Dear Professors Lee and George,
Thank you for responding to my letter, which took issue with points raised in your earlier NRO review of my book Challenging Nature. In your response, you continue to insist absolutely — as you have in numerous articles published on this topic — that a human embryo is a human being, while other clumps of human cells are something entirely different. Rather than continuing to debate this claim in prose, it is useful to take a more visual approach, as illustrated by comparing the two pictures below. Both show color-enhanced scanning electron micrographs of clumps of human cells. But before they were frozen for microscopy, one clump was a normal embryo, while the other was a bunch of embryonic stem cells. According to your logic, one clump was a human being, while the other was just a confined group of proteins, DNA, and other molecules. So tell me, Which one is which?
Perhaps you can’t tell the difference by external appearance alone (I certainly can’t). But even if you could look inside with the finest microscope, it almost certainly wouldn’t help because there is almost certainly no molecule, or combination of molecules, whose presence or absence distinguishes all human embryos from embryonic stem cells. At this point, you may retreat to your previous claim that only the real human embryo has “the epigenetic primordia for a functioning brain and nervous system.” I haven’t a clue what the term “epigenetic primordia” means since it has not been used (as far as I know) by any scientist in any of the hundreds of thousands of basic biological research articles published over the last decade.
I know this little exercise won’t change your mind; I present it simply for the benefit of more open-minded NRO readers. Indeed, it is pointless to debate scientific details when even simple words like “life” and “death” are interpreted by you in ways that are foreign to most practicing biologists. So instead, I would like to put to the test your ‘argument from authority’ claim, which holds that the embryo-is-a-human-being proposition “is a fact confirmed by contemporary embryology and attested to by the standard works in the field.” In fact, none of the standard texts you’ve quoted — or any other prominent biology textbook used at major nonsectarian universities — actually states that an “embryo” is a “human being?” (It won’t do to pretend that biologists use the term “human life” as a standard synonym for “human being.” Human cells growing and dividing indefinitely in petri dishes are fully alive — in biological terms — and fully human in their constituent parts, and yet you yourselves do not consider them to be human beings.)
Furthermore, if the embryo-is-a-human-being proposition really is “confirmed by contemporary embryology,” you might expect at least one of the 52 active professors in the two biology departments at the esteemed university where Professor George and I teach to acknowledge this supposedly confirmed “fact.” I challenge Professor George to identify one — just one — Princeton biology professor who shares this viewpoint. (As an incentive, if you can come up with one name, I will buy you both a case of wine from the same vineyard that produced the delightful bottle I shared with Professor George at a pleasant dinner some years ago.)
If your search for like-minded Princeton biologists comes up empty- handed, you might argue that the liberal or libertarian milieu of Ivy League science faculties discourages professors from expressing any truly-held conservative views. But, in fact, many unabashed, culturally conservative academics simply don’t agree with you either. One who takes exception is University of Chicago professor Leon Kass, the former chairman of President Bush’s Council on Bioethics, on which Professor George also sits. Kass has written, “I myself would agree that a blastocyst [an embryo that is 4 to 9 days post- fertilization] is not, in a full sense, a human being.” (Toward a More Natural Science, p.104). Not only is Professor Kass an accomplished scholar in the area of bioethics, he also holds both a medical degree and a Harvard Ph.D. in biochemistry. I assume, Professor George, that you’ve had many chances to persuade Professor Kass with your “careful argumentation and the presentation of the relevant biological facts,” and (as far as I can tell), you haven’t succeeded. Indeed, from my admittedly subjective point of view, it seems that most academic biologists, most nonsectarian bioethicists, most physicians, and most university-educated conservatives (forget about liberals and libertarians) don’t agree with you. So what gives. Are they all stupid, ignorant, or disingenuous?
