According to his theory, when value is given to all other humans regardless of their mental and rational abilities then the same value should be ascribed to the non-human animals as well. His arguments are based on the views of Immanuel Kant that all animals have moral rights but he criticizes Kant’s belief that only rational beings are subjected to respect. Regan rejects this view and argues that humans gain the value and respect regardless of their rationality as with infants and those who are mentally instable thus non-human animals are also subjected to the same value and respect regardless of their rationality. Since all human and non-human animals are subjects-of-a-life, life is the only attribute which would subject to value. Thus every being that is subject-of-a-life must be treated with respect and must be given moral rights (Regan, 2004).
On the other hand, utilitarianism is a theory which proposes that any action will be morally right only when it benefits and provides good to a large number of people. According to this theory, what’s right is determined by the value of pleasure or pain that it causes to other people. If an action causes pleasure to most of the people then it is considered as morally right while if it causes pain and suffering for the people, it will be considered morally wrong. Utilitarianism is often used to justify animal rights as their pain and pleasure is also counted for actions that are morally right or wrong (Brooman, 1997).
Utilitarian theorists believe that biologically it is justified that non-human animals are sentient and biologically they are able to feel pain and pleasure. This is justified also practically as many people have experienced such feelings in animals, especially cats and dogs. There is a lot of evidence that non-human animals are sentient and they feel