It is not too surprising that her book should take a stand against the fashion for signing up moral philosophers to advise on the dilemmas thrown up by biomedical advances. From the technology of in vitro fertilisation, through to genetic screening for inherited diseases, scientists are turning to a new breed - the 'bioethicists' - to find the way through a moral maze.
There is certainly money in it. The American Human Genome Project - the US national programme to tease out and examine all the 100,000 genes which make up the human blueprint - has put aside some 3 to 5 per cent of its funds to study the social, ethical and legal consequences of the scientist's work. This makes the Human Genome Project the most generously funded philosophy research programme in the world. But Dr Maclean is worried that scientists and doctors may believe that there is a single right answer in questions of morality and ethics. Perhaps, she fears, they will carry over the mind-set of science, which deals, as the late Sir Peter Medawar memorably remarked, only in the Art of the Soluble. Dr Maclean believes, however, that moral philosophers have no particular moral authority, and that the project of coming up with one rational answer to ethical questions is inherently flawed.
Her book is a relentless and unflinching critique of the dominant ethical viewpoint of our times: utilitarianism. One of the most seductive things about utilitarianism, especially to those with some scientific training, is that it seems to offer a moral calculus - a method of weighing conflicting moral demands and arriving at a rational outcome.
But Dr Maclean's message is a variant on the concept first popularised by the computer industry: gigo - garbage in, garbage out. She exposes the moral values which underlie the utilitarian calculus (as unexamined assumptions) and shows that the apparently objective moral conclusions merely reflect the initial assumptions.
Her criticisms of the work of John Harris, professor of applied philosophy at Manchester University, are particularly pungent. Some years ago Professor Harris famously argued for a controversial way of dealing with the shortage of transplant organs for donation. If two people required organ transplants then it was perfectly moral, professor Harris argued, to select a suitable living 'donor' at random, kill this person and extract his or her organs for the benefit of the two people who would otherwise have died.
It is virtually impossible to refute this proposition from a utilitarian viewpoint. There is not space here to rehearse Dr Maclean's discussion except to repeat the fundamental point that to kill a person in this way would be murder, and murder is immoral.
Similarly, Professor Harris has reasoned that the lives of new-born infants have no moral value, that their lives are at our disposal, and that infanticide is not immoral. Dr Maclean points out that this conclusion is a consequence of Professor Harris's starting point, which was to answer the question: why do we value the lives of adult human beings such that murder is wrong? Had he started with the proposition that people value their babies' lives more highly than their own, then he might have come to a different conclusion.
Her second point is simply stated: we do not, as it happens, treat babies as if their lives were at our disposal. 'Bioethicists demand for what reason we do so, but there is no reason - or to put the same point differently, their being babies is the reason, all the reason in the world.'
There's iron integrity for you.