The well-known book by Peter Singer The Liberation of Animals has not only inspired a series of texts defending the rights and interests of animals, but has also provoked a discussion about what humanity is, what meaning can our belonging to the human kind have for us, and whether Singer’ critique of the “human prejudice” is justified. The paper considers two important defenders of “human prejudice”, B. A. O. Williams and C. Diamond, who both claim the concept of human being to be a basic ethical concept. In the first part, we will present Williams’s argument that solidarity and identity with one’s species doesn’t have the structure of a blameworthy privilege similar to sexism and racism. In the second part, we will proceed to Diamond’s conception of human being that is founded in relations and responses towards the other. Just as our treatment of a human being depends on whether we see this person as our fellow, so our treatment of an animal depends on how we see it. In the last part, we will consider Diamond’s illustration of how it is possible to change our perception of an animal and thus to change our treatment of it.