It is perhaps the first branch of philosophy to grow to full strength in the age of the opinion poll. Now the Human Fertilisation and Embryology Authority has decided to put its latest consultation document on to the Internet, as well as publishing it in print, in order to check what the public thinks about what is called "pre-implantation genetic diagnosis". People are being asked, in effect, to help decide which diseases are serious enough to warrant the destruction of a human embryo. (The websites are www.hfea.gov.uk and www.open.gov. uk/doh/genetics)
The specialists and pressure groups have already got in on the philosophical act. Pro-lifers have denounced the new technique as "meddling in human evolution". Professor Robert Winston, head of the in vitro fertilisation clinic at Hammersmith Hospital, has denied that this could be the first step on a slippery slope towards quality control of children.
Of course, in the classic Mandy Rice-Davies phrase: "He would, wouldn't he?" In fairness, it must be said that the pro-life people are right to fret about what may be about to come next. On this terrain, so far, no frontiers have remained uncrossed. It is also worth remembering that Professor Winston - he is now a Labour life peer - was himself sceptical about, and even hostile to, the attempt to create "test-tube babies" until Robert Edwards and Patrick Steptoe, after a long struggle, finally showed that it could be done.
Now, you could say that we meddle in human evolution all the time. So do all species. Without meddling, in fact, no evolution could take place at all. How, as Kipling asked, did the elephant get his trunk, or the giraffe his spots; or - as the recent BBC TV series marvelled - how did some dinosaurs manage to survive to the present day by reinventing themselves as birds? Whether we line up with early Lamarck (who believed in the inheritance of acquired characteristics) or late Darwin (selection of the most useful random mutations) or omnipresent Herbert Spencer (who invented the phrase, "survival of the fittest"), we can all agree that nothing, in evolution, has ever stood still for long.
But the meddling has unarguably become more precise. A GM tomato is somehow not quite the same thing as a tomato re-engineered by wandering along the greenhouse aisle with a rabbit's tail as artificial pollinator. But exactly why isn't it the same? Are we just arguing about time? Does faster mean worse? Or does that line you up with all those who panicked when the steam locomotive, for the first time in evolutionary history, produced a means of travel that went faster than even a horse could go?
The current argument is, on the face of it, about something very precise indeed. So far, it relates only to babies produced by IVF techniques. Cells are taken from embryos a few days after fertilisation. Only an embryo without genetic abnormality is then implanted in the womb. This system of pre-selection has so far been used - in Britain, at least - only to screen out specific, highly disabling risks, such as cystic fibrosis and muscular dystrophy. (Nor has it been used to screen for anything other than what tests during a normal pregnancy have long been able to throw up.)
The Human Fertilisation and Embryology Authority does not want anyone crossing the boundary into screening embryos for sex or intelligence. But, as this example shows, bio-ethics rapidly unscrolls into almost every part of life - and death. The debate is at its fiercest in the United States, where the cheerful claim by the Declaration of Independence that life, liberty and the pursuit of happiness are "unalienable rights" has left open the question, for example, of whether a prospective parent's right to those attributes should override a prospective child's. This year, Congress has even been refusing to release money that the United States owed to the United Nations unless funds were cut off for American family planning organisations that promote abortion in the Third World.
Notoriously, American abortion clinics have been bombed and doctors murdered. Among its other purposes, the embryology authority was set up in Britain in order to try to damp down any such tendencies and keep the debate under elite control. The new consultation shows that this may not be permanently possible - though access to the Internet is still socially skewed; it is a long way from being a mass medium.
Peter Singer is the philosopher whose book, Animal Liberation (first published in 1975), launched that particular bio-ethical movement in its present form. The book has sold half a million copies. He has just moved to America, having been appointed by Princeton University as its first professor of bio-ethics. He is based in the university's Centre for Human Values and Philosophy.
He is one of those men who write fiercely but speak gently, as I found when I talked to him at Princeton soon after he took up his new post. These days he is preoccupied with "life and death decisions". He considers the power of science, especially in matters of genetics, "rather scary". But he has found himself caught in the crossfire of debate in the United States because of his tolerant stance on euthanasia (and those who believe that even an embryo has life would say that even pre-implantation screening means a kind of early-day euthanasia). A nine-page article about Singer in The New Yorker this autumn was headed "The Dangerous Philosopher."
He is, he says, "less troubled by killing than by suffering". He has called man's domination over other animals a "speciesist" abomination that can be compared to the pain that "resulted from the centuries of tyranny by white humans over black humans". What matters, to Singer, is not whether an animal can reason or talk, but whether it can suffer. He has now gone on to argue that, if a severely disabled human infant faces a life of nothing but suffering, that child - or, presumably, that foetus - would be better off dead. Princeton was unprepared for the protests that Singer's appointment brought. The university is reported to have taken elaborate measures to ensure his safety. Not many recent philosophers, since the Soviet Union collapsed, have had to consider the dangers to their own lives from their ethical arguments.
Bio-ethics is not, and cannot be, just an issue for the lecture room or the seminar. When I was talking to Singer, a bright leaf - like an East Coast tourist advertisement for the fall - fluttered in through the half-open window. "It's good to be in touch with Nature like this," he said, with a wry smile. But "what is Nature?" a present-day Pilate might ask. One thing is certain: none of us can wash our hands of the search for an answer.
The writer is Senior Fellow of the Institute of Community StudiesReuse content