||It is a welcome development when academic Philosophy; starts to concern itself with practical issues, in such a way as to influence people's lives. Recently this has happened with one moral issue in particular-but unfortunately it is the wrong issue, and people's actions have been influenced in the wrong way. The issue is that of the moral status and treatment of animals. A number of philosophers have argued for what they call 'animal liberation', comparing it directly with egalitarian causes such as women's liberation and racial equality and suggesting that, if racism and sexism are rationally indefensible, so is 'speciesism'. If one ought to give equal consideration to the interests of all human beings, then, so they claim, one must on the same grounds and in the same way recognize that 'all animals are equal', be they human or non-human. We believe that this assimilation of 'animal liberation' to human liberation movements is mistaken. We focus our discussion on what we take to be the most persuasive defence of 'animal liberation', that put forward by Peter Singer.1 The essence of Singer's case is this: traditional attempts to justify equal consideration for the interests of all human beings, but not equivalent consideration for the interests of non-human animals, have consisted in identifying some property-such as the possession of rationality, or language, or intelligence, or moral capacities-supposed to be characteristic of human beings and to distinguish them from all other species. But any property we might select either will not be possessed by all human beings, and so will involve us in unacceptable moral conclusions about how to treat, for example, very young children or human imbeciles; or, if it is possessed by all human beings, will be possessed by some non-human animals as well.