ABSTRACT
In arguing that animals do have rights—and in particular that they have a right to liberty—one may use the following method. First one may select for discussion a right which they are confident that humans do have. Then they can ask whether there is a relevant difference between humans and animals which would justify us in denying that right to animals while at the same time granting it to humans. If not, then the right in question is a right possessed by animals as well as by humans. The right to liberty has been counted among the most fundamental human rights in all the great liberal manifestos of modern history. The right to liberty—the right to be free of external constraints on one's actions—may then be seen as derived from a more basic right not to have one's interests needlessly harmed. Animals that suffer in captivity have an interest in being free, and so a prima facie right to liberty.
