Bad science, worse philosophy, and McCarthyite tactics in the human-embyro debate.
[This article was co-authored by Patrick Lee and Robert P. George.]
We have in many places argued for the humanity and fundamental dignity of human beings in the embryonic stage of development and all later stages. In defending embryonic human life, we have pointed out that every human adult was once an embryo, just as he or she was once an adolescent, and before that a child, and before that an infant, and before that a fetus. This is not a religious claim or a piece of metaphysical speculation. It is an empirical fact. 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. From the embryonic stage forward, all you needed for your survival and continued growth towards adulthood along the continuum of human development was a suitable environment, adequate nutrition, and freedom from grave disease.
In short, we have argued — though it is fairer to say that we have pointed out, since the scientific facts are not in dispute — that human embryos do not differ in kind from (other) human beings; rather, they differ from other human beings merely in respect of their stage of development. Embryos, fetuses, infants, adolescents, and adults are not different kinds of being — the way a human, an elk, a spider, a cucumber, and an amoeba are different kinds of being. Embryos, fetuses, infants, adolescents, and adults are the same kind of being at different developmental stages.
Still, Lee Silver in “The Biotechnology Culture Clash,” published in Science and Theology News (July 18, 2006), and more fully in a new book entitled Challenging Nature, insists that our views about the humanity and dignity of the human embryo are grounded in religious beliefs. He accuses us of concocting a scientific sounding case against embryo-destructive research in an effort to impose our religious beliefs on others while evading the constitutional prohibition of laws respecting an establishment of religion.
So Now We’re Fundamentalist Theologians?
Silver says that the claim that human embryos are human beings at an early stage of development is “hidden theology.” This could mean two different things. First, as this claim is presented in the book, Silver asserts that we actually hold our position on the status of the human embryo on theological grounds. We are, he suggests, hiding this fact, manufacturing arguments that sound scientific, but are in reality merely a cover for our real, theological, and indeed, “fundamentalist” grounds.
To describe such a claim as an ad hominem argument is to exaggerate its standing. It is nothing more than ad hominem abuse. Silver knows that we are Catholics, and so he uses that fact to suggest that our real ground for believing that human embryos are human beings is Catholic doctrine. But here he has things exactly backwards. Our ground for believing that human embryos are human beings is the indisputable scientific fact that each human embryo is a complex, living, individual member of the human species. Although our claim does not rest on the authority of the Catholic Church, or any other religious body or tradition, we find the Church’s teaching against human embryo-killing credible precisely because it — unlike Silver’s contrary teaching — is in line with the embryological facts. If “fundamentalism” consists in obstinately clinging to a moral, religious, or political view in defiance of empirically demonstrable findings of science that falsify its premises, we are not the fundamentalists in this debate. It is Lee Silver himself who has fallen into a form of fundamentalism.
The biological fact that human embryos are human beings in the earliest stages of their natural development is, to say the least, inconvenient for Professor Silver. So he commits the very offense of which he accuses us and others who oppose his agenda. He hides his ideology under a veneer of science. But the veneer is easily pulled off and the truth exposed. Just examine any of the major embryology texts now in use in American medicine. What you will find is the teaching that a new human individual exists from the earliest embryonic stage forward. That individual is a complete, though, of course, developmentally immature, member of the human species, whose life — whether it lasts for nine minutes, nine days, nine years, or nine decades — is a human life.
The second thing Silver could mean by his “hidden theology” allegation is that our argument depends on an implicit theological premise, whether or not we are aware of it. In the bulk of his analysis, this seems to be Silver’s claim against us. It is a bold charge, and to support it, Silver would have to show that at least one of the premises of our argument is such that anyone asserting that premise must depend on religious faith for his presumed awareness of it. For example, if one could show that a person could advance a particular argument only if he presupposed that God is three persons in one being, or that God became man — propositions about the inner life of God or about his free choices, and so in principle not provable by reason unaided by faith — then it would follow that the argument depended on a theological premise. So, what religious dogma does Professor Silver find lurking in our premises? What is the unstated religiously dogmatic assumption of our argument? At what point are we “stealthy servants of God” (as Silver characterizes us on p. 116)? The hidden assumption, according to Silver, is the following: that a thing either is or is not a human being (though, curiously, on p. 83 Silver actually quotes Robert George openly asserting this supposedly “hidden” assumption).
According to Silver, “This assumption comes from an interpretation of Genesis by certain religious groups that strictly follow the Bible. Genesis 1:27 says, ‘God created man in