Peter Singer occupies a distinguished position at the Centre for Human Values at Princeton University and is frequently described as the most influential of living philosophers. The front cover of this new selection of his writings couples him with Bertrand Russell and, in some respects, the comparison is sensible. Both philosophers have written clearly and simply on issues that are of interest not only to specialists. They have attracted a wide reading public and achieved the kind of celebrity and notoriety rarely associated with philosophers. Both have been activists – Russell mainly in the cause of pacifism and nuclear disarmament, Singer in the cause of animal liberation and the preservation of the environment – and both have stood for parliament. Each has been the object of energetic campaigns to have major academic appointments in America rescinded, as well as of public protests and demonstrations, threats, violence, and vilification. Of course, things have been worse for philosophers: they have been burned, shot, and hanged. But in this century, anyway, the more peremptory measures were usually remedies for their extracurricular activities, not for their teaching. So the animus against Russell and Singer has been unusual in focussing less on their political activism than on the expression of their moral views: in Russell’s case, principally the advocacy of a more casual attitude to free love, and in Singer’s, principally a more casual attitude to killing people.