As I stated in my previous letter, there is nothing — no fact or concept — that will ever make you budge from your belief in the unassailable truth of the view that an embryo is a human being. It is this form of absolutism that led me to brand you as fundamentalists, mocked in the title of your original book review. However, since I was not raised or educated in a strictly religious tradition, you could argue that I don’t really understand the difference between fundamentalists and non-fundamentalists. But there’s no need to take my word for it because the self-described practicing-Catholic and conservative pundit Andrew Sullivan reaches exactly the same conclusion about Professor George in his hard-hitting new book, The Conservative Soul. According to Sullivan, George and others who hold his extreme views are fundamentalists. Sullivan explains that “the fundamentalist does not tolerate a diversity of views. There is one truth; and all other pretenders are threats to it, or contradict it . . . Fundamentalists assert a central core idea and then contort or distort reality in order to make it fit their model.” In a world where life and death become entirely divorced from any connection to modern biological understanding, only faith remains. It is faith of a particular type, not science, that drives the belief that the embryo shown in one of the pictures above is a human being, while the other object is not. This sort of faith is not amenable to debate, which is why this will be my final word on the subject.
Lee M. Silver
Patrick Lee and Robert P. George respond: Lee Silver continues to bluster and spin in an effort to depict people who disagree with him as “fundamentalists” who rely on religious faith, rather than science, for their beliefs about matters of biological fact. It is Professor Silver himself, however, who refuses to face up to the scientific facts about human embryos.
The point at issue is whether human embryos are or are not human beings in the embryonic stage of their natural development. We say they are; Silver claims they are not. Here is another way of putting the question: Does the term “human embryo” refer to something distinct from a human being (in the way that terms like “alligator,” “cotton,” and “stone” — or even terms like “human liver” or “human fingernail” — refer to things distinct from human beings), or does it refer to a human being at a certain stage of development (in the way that terms like “infant,” “adolescent,” and “adult” refer to stages of development)?
Plainly, the complete human organism that is now you, the reader, was once an adolescent and before that an infant. Were you once an embryo? If Silver’s view is correct, the answer is “no.” But the truth is that the answer is “yes” — you were once an embryo, just as you were once an adolescent, a child, an infant, and a fetus. The human organism that is now you is the very same organism that began in the embryonic stage and developed by a gradual and gapless process of self-directed growth to the mature stage of a human being. By contrast, you were never a sperm cell or an ovum. The sperm cell and ovum whose union brought you into existence were genetically and functionally parts of other, larger organisms — your parents. But the organism — the new and distinct human individual — who was brought into existence by their union is the organism that is now reading these words.
It is the science of human embryology — not the Bible or any other religious text or authority — that tells us that human embryos are indeed what we say they are and what Silver denies that they are, namely, whole, living individuals of the species Homo sapiens. As complete human organisms, and not mere parts of larger organisms, embryos are radically unlike human gametes, somatic cells, organs, tissues, and the like. If provided with adequate nutrition and a suitable environment, and barring accident or disease, a human embryo will, by internally directing its own integral organic functioning, develop himself or herself from the embryonic into and through the fetal, infant, child, and adolescent stages, and into adulthood with his or her distinctness, unity, and identity fully intact. What happens in successful fertilization or cloning is the production of a new and distinct organism — a complete individual member of the species in the initial (embryonic) stage of its life. None of Lee Silver’s bluster and spin can make that decisive fact disappear.
The basis of Silver’s denial that human embryos are human beings is his remarkable claim that human embryos are equivalent to human embryonic stem cells. He argues that, since nobody believes that stem cells are human beings, no one should believe that embryos are human beings. But Silver’s premise is not only remarkable, it is indefensible. In a previous posting, we identified the errors in Silver’s attempt to defend it by reference to the possibility of tetraploid complementation. Silver has not made any effort to resuscitate his argument or respond to our refutation. We also observed that if Silver’s remarkable claim were true, other scientists — particularly human embryologists and stem cell scientists with greater expertise than Professor Silver — would confirm it. Why have they not? Silver’s answer is as remarkable as his claim itself. He asserts that scientists know the truth, but they are deliberately hiding it from the public for fear that if it were revealed people would demand new restrictions on stem-cell research. There is no polite way to say this: Professor Silver’s suggestion that there is a massive scientific deception or cover up is ridiculous.
Equally ridiculous, and grossly hypocritical, is Silver’s claim that we hold a position that is not amenable to debate. This series of exchanges with Professor Silver began when (in an article in Science and Technology News and in his book Challenging Nature) he accused us of basing our position that human embryos are human beings on a “hidden theology.” Silver claimed that our argument for this position depended on the proposition that a thing either is or is not a human being. In our October 3 NRO article, we provided a formal (and we believe decisive) refutation of the argument by which Silver proposed to show that we were implicitly relying on theology in our argument for the proposition that a human embryo is a human being; but Silver has provided no answer at all to that refutation. Moreover, in that same article we presented two additional philosophical arguments to support the proposition he claimed we were relying on theology to believe. But he has offered no reply whatsoever to those two arguments.
