eon R. Kass's ''Life, Liberty and the Defense of Dignity'' is hardly a novel or a book of the sort nowadays called ''literary nonfiction.'' Quite the opposite: it is a demanding philosophical discourse addressing a series of complex ethical and biomedical issues. And yet, as with virtually all of Kass's previous writing, we begin to miss the reassuring rhythms of his guiding voice as soon as we've read the last sentence. For Kass illuminates the human condition, fostering reverence for the multifarious aspects of our shared humanity by viewing the most technological of bioethical concerns through the lenses of the morality, love and creativity that characterize our species at its best.
But reader beware, as you admire the elegance of Kass's writing, the sweep of his erudition and the appeal of his narrative, lest you forget that you are in the company of perhaps the most conservative of bioethicists -- and certainly the most persuasive of the polemicists declaiming against the unquestioning acceptance of the technological imperative currently gripping the imagination of an enthusiastic American public. Kass leaves little room for compromise or adjustment. Under the spell of his luminescent writing, one is tempted to abandon long-held assumptions about the inviolability and freedom of the scientific enterprise. His is a voice that properly deserves attention, but always with the caveat of its seductiveness.
Kass is that rarest of bioethicists -- one who has had rigorous training in basic science, with both an M.D. (from the University of Chicago) and a doctorate in biochemistry (from Harvard). It was during his days as a newly minted researcher in bacterial physiology at the National Institutes of Health in the late 1960's that he began to turn his determined attention to the need for formalized study of the problems arising from the exciting revolution in biology then in its early stages. He and others gathered together to found the Hastings Center, the first American bioethics think tank. Since then, he has established himself among the most respected authorities in the field.
And yet, when President Bush appointed him last year to chair the Council on Bioethics with the charge of recommending federal policy on cloning and stem-cell research, there were grumblings among his colleagues. By choosing Kass, many ethicists and scientists said, the president was assuring himself that the council's final report would be in accord with his own position that all human cloning should be forbidden -- not only the cloning of an entire human being (called ''reproductive cloning'') but also cloning to provide early-stage embryonic stem cells for research that might yield tissues for the treatment of disease.
Kass's views are clearly expressed in the early chapters of ''Life, Liberty and the Defense of Dignity,'' in the form of concern that once scientists have begun to produce cloned embryos in laboratories, ''it would be virtually impossible to control what was done with them.'' In a lucid exposition of the slippery-slope argument, articulated far more persuasively than I have ever encountered it except in Kass's own writings, he argues that ''once embryonic clones are produced in laboratories the eugenic revolution will have begun. And we shall have lost our best chance to do anything about it.'' In other words, all cloning for medical research should be stopped.
In opposing reproductive cloning, Kass is in step with the majority of Americans. But he is in distinct disagreement with them and with almost all biomedical scientists in his opposition to cloning for research and therapy. The specter of the slippery slope, however, is not his main argument. His objections arise from considerations far more fundamental and profound than concern over the likelihood of out-of-control technology. He urges his readers to consider the very nature of what it means to be human. While eschewing theological debate about the beginning of life, he argues for an undeniable secular reality: ''The blastocyst,'' the five-day-old ball of some 64 to 200 cells on which the research would be done, ''is not nothing; it is at least potential humanity, and as such it elicits, or ought to elicit, our feelings of awe and respect. In the blastocyst, even in the zygote,'' the union of sperm and egg, before any cell division has taken place, ''we face a mysterious and awesome power, a power governed by an immanent plan that may produce an indisputably and fully human being. It deserves our respect not because it has rights or claims or sentience (which it does not have at this stage), but because of what it is, now and prospectively.'' To Kass, the blastocyst is already a fragment of humanity.
What the blastocyst is ''prospectively'' is a human being, with the potential for a distinct identity, dignity, love, sexuality, familial bonds, a spiritual nature and the capacity to change the world for a few or for many of us; it is not merely a collection of cells. Notwithstanding Kass's denial, this means that the blastocyst does in fact have a powerful claim on influencing any decisions made about its production and its future. But for Kass, the claim of the blastocyst not to be destroyed outweighs the claims of men, women and children already grown to independent life, who suffer from diseases potentially remediable by the respectful study and use of embryonic tissue. Other than those whose viewpoints are forged by theology, not many members of our present-day society will agree with him. Paradoxically, one can argue, it is precisely because of the humanity and dignity of the sick and disabled that research on blastocysts should be encouraged. The four-year moratorium recommended by Kass's committee can be seen as flying in the face of the principles he so eloquently espouses. A reader's mind is lured by the learned assurance in which Kass couches his argument, until its implications are considered.
Kass is on far firmer ground when dealing with other bioethical conundrums. An example is his opposition to genetic engineering for the purpose of enhancement -- the improvement of individual characteristics -- rather than merely to treat disease. He correctly points out that ''the road we are traveling leads all the way to the world of designer babies -- reached not by dictatorial fiat, but by the march of benevolent humanitarianism.'' After all, when genetics laboratories make straighter noses and longer legs available, what parent with the means to do so would willingly deprive his or her child of the possibility, especially when the newly implanted gene will be passed down to all future generations? ''Increasing control over the product can only be purchased by the increasing depersonalization of the entire process,'' Kass says. Procreation, he argues, will become manufacture; the consequences of the so-called regenerative medicine are ignored at the peril of our humanity, be they such obvious folly as the cosmetic improvement of the breed or the far more complex possibilities inherent in cloning for therapeutic purposes. As for the rapidly expanding research that promises to extend the human life span by a hundred or more years, there is no end to the complexities either of its appeal or its caveats -- or of its effect on the meaning of being human.
Genetic engineering, stem-cell therapy, reproductive cloning, life-extending chromosomal manipulations -- these are all technologies of high promise and no fulfillment as yet. It will be years or perhaps decades before any of them becomes reality, if ever. But certain of the ethical decisions to which Kass addresses himself in this provocative book must be made at the bedside every day, and they are no less controversial than those still hovering in the laboratory. These concern the right-to-die movement, physician-assisted suicide and the sale of organs for transplant. On the basis of their distortion of our common humanity, he rejects them all.
Kass has written an important book. Whether or not one agrees with the basic elements of his thesis, it is impossible to ignore the brilliance or the conviction with which he supports it. Some, persuaded by the sheer forcefulness of his argument, will join him in absoluteness. But most will read the necessities of our humanness differently, and recognize the need for flexibility. Either way, there can be no clearer exposition of the moral complexities of 21st-century biotechnology than has been provided by Leon Kass's intellectual depth and graceful style. As with the work of a great novelist, nostalgia sets in at the ending of a well-told tale. Beware.
Sherwin B. Nuland's ''Lost in America'' will be published in January. He is a clinical professor of surgery at Yale University and the author of ''How We Die.''
