In his article All Animals Are Equal, philosopher Peter Singer claims an argument for animal liberation. He concludes that other species deserve rights and interests as equal as human beings. He clarifies that his definition of “sentience” refers to the capacity of creatures to experience things like suffering and enjoyment or happiness. He suggests that the capable of sentience is the only plausible criterion of moral importance to makes his conclusion in a meaningful way (Singer, p.179). In this paper, I argue that the capability of sentience for beings is not the only criterion of moral importance to take in to account when advocate equal consideration of interests for all animals. The argument that I wish to focus on in my paper is the following: 1.If beings are capable of sentience, then they deserve to have interests. 2.Human beings and many non-human animals are capable of sentience. 3.Therefore, human beings and many non-human animals should have interests. 4.If beings cannot capable of sentience, then it would be nonsense to concern their interests. 5.The criterion of sentience does hold significance over any other criteria which human beings may care to choose as an indicator to determine whether a creature deserve to have equal interests as human beings have . 6.Suffering is immoral, then it should avoid to happen.
7.If non-human animals suffering, then there can be no moral justification for refusing to take that suffering into account and given them the same weight as the interests human beings have in avoiding suffering. 8.Thus, the capability of sentience is the only defensible boundary of concern for extends to non-human creatures the same equality of consideration of interests that extend to human beings have in avoiding suffering.