One man sees a future in which all embryos are genetically programmed in laboratories. Parents would select not only the eye color but the intelligence of their children. Scientists would guide human development away from cancer, depression and perhaps even violence.
Another man looks over this same vision and recoils from a horrifying utopia. The skeptic sees an aristocracy of "enhanced humans" rising up to dominate those who would still conceive babies through sex. The majority might try to purge unpopular traits such as homosexuality from the gene pool.
A vote is expected in the U.S. Senate this spring on a proposed ban on human cloning. Scientists and religious groups have launched lobbying campaigns, including television and radio ads, to argue for or against alternative methods of human reproduction.
The extreme poles of this argument are embodied in two men, Gregory Stock and Francis Fukuyama, who have contrasting experiences and have been waging a debate in books, over the Internet and before audiences.
Stock, 52, is a California medical school professor - a libertarian and technology lover with no children - who has been trying in vitro fertilization to conceive a baby with his 42-year-old wife.
Stock is outraged that conservative, "tyrannical" politicians, many of whom he says lack even rudimentary scientific education, are trying to inject themselves into what he believes should be personal reproductive and medical decisions.
"What kind of a country do we live in when we are talking about banning research that could cure diseases and allow infertile couples to have children?" asks Stock, director of the Program on Medicine, Technology and Society at the University of California, Los Angeles School of Medicine. "Science should not be micromanaged by politicians."
Fukuyama, a 49-year-old father of three who lives in the Washington suburbs, gazes into his children's eyes and is repulsed by the thought that parents might clone or genetically engineer their children.
His voice is heard by the president. A Harvard-trained political scientist and author of the best-selling book The End of History and the Last Man, Fukuyama was asked to serve as one of the 18 members of the President's Council on Bioethics, an advisory panel preparing a report for President Bush to help him decide whether to sign or veto a ban on cloning. Bush has said he favors a ban on reproductive cloning.
"When I think about the idea of actually trying to design your own children, and all of the risks that would entail, I couldn't conceivably be willing to do that," says Fukuyama, since July a professor at the Johns Hopkins School for Advanced International Studies in Washington. "I can see that each child is unique and has his or her own individual purpose in life. I think it would be repulsive if I had a hand in manipulating that uniqueness."
Legislation to ban all cloning has been proposed by Kansas Republican Sen. Sam Brownback. The bill echoes legislation passed by the House last year and prohibitions adopted by Germany, Japan and 22 other nations.
A less strict bill is being proposed by Democratic Sens. Edward M. Kennedy of Massachusetts and Diane Feinstein of California. They want to ban cloning for the creation of babies but would permit so-called "therapeutic cloning," which would allow scientists to clone and then destroy embryos during the process of harvesting their stem cells. These cells are the basic building blocks of life researchers are trying to grow into regenerative tissue that could repair injuries and cure disease.
Other scientists in middle
Stock wants to allow therapeutic cloning, but Fukuyama is against it. Many scientists are put off by the extremity of both positions because they favor an expansion of stem cell research but believe that it would be irresponsible to try cloning people.
Last week's unconfirmed reports that an Italian fertility doctor might have implanted a cloned embryo in a woman's womb lends more urgency to the question of whether governments should intervene. Experts warn that the successes in cloning sheep, cats and other animals do not prove that cloning a healthy human child would work. Many animals born through cloning have unpredictable genetic defects, scientists say.
Although the rhetoric of the cloning debate is often intense, Stock and Fukuyama say they respect each other and have a few things in common. They both have ties to Johns Hopkins - Fukuyama is a professor at the university, and Stock earned his undergraduate and doctoral degrees there during the 1970s.
Both recently began national publicity tours to promote books just published on the biotechnology revolution, Stock's Redesigning Humans and Fukuyama's Our Posthuman Future.