Richard Ryder wrote:
"In as much as both "race" and "species" are vague terms used in the classification of living creatures according, largely, to physical appearance, an analogy can be made between them. Discrimination on grounds of race, although most universally condoned two centuries ago, is now widely condemned. Similarly, it may come to pass that enlightened minds may one day abhor "speciesism" as much as they now detest "racism." The illogicality in both forms of prejudice is of an identical sort. If it is accepted as morally wrong to deliberately inflict suffering upon innocent human creatures, then it is only logical to also regard it as wrong to inflict suffering on innocent individuals of other species. ... The time has come to act upon this logic."
But this extends to differences between nonhuman animal species too – hence, when we demonstrate concern for dogs but not cows that too is speciesism. The way we talk about animals that do not fall into our moral sphere – as "it"; as generic categories, e.g., "cattle" – serves to underscore this. Discussed as commodities, and in economic terms, they become "things" not individuals with needs, wants, histories, and lives. And this allows us to kill, maim, execute, and eat them at will[ii].