Speciesism

Speciesism involves the assignment of different values, rights, or special consideration to individuals solely on the basis of their species membership. The term is sometimes used by animal rights advocates, who argue that speciesism is a prejudice similar to racism or sexism, in that the treatment of individuals is predicated on group membership and morally irrelevant physical differences. Their claim is that species membership has no moral significance.

Initially it was easy to decide who got rights and who didn't—humans had souls, and animals didn't so we could kill them and eat them with impunity. With the realization that souls don't exist it became necessary to find other ways to differentiate humans from other animals so as to keep humans on top. Various measures have been suggested, including tool use and language. However studies are constantly wearing away at the boundaries between mankind and the "animals" which leads some to suggest that there is really nothing inherently different between mankind and animals and that we are simply part of a continuum. However, speciesism does not necessarily only apply to human supremacism. The term can also refer to the more general idea of assigning different weights to the values of different species. For example, valuing the interests of dogs over the interests of pigs, or valuing the interests of chimpanzees over the interests of cows, or of cows over the interest of.

Equal Consideration of Interests
The concept of speciesism was popularised by the Australian philosopher Peter Singer in his book Animal Liberation (1975). He credited Richard D. Ryder with having coined the term and used it in the title of his book's fifth chapter: "Man's Dominion ... a short history of speciesism", defining it as "a prejudice or attitude of bias in favour of the interests of members of one's own species and against those of members of other species":

"Racists violate the principle of equality by giving greater weight to the interests of members of their own race when there is a clash between their interests and the interests of those of another race. Sexists violate the principle of equality by favouring the interests of their own sex. Similarly, speciesists allow the interests of their own species to override the greater interests of members of other species. The pattern is identical in each case."

It is clear that animals and humans do not always share the same interests - humans often have an interest in being able to vote, owning property, getting an education etc. These interests are not shared by nonhuman animals. However, humans and animals do share some similar interests, such as an interest in food, water, shelter, companionship, freedom of movement, not being killed and avoidance of pain.

Human vs. Non-human Animal Life
It should, however, be noted that it is not always speciesist to favour human interests over animal interests, as sometimes there are indeed morally relevant differences. Anti-speciesism is simply rejecting favouring human interests over animal interests when there are no such differences.

The standard Animal Liberation argument goes:

Therefore, categorically excluding non-humans from ethical consideration is unreasonable. Of course, comparing the values of humans on the basis of cognitive capacities can have very nasty consequences. Indeed, Singer is a eugenicist, maintaining that in some cases, parents should be allowed to kill their disabled babies. Disabled humans generally do not like being compared to animals, nor being considered or argued to be less worthy of life than a healthy dog.

Animal Liberation activists, among others, often ignore disabled people complaining about Singer because of his work on Animal Liberation and overlook his eugenicist beliefs. They rebut this as poisoning the well and a genetic fallacy.

Evolution
Richard Dawkins, the evolutionary biologist, argued against speciesism in The Blind Watchmaker (1986), The Great Ape Project (1993), and The God Delusion (2006), elucidating the connection with evolutionary theory. He compares former racist attitudes and assumptions to their present-day speciesist counterparts. In the chapter "The one true tree of life" in The Blind Watchmaker, he argues that it is not only zoological taxonomy that is saved from awkward ambiguity by the extinction of intermediate forms, but also human ethics and law. Dawkins argues that what he calls the "discontinuous mind" is ubiquitous, dividing the world into units that reflect nothing but our use of language, and animals into discontinuous species:

"The director of a zoo is entitled to 'put down' a chimpanzee that is surplus to requirements, while any suggestion that he might 'put down' a redundant keeper or ticket-seller would be greeted with howls of incredulous outrage. The chimpanzee is the property of the zoo. Humans are nowadays not supposed to be anybody's property, yet the rationale for discriminating against chimpanzees is seldom spelled out, and I doubt if there is a defensible rationale at all. 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 elaborated in a discussion with Singer at the Center for Inquiry in 2007, when asked whether he continues to eat meat: "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." . He also stated in an interview in 2013 that he believes that in 100 to 200 years from today, humans will look back on how we treat animals today in a similar vein to how we now look back on our ancestors who kept slaves." Using slavery as an excuse to promote your agenda is of course messed up and racist. Many black people object that this comparsion as dehumanizing, some have said the comparison was one of the reasons why black people are reluctant to join the animal rights movement.