While consistently failing to engage the counterarguments we have advanced against him, Professor Silver did offer three arguments against the conclusion we draw, namely, that human embryos are living members of the species Homo sapiens – human beings in the embryonic stage of development. In our October 19 NRO article we analyzed each of these arguments and showed that each is unsound. But — like the argument we presented against his original charge of “hidden theology” — these arguments too have received no reply whatsoever. That is, Professor Silver has not even attempted to show that our arguments are defective. Nowhere does he even try to demonstrate that we have relied on a false premise or proceeded on the basis of an invalid inference.
Instead, Silver simply reprises his bald assertion that we hold our belief that human embryos are embryonic human beings on faith “entirely divorced from any connection to modern biological understanding.” Yet, we have presented a wealth of evidence, cited standard and authoritative scientific texts, and invited Silver to identify factual or logical errors in our arguments. Where he has attempted to do so, we have responded by identifying with specificity errors of fact and logic in his critique of our claims. We have offered extended and detailed arguments based on experience, science, and philosophy — at no point appealing to any authority save the authority of reason itself. We deal in the currency of reasons and arguments; Silver replies with name-calling and arm-chair psychoanalysis. But these antics cannot obscure the fact that Silver has simply left our arguments unrebutted. Presumably, if Silver had answers to our points he would supply them. As it is, he is reduced to the shabby tactic of labeling us “fundamentalists” and then — in perhaps the most amusing of his diversions — casting about for some authority to validate the charge. What authority does he come up with? To whom does he appeal as an expert to distinguish true Catholicism from fundamentalism? He invokes the authority of the polemicist blogger Andrew Sullivan. Res ipsa loquitur.
It also is surprising to find Professor Silver, of all people, responding to the barrage of biological evidence we have adduced, by appealing to appearances (albeit enhanced by extremely sophisticated magnification) in an effort to salvage his position. Of course, the fact that humans in the embryonic stage don’t look like humans at later developmental stages is simply irrelevant to the question whether they are in fact human beings at an early developmental stage. The fact that Joseph Merrick — the “Elephant man” — didn’t look like other human beings did not mean that he was something other than a human being. Yet, those who relied on appearances for their judgments could not grasp his humanity, prompting him to exclaim: “I am not an animal. I am a human being. I am a man.” Indeed, he was. By the same token, the fact that an embryo looks like certain non-embryonic clumps of cells does not mean that it is the same thing as a non-embryonic growth or cellular system or a collection of stem cells. To suppose otherwise is to imagine that a sleeping human being or a human being in a temporary or long-term coma is the same thing as a corpse, or that fool’s gold is gold, since they can appear to be identical before inquiry establishes that the sleeping or comatose human is alive and that the fool’s gold is actually pyrite.
But no one has ever asserted that embryos and certain non-embryonic entities or collections of cells are always visually distinguishable or that they are different kinds of things only if they are visually distinguishable. Everyone in this debate knows, and has assumed all along, that embryos at very early stages of their development and certain non-embryonic entities or collections of cells can look alike. Our proposition, fully supported by the standard authorities in human embryology (more on that in a moment), is that scientific inquiry — by observation of their manner of behavior and by genetic and epigenetic analysis — can distinguish them as radically different kinds of things.
Of course, we are assuming — on Professor Silver’s word — that what one of the two micrographs depicts is, in fact, not an embryo but a collection of stem cells. We further assume (for otherwise the case would not be interesting or constitute any sort of challenge) that what he describes as a “bunch of embryonic stem cells” is not, in fact, totipotent — that is, the cells do not constitute a complete, functioning human organism that, if provided with a suitable environment, will by an internally directed process develop itself towards the mature stage of a human individual. If what he describes as a “bunch of embryonic stem cells” were, in fact, a complete, functioning human organism generated asexually by, for example, some method of aggregating and manipulating stem cells, then it would be indistinguishable from an embryo for the simple reason that it is one — in the same way that a cloned human embryo is an embryo.
