In this article I will present the implications of the Idea of equality in Pratical Ethics and Ethical Life by Peter Singer, edited in Portuguese, under the perspective of the criticism made by Richard J. Arneson in What, if anything, washes all humans morally equal? Singer proposes that the equality between human and non-humans beings has its base based on the Principle of Equal Consideration of Similar Interests. Arneson, on his turn, analyzes the ideas of Singer and affirms to find what he calls Â“SingerÂ´s problemÂ”. According to his understanding, Singer re-introduces the elitism that he claims to reject. Arneson has given Singer a wrong interpretation. That is what I will try to demonstrate in this paper.