The arguments in favor of speciesism are based mainly on religious beliefs, anthropocentric philosophical conceptions and the concept of preference for its species.
Some religious traditions claim that animals were created for human use, and that humans are special creatures. For example, the Abrahamic religions teach that man was created in the image and likeness of God, unlike animals that were created to serve man.
“Then God said: Let us make man in our image, according to our likeness, and let him rule over the fishes of the sea, the birds of the sky, the cattle, all the earth, and all the reptiles that crawl on the ground.”
– Genesis 1:26
Although Buddhism recognizes for animals a moral status of sentient beings and although Buddha has advocated vegetarianism, Buddhism is a hierarchy of beings, some more advanced than others in the cycle of reincarnations. Animals can be reincarnated as humans, humans can be demoted to animals in their next life if they misbehave, and only humans can directly reach enlightenment (animals must first reincarnate as humans).
We find this conception of progression in reincarnations in Hinduism. Some Hindus are vegetarians, with deep respect for cows in particular (representing the earth/mother, the central figure).
One of the philosophical defenses of speciesism is anthropocentrism. It is based on the idea that only humans possess certain mental abilities considered as superior such as reason, language, autonomy, intelligence, etc. Traditionally, since Aristotle, it is the reason, the self-awareness and the capacity to act morally that are considered exclusive to the human species.
The philosopher Carl Cohen wrote that racism and sexism are unfair because there is no relevant difference between the sexes or between races, while there are significant differences between species. Animals are not people according to Kant’s definition, so they have no rights. He also believes that speciesism is necessary to act morally:
“Specism is not simply plausible, it is essential to right conduct, because those who do not see morally relevant differences between species are almost sure, therefore, to misunderstand their true obligations.”
Peter Staudenmaier, Associate Professor of History at Marquette University, wrote:
“The analogy with the civil rights movement and the feminist movement is trivializing and ahistorical. These two social movements were initiated and led by the members of the discriminated groups themselves, not by benevolent men and whites acting in the name of the discriminated. These two movements were built on the idea of claiming and reaffirming a common humanity in the face of a society that had withdrawn and denied them. No activist for civil rights or women’s rights argued that “We are sentient beings too!”. They argued, “We are fully human too!”. Now, the animal liberation movement does not take up this humanistic argument, it directly criticizes it.”
The preference for the group
Several authors have stated that humans have a duty of preference towards their species and that this duty founded speciesism.
A theoretical foundation for group preference has been proposed by Jean-Pierre Dupuy, which makes it flow from a logic of solidarity allowing each human to increase the probability of his own survival. Historically, this solidarity was first established at the level of restricted human groups, and could exclude other groups whose rights were ignored; then the sphere of solidarity gradually spread to the whole human species. Humans have a great interest in defending a moral system in which life and certain human rights are sacred and must be preserved absolutely. Jean-Pierre Dupuy calls this system “self-transcendent” because it would be a human construction now perceived as absolute and above humans.