So, assuming that Professor Silver is accurately and fully describing the two micrographs and is not simply begging the question by offering depictions of two embryos generated by different means, then one micrograph depicts a developing human individual in the earliest stage of his or her natural development — an embryo — and the other depicts a collection of cells that merely visually resembles a developing human in the embryonic stage. Science here, as it does in so many other cases, shows that — and where — appearances and reality part ways. Application of scientific methods would enable a competent and properly equipped embryologist/teratologist to distinguish an actual embryo from a non-embryonic growth or cellular mass which merely visually resembles it.
But Professor Silver makes a further assertion. He claims, not just that the two look alike, but that, “Even if you could look inside with the finest microscope, it almost certainly wouldn’t help because there is almost certainly no molecule, or combination of molecules, whose presence or absence distinguishes all human embryos from embryonic stem cells.” But Professor Silver is merely repeating a scientific error that we refuted in our October 19 article. If a group of stem cells is placed within the normal environment for the gestation of an embryo — a receptive uterus — they do not develop themselves toward maturity. By contrast, if a human embryo is placed within a receptive uterus it will internally coordinate several changes within itself to develop itself to the mature stage of a human organism. That means that the two (the group of stem cells vs. the human embryo) do differ in molecular arrangement, patterns of gene expression, and in one or more cytoplasmic factors. It is precisely these differences that are critically required for (and constitute corroborating evidence of) the radically different developmental trajectories of the two groups of cells (only one of which shows itself to be a unitary organism).
Consulting the Authorities
Next, Professor Silver says: “In fact, none of the standard texts you’ve quoted — or any other prominent biology textbook used at major nonsectarian universities — actually states that an ‘embryo’ is a ‘human being.’” In all of our writings on the embryo question we have made it clear — indeed, we have repeatedly, explicitly stated — that by “human being” we mean a whole member of the human species (at any stage of his or her development), or complete human organism (though perhaps at an immature stage). And it is a simple fact that the texts we quoted do teach that human embryos are whole living members of the species Homo sapiens and complete human organisms at the earliest stage of their development. Indeed, these texts identify the coming to be of the human organism — the human individual — with the coming to be of the zygote. Speaking of the zygote formed at fertilization, Keith Moore and T.V. N. Persaud say: “This highly specialized, totipotent cell marked the beginning of each of us as a unique individual” (p.16, emphasis supplied). Ronan O’Rahilly and Fabiola Mueller say that, at fertilization, “under ordinary circumstances, a new, genetically distinct human organism is formed when the chromosomes of the male and female pronuclei blend in the oocyte” (p. 8, emphasis supplied). And William Larsen says that the gametes “unite at fertilization to initiate the embryonic development of a new individual” (p.1). (Of course, that individual is not an individual spider or goat. Larsen is talking about a human individual. And he is not talking about a mere part of a human individual, like a bit of human tissue or a fingernail or liver. He is talking about a whole, albeit developmentally immature, human individual, viz., a human being.) Bruce Carlson, a distinguished professor of human embryology at the University of Michigan (a “non-sectarian university,” let us assure Professor Silver, since that kind of thing seems to matter so much to him) and author of a leading text, recently testified under oath as an expert witness in embryology in a case now pending. There he stated explicitly that human embryos are human beings: “the human being is created immediately after fertilization, and the maturation process and growth is a seamless continuum.” Can Professor Silver identify a human embryologist of the stature of Professor Carlson who is prepared to go under oath to contradict him?
In our October 3 NRO article, we began by speaking of “human beings in the embryonic stage of development.” In this same paragraph we said: “The complete human organism — the whole living member of the species Homo sapiens – that is, for example, you the reader, is the same human individual that at an earlier point in his or her life was an adolescent, a child, an infant, a fetus, an embryo.” This is precisely the teaching of Moore and Persaud, O’Rahilly and Mueller, Larsen, Carlson, and other leading human embryologists.
Keeping to the Scientific Question
We have also made it clear that the evaluative question of whether every human individual is a subject of rights is a distinct question from that of whether every human embryo is a human individual. Some philosophers have argued that not all human individuals, or human beings, are persons, and we have presented philosophical arguments to show why that position is mistaken. However, some people use the term “human being” as expressing an evaluative concept, synonymous with “person,” rather than as expressing a biological concept, synonymous with “human individual” or “whole member of the human species.” When Silver says that none of the texts we cited say that human embryos are human beings (or when he challenges us to find one of his Princeton biology colleagues who says that embryos are human beings) he is trading on this linguistic ambiguity and the understandable desire of scientific writers to steer clear of ethical or evaluative questions in describing facts.
