Peter Singer, the originator of anti-speciesism, claims to have developed a logical approach to the animal situation based on Jeremy Bentham's utilitarian moral theory, which was formed in the 18th century. Utilitarianism is a philosophical concept that promotes a duty - based approach to morality. Each activity must be assessed in terms of its impact on the overall well-being of the community.
Speciesism is defined as discrimination based only on species membership. Speciesism is when you eat a hot dog while petting a cat. It entails using animal-tested cosmetics while your dog is being groomed.
Anti-speciesism is recognizing that dogs and pigs have the same desire to be free of pain, and not eating one while admiring the other. Anti-speciesism is the belief that all suffering is equal, regardless of the individual's species membership.
Anti-speciesism does not imply that carrots, flies, pigs, and people should all be treated the same (even though, yes, they all belong to different biological species). Anti-speciesism merely asks that the same interests, or interests of similar strength, be taken into consideration to the same amount.