Though Peter Singer focuses almost entirely on the concepts of “speciesism” and the Animal Liberation movement in the book, his arguments have an underlying ideology that surrounds the ideas of difference and equality. While these concepts may initially appear to be each other’s antithesis, Singer argues that this is not necessarily the case. Singer first connects egalitarianism with difference when he dismantles the concept of equality. In doing so, he strives to prove the scientific impossibility of identical sameness. Though humans might have differing traits like gender, race, or hair color, Singer asserts that the ethical and moral argument behind equality is based not on the literal uniformity of the human race, but rather on the fair and equal treatment that all humans deserve. This is most evident when Singer writes, “The principle of the equality of human beings is not a description of an alleged actual equality among humans: it is a prescription of how we should treat human beings” (27). Singer thus establishes that equality is not built upon uniformity, but in spite of difference.

Singer uses this connection between difference and equality to persuade readers that animals are just as deserving of rights as humans are.