But we have made clear that by “human being” we mean the biological reality of a whole, living individual of the human species. And on this the embryology textbook writers are perfectly in line with our view and offer Silver no support at all. The simple question of fact with respect to what the standard embryology texts say is whether they do or do not agree that human embryos, from the zygote stage on, are whole human organisms — whole (though immature) members of the human species. An examination of the short quotations given above, and the longer ones provided in our October 19 NRO article, shows that the standard embryology texts do unequivocally affirm that human embryos are whole human individuals, complete human organisms, individual members of the human species, “human beings” precisely as we have defined the term in our writings. It is what Robert Edwards meant when — speaking of the newly conceived Louise Brown — he straightforwardly and accurately described her as a “microscopic human being.” Writing years after her birth, he noted that the human individual that was by then scampering through the schoolyard was the very same human individual that he had observed in the petri dish: “She was beautiful then,” Edwards declared, “and she is beautiful now.” That embryo was not some pre-human creature that only later became Louise Brown. That was the embryonic Louise Brown — the same individual, the human being — who would a few years later scamper through the schoolyard.
Of course, we have also taken note of the fact that some supporters of abortion and embryo-destructive research acknowledge that human embryos are human beings, but deny that they are “persons,” i.e., individuals possessing inherent dignity and a right to life. Such people typically claim that human beings acquire dignity and rights only after coming into being (if they acquire them at all) and may cease possessing dignity and rights prior to dying. They maintain that some humans (embryos, fetuses, even infants) are not yet persons; others (human beings in permanent comas or those suffering from advanced dementias) are no longer persons; and still others (severely retarded individuals) were never, are not, and never will be persons. They identify “personhood” with possession of the immediately exercisable capacity for a certain level of cognitive functioning. So we have separately argued for the further proposition that every human being, irrespective of age, size, stage of development, or condition of dependency possesses inherent dignity and a right to life. The question whether all, or only some, human beings are “persons” is a philosophical one. In this respect, it is unlike the biological question of whether human embryos are human beings. So the arguments we (and others) advance in support of the proposition that all human beings are persons are philosophical, rather than biological, arguments. Even here, though, we do not appeal to religious faith or authority.
Changing His Mind
This takes us to Professor Silver’s attempt to use Dr. Leon Kass as an authority against our view. Silver rightly emphasizes Kass’s standing as an accomplished scholar in bioethics who holds both a medical degree and a Ph.D. from Harvard in biochemistry. He notes that Kass is the former chairman of the President’s Council on Bioethics and that one of us (Robert George) serves with him on the Council. Silver then quotes Kass as writing, “I myself would agree that a blastocyst [an embryo that is 4 to 9 days post-fertilization] is not, in a full sense, a human being.” Then Silver tauntingly goes in for what he thinks is the kill: “I assume, Professor George, that you’ve had many chances to persuade Professor Kass with your ‘careful argumentation and the relevant biological facts,” and (as far as I can tell), you haven’t succeeded.”
Well, let’s see about that.
We’re delighted that Professor Silver has chosen to bring Leon Kass into this discussion as an authority on the issue in dispute. Kass is a giant among bioethicists and a person whose knowledge of the relevant science is beyond dispute. Moreover, he is a scholar of the highest intellectual integrity: a man who carefully weighs facts and follows arguments wherever they lead — even when the conclusion they generate requires him to revise his position. The quotation Silver is trying to use against us is from an essay written by Kass 28 years ago and reprinted in his 1985 collection entitled Toward a More Natural Science. What Silver does not reveal — we hope it was because he was not aware of it, although that would be odd — is that when Kass republished the essay in 2002 (after his appointment as chairman of the President’s Council on Bioethics) in his widely distributed and much discussed book Life, Liberty, and the Defense of Dignity, he added the following sentence to the relevant paragraph: “One could go even further: the in vitro blastocyst is exactly what a human being is at that stage of human development. Only its extracorporeal location is different.”
