Heta Häyry, Avebury Series in Philosophy, Ashgate, Aldershot, 1998, vi+102 pages, £29.95.

This is a short but very interesting book, which repays study. It is essentially a defence and an application to medical ethics of the principle of liberty (page 12), that “the liberty …of competent, well-informed, free agents must be …maximally protected in matters which concern only or mainly themselves”. Adoption of this Millian principle, which is argued for in the introduction, along with the adoption of principles of equality (that the needs and interests of all should be taken into account) and of responsibility for the welfare of one's fellow beings, raises, it may be said, three questions: who is a person (and therefore to be taken into account); when is a person sufficiently competent, and when do people have to sacrifice some liberty to help or protect the welfare of others? Chapter 1 tackles the first of these questions, following the defence of the principle of liberty in the introduction; chapters two to four deal with issues raised by the second question—whether …