According to Singer, it is not directly wrong to kill 'non-self-conscious beings', such as lower animals, human foetuses and newborn infants, provided that any consequent loss of happiness is made good by the creation of new sentient life. In contrast, normal adult humans, being 'self-conscious', generally have a strong preference for going on living, the flouting of which cannot, Singer argues, be morally counterbalanced by creating new, equally happy individuals. Singer's case might be reinforced by taking account, not only of (...) the preference for continued life itself, but also of other preferences for whose satisfaction continued life is essential. It proves difficult, however, to find a formulation of 'preference utilitarianism' which, while lacking other obviously unacceptable consequences, supports Singer's 'non-replaceability principle'. Also, Singer's position fails adequately to accommodate our conviction that the lives of human beings are, in general, more valuable than those of other animals. Finally, his thesis that lower animals (let alone human infants) are replaceable, has decidely counterintuitive implications. (shrink)