In recent years, society has witnessed an explosion of medical and biotechnological advances. Medical procedures that were innovative only a few decades ago—such as organ transplants and in-vitro fertilization—now seem ordinary and commonplace. More recently, scientists have been making significant discoveries in areas that once were relegated to the world of science fiction, including cloning and genetic engineering.

However, many of these biomedical advances raise serious ethical questions. For example, successes in cloning animals have sparked such controversy over the imminent possibility of cloning humans that the U.S. government has placed a moratorium on federally funded research into human cloning. In ordering the ban, President Bill Clinton asserted, “Any discovery that touches upon human creation is not simply a matter of scientific inquiry. It is a matter of morality and spirituality as well.”

Opponents of...