ABSTRACT
A liberation movement demands an expansion of the moral horizons and an extension or reinterpretation of the basic moral principle of equality. There are important differences between humans and other animals, and these differences must give rise to some differences in the rights that each have. Recognizing this obvious fact, however, is no barrier to the case for extending the basic principle of equality to nonhuman animals. The differences that exist between men and women are equally undeniable, and the supporters of Women's Liberation are aware that these differences may give rise to different rights. Many feminists hold that women have the right to an abortion on request. Equality is a moral ideal, not a simple assertion of fact. 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 animals.
