osophical mood. Last month, however, saw a major philosophical event: the publication of Derek Parfit's long-awaited book On What Matters. Until now, Parfit, who is Emeritus Fellow of All Souls College, Oxford, had written only one book, Reasons and Persons, which appeared in 1984, to great acclaim. Parfi

re of this planet in other ways, so that it continues to support intelligent life." Many of us had already reached that conclusion. What we gain from Parfit's work is the possibility of defending these and other moral claims as objective truths. Peter Singer is Professor of Bioethics at Princeton Universi