AT A GATHERING of the World Economic Forum in Davos several years ago, Nobel laureate James Watson, whose work on DNA did much to advance the biotechnology revolution, expressed optimism that human society would never clone human beings because of the moral implications.

There would be no "boys from Brazil," he said. The Boys From Brazil was the title of a book published in the early 1970s as a science-fiction thriller by Ira Levin. In the book, and in a subsequent movie that starred Gregory Peck, Sir Laurence Olivier and James Mason, a Nazi doctor deep in the Amazon jungle, Josef Mengele, plans to breed dozens of Adolf Hitlers, cloned from the original, to achieve Nazi world domination.

The book succeeded in raising fears that scientific knowledge could be employed for evil purposes or, more benignly, to breed, say, subhumans with limited intelligence to perform menial chores.

In today's world, this remains science fiction. We simply don't know how to do such things, even if we wanted to. But the opportunistic announcement by a small U.S. company, Advanced Cell Technology Inc., that it had cloned human embryos has raised anew societal concerns over the power of humans to alter life forms, and precipitated panic calls to ban all such research.

Prime Minister Jean Chrétien, for example, has promised all such activity will be banned in Canada.

Yet it's important to gain a better understanding of what is at stake, and to distinguish science from science fiction.

In many respects, we have been cloning or altering life forms for many years -- altering plant life and many forms of insect and animal life. So society is faced with deciding why it is all right to breed new forms of cattle or dogs, but not all right to tamper with humans.

This raises a fundamental divide between theologians, who see human beings as distinct moral creatures quite different from any other species of life, and scientists, who see humans as just one of many forms of biological existence. Indeed, perhaps the greatest change in understanding over the past 50 to 100 years is the recognition of the biological link between humans and other forms of life. The fact that we have almost all the same genes as an earthworm underlines this point. This debate has the most profound implications for society.

There is another reason for public concern and that is a sense of helplessness on the part of ordinary citizens who feel they lack the knowledge that scientists possess and fear that scientists are doing things in secret that they do not have the right to do on their own. This divide between ordinary citizens and scientists has to be bridged.

Then there is a justifiable concern that companies such as Advanced Cell Technology want to gain powerful patents that would allow them to control what should be public goods, thereby gaining the potential to earn billions of dollars in the process.

Yet, there is another side to all of this, which is the potential to develop new medical techniques that could improve the lives of millions of people who suffer from ailments such as diabetes, Parkinson's disease, heart diseases and Alzheimer's. Should people be denied the opportunity to live better lives?

In looking at how to address conflicting concerns, we need to distinguish between the use of cloning to reproduce human beings and the use of cloning to produce embryos to gain stem cells to cure disease.

It would reassure many if the reproductive cloning of complete humans, or genetic intervention to design children, was banned.

But even if countries such as Canada and the United States did so, this would not prevent maverick scientists from establishing clinics in other parts of the world where our concerns are not shared.

The more immediate issue is the production of human embryos to produce stem cells that can be used to repair damaged tissue from heart disease or to deal with diseases such as diabetes or Parkinson's. The British have opted for a process that permits therapeutic cloning under regulated conditions, though the courts have forced the government to rewrite the legislation. For its part, the Bush administration wants to ban research of any kind.

Before rushing to emulate the United States, Canada should look more carefully at the reasons why Britain decided against banning such research.

Since the medical gains are potentially so great, on balance it would make more sense to permit and regulate such research if it means that millions of people would be able to live healthier and fuller lives.