The term speciesism is used mostly by advocates of animal rights, who believe that it is irrational or morally wrong to regard animals (which many people believe are sentient beings) as objects or property. Some philosophers and scientists disagree with condemnation of speciesism. They argue that speciesism is an acceptable position and behavior. Philosophers Tom Regan and Peter Singer have both argued against the human tendency to exhibit speciesism. Regan argues that all animals have inherent rights and that we cannot assign them a lesser value because of a perceived lack of rationality, while assigning a higher value to infants and the mentally impaired solely on the grounds of being members of a certain species. Singer's philosophical arguments against speciesism are based on the principle of equal consideration of interests.
Richard Dawkins briefly touches on the subject in The Blind Watchmaker and The God Delusion. He compares former racist attitudes and assumptions to their present day speciesist counterparts. In the chapter "The one true tree of life" he argues that it is not just zoological classification that is saved from awkward ambiguity by the extinction of intermediate forms, but also human ethics and law. He describes discrimination against chimpanzees thus:
Such is the breathtaking speciesism of our Christian-inspired attitudes, the abortion of a single human zygote (most of them are destined to be spontaneously aborted anyway) can arouse more moral solicitude and righteous indignation than the vivisection of any number of intelligent adult chimpanzees! [...] The only reason we can be comfortable with such a double standard is that the intermediates between humans and chimps are all dead.
Dawkins more recently elaborated on his personal position towards speciesism in a live discussion with Peter Singer at The Center for Enquiry on December 7, 2007.
What I am doing is going along with the fact that I live in a society where meat eating is accepted as the norm, and it requires a level of social courage which I haven’t yet produced to break out of that. It’s a little bit like the position which many people would have held a couple of hundred years ago over slavery. Where lots of people felt morally uneasy about slavery but went along with it because the whole economy of the South depended upon slavery.
David Nibert seeks to expand the field of sociology "...in order to understand how social arrangements create oppressive conditions for both humans and other animals..." He compares speciesism to racism and sexism. Some have suggested that simply fighting speciesism is not enough because intrinsic value of nature can be extended beyond sentient beings, termed the ethic of "libertarian extension. This belief system seeks to apply the principle of individual rights to not only all animals but also objects without a nervous system such as trees, plants, and rocks.
I am a speciesist. Speciesism is not merely plausible; it is essential for right conduct, because those who will not make the morally relevant distinctions among species are almost certain, in consequence, to misapprehend their true obligations.
Jeffrey Alan Gray, British psychologist and a lecturer in experimental psychology at Oxford, similarly wrote that:
I would guess that the view that human beings matter to other human beings more than animals do is, to say the least, widespread. At any rate, I wish to defend speciesism...
A common theme in defending speciesism tend to be the argument that humans "have the right to compete with and exploit other species to preserve and protect the human species."
The central analogy to the civil rights movement and the women’s movement is trivializing and ahistorical. Both of those social movements were initiated and driven by members of the dispossessed and excluded groups themselves, not by benevolent men or white people acting on their behalf. Both movements were built precisely around the idea of reclaiming and reasserting a shared humanity in the face of a society that had deprived it and denied it. No civil rights activist or feminist ever argued, “We’re sentient beings too!” They argued, “We’re fully human too!” Animal liberation doctrine, far from extending this humanist impulse, directly undermines it. -Peter Staudenmaier
Although Camilla Kronqvis sympathizes with Singer’s aims, she does not accept his arguments. She writes "To say that our morality rests on attending to somebody’s pleasure and pain, also seems to be a pretty crude description of what it is to be a moral being." And concludes "I also find it highly unlikely that a polar bear would care for my interests of leading a long, healthy life if it decided to have me for lunch, and I wonder if I would have time to present it with Singer’s arguments when it started to carry out this intention. Singer responds that that fact that animals are not moral agents does not prevent them from being moral patients, just as humans who are not moral agents remain moral patients, so that their ability to be harmed remains the characteristic taken into consideration.
Some more radical opponents of the idea of speciesism believe that animals exist so that humans may make use of them, be it for food, entertainment or other uses. This special status conveys special rights, such as the right to life, and also unique responsibilities, such as stewardship of the environment.
Carl Cohen argued that racism and sexism are wrong because there are no relevant differences between the sexes or races. Between people and animals however, there are significant differences, and they do not qualify for Kantian personhood, and as such have no rights. Animal rights advocates point out that because many humans do not qualify for Kantian personhood, and yet have rights, this cannot be a morally relevant difference.
Objectivists argue that giving more rights to animals means taking rights away from thinking beings who are, unlike animals, capable of creating value. Animal rights advocates respond by pointing out that not all humans are capable of "creating value" by this definition of value, so if "creating value" were the morally relevant characteristic, it would still not track along the lines of species alone. Conversely, any definition of "creating value" that included all humans would include many animals as well.
Some believers in human exceptionalism base the concept in the Abrahamic religions, such as the verse in Genesis 1:26 "And God said, Let us make man in our image, after our likeness: and let them have 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." Animal rights advocates however argue that dominion refers to stewardship and does not demote any right to mistreat other animals. And, still others often point out the overlooking of verses 3:19-21 from Ecclesiastes, which confronts this matter directly. Buddhism, despite its reputation for respect for animals, explicitly accords humans a higher status in the progression of reincarnation. Animals may be reincarnated as humans, but only humans can reach enlightenment. However, Felipe Fernández-Armesto writes that early hunter-gatherer societies such as the Innu and many animist religions have lacked a concept of humanity and have placed non human animals and plants on an equal footing with humans.
Others take a secular approach, such as pointing to evidence of unusual rapid evolution of the human brain and the emergence of "exceptional" aptitudes. As one commentator put it, "Over the course of human history, we have been successful in cultivating our faculties, shaping our development, and impacting upon the wider world in a deliberate fashion, quite distinct from evolutionary processes. Constance K. Perry asserts that the use of 'non-autonomous' animals instead of humans in risky research can be based on solid moral ground and is not necessarily speciesism.