On the crucial question of biological fact in this dispute, then, Kass turns out to be a witness for our position and against Silver’s. Even more embarrassingly for Professor Silver in view of his taunting claim that George had failed “to persuade Professor Kass with your ‘careful argumentation and the relevant biological facts,’” Kass has explained his reason for revising his text to include an affirmation of the humanity of the embryo. Writing to George, he said that the reason was “precisely because you persuaded me that my earlier formulation [that is, the one quoted so triumphantly by Silver] was inadequate.” Kass’s difference with us — a narrow but important one — is not on the science at all, but rather on the difficult philosophical question. Even here, though, his position is far closer to ours than to Silver’s. Unlike Silver, he believes that human embryos have a high moral status and deserve respect far above what is owed to stem cells, gametes, organs, fingernails, etc. And although he does not regard human beings in the embryonic stage as having moral status equal to that of newborns, he concedes that the question is indeed difficult, that important philosophical arguments for the opposing position have been made, and that he has less than complete confidence in his own position. For that reason, he has firmly, consistently, and publicly taken the view that we should not treat any stage of nascent human life — which, he holds, at all stages should elicit awe and respect — less well than it might deserve.
There is another bioethicist well known to Professor Silver who disagrees with us far more radically on the philosophical question but has asserted with respect to the biological question the very position we hold and Silver denies. In his book Writings on an Ethical Life, published in 2000, Peter Singer stated that the proposition that a human embryo is, as a matter of biological fact, a human being is not only true, but beyond doubt:
It is possible to give “human being” a precise meaning. We can use it as equivalent to “member of the species Homo sapiens.” Whether a being is a member of a given species is something that can be determined scientifically, by an examination of the nature of the chromosomes in the cells of living organisms. In this sense, there is no doubt that from the first moments of its existence an embryo conceived from human sperm and egg is a human being. (emphasis supplied)
Now we don’t know whether Singer continues to hold this view, though the scientific evidence in its support has only strengthened in the six years since he stated it with such certitude. (On the respects in which the evidence has grown even stronger, see Helen Pearson, “Developmental Biology: Your Destiny from Day One,” Nature, Vol. 418, Issue 6893, 2002. Nature, Professor Silver can be assured, is a “non-sectarian” scientific journal.) For purposes of our debate with Professor Silver, it doesn’t matter. For Professor Singer was then, as he is now, an atheist. He, like Silver, supports embryo-destructive research and abortion; indeed, he even goes so far as to say that infanticide can be morally justified. Unlike Silver, however, he is willing frankly to acknowledge the truth about these practices: they involve the deliberate killing of human beings. They are, to use the words of another candid supporter of abortion and embryo-destructive research, legal philosopher Ronald Dworkin, “choices for death.”
Let us conclude with a reply to Professor Silver’s allegation that we fail to identify a test by which our central claim about the embryo’s status as a complete and distinct organism can be verified or falsified. The test of whether a group of cells constitutes a single organism is whether they form a stable body and function as parts of a whole, self-developing, adaptive unit. Contrary to Professor Silver’s supposition, this test is clearly passed by a human embryo, and clearly failed by a group of stem cells. As we noted, if a human embryo is placed within its normal environment, namely, a receptive human uterus, then (barring accidents or disease) it will actively develop itself by a coordinated series of self-directed changes to the mature stage of a human organism. By contrast, if a group of stem cells is placed within a receptive uterus, this does not occur. The test of whether it is a whole (though immature) human organism is whether the direction of its growth (if it has one) is toward the mature stage of that type of organism. The human embryo clearly passes that test, but the group of stem cells fails it.
An embryo and a stem cell are not the same thing, any more than an adult human and a liver or stomach is the same thing. The embryo, like the adult, is a self-integrating whole, a complete member of the species at a certain developmental stage. The stem cell, like the liver, is merely a part. The human embryo, fetus, infant, child, adolescent, and adult differ not as to what they intrinsically are — they are human beings — but in respect of their age, size, stage of development, and condition of dependency.
Once that biological truth is firmly in view, one can then shift to the key ethical question: Do human beings possess inherent and equal dignity? Or does the dignity of a human being depend upon or vary with his or her age, size, stage of development, or condition of dependency? Our view, which we have defended in various writings, is that the dignity of human beings is inherent and that all of us, as members of the human family, are created equal.
— Patrick Lee is professor of bioethics at the Franciscan University of Steubenville. Robert P. George is McCormick Professor of Jurisprudence and director of the James Madison Program at Princeton University.