For this collection, R. M. Hare has selected the best of his writings on medical ethics and related topics. Its chief theoretical interest lies in its synthesis between utilitarian and Kantian ethics, which are shown to have the same practical consequences. The main practical thesis in the book is that we can harm possible people by preventing them from becoming actual people. This thesis, if understood and accepted, would radically alter the terms of the public debate about embryo experimentation and population policy, and (perhaps surprisingly) support a fairly liberal view on abortion. There are also general introductions to medical and psychiatric ethics, and essays on the concept of health, the morality of experimentation on children, health care policy, free will, and vegetarianism.