal consideration, regardless of "what abilities they may possess." Fair enough; many philosophers have gone this far. But fewer have taken the next logical step. "If possessing a higher degree of intelligence does not entitle one human to use another for his or her own ends, how can it entitle humans to exploit nonhumans for the same purpose?"
This is the nub of Singer's argument, and right around here I began scribbling objections in the margin. But humans differ from animals in morally significant ways. Yes they do, Singer acknowledges, which is why we shouldn't treat pigs and children alike. Equal consideration of interests is not the same as equal treatment, he points out: children have an interest in being educated; pigs, in rooting around in the dirt. But where their interests are the same, the principle of equality demands they receive the same consideration. And the one all-important interest that we share with pigs, as with all sentient creatures, is an interest in avoiding pain."
Katerina Apostolides & Lea Oksman. "Man's Dominion over the Animals". The Yale Free Press. Winter 2004 - "Animals are entitled to a certain amount of dignity and respect—the dignity not to be put in a microwave, exposed to toxic chemicals, or have food stuffed through a pipe down their throats. Perhaps the most serious argument against their legal protection—the potential threat to human medical research—has become increasingly irrelevant due to technological advances. On the other hand, genetic technology has vastly increased our power to exploit and mistreat animals, by creating mutant and hybrid animals with no dignity to their existence.
These factors compel us to take the animal rights movement seriously. Above all, we should not turn the fact of being human into a license for inhumane behavior."
Jean-Jacques Rousseau (1712–1778) argued in Discourse on Inequality in 1754 that animals should be part of natural law, not because they are rational, but because they are sentient: “[Here] we put an end to the time-honoured disputes concerning the participation of animals in natural law: for it is clear that, being destitute of intelligence and liberty, they cannot recognize that law; as they partake, however, in some measure of our nature, in consequence of the sensibility with which they are endowed, they ought to partake of natural right; so that mankind is subjected to a kind of obligation even toward the brutes. It appears, in fact, that if I am bound to do no injury to my fellow-creatures, this is less because they are rational than because they are sentient beings: and this quality, being common both to men and beasts, ought to entitle the latter at least to the privilege of not being wantonly ill-treated by the former."
Thomas Young, Humanity to Animals. "On Cruelty to Animals, in Sports Common to Men and Boys." 1798 - "Bull-baiting, Cock-fighting, and Throwing at Cocks; all of which the less need be said, as so little can be brought forward in their defense. It may be safely affirmed of all of them, that they are the sources of much useless and unnecessary pain to animals, and therefore we should want no other reason for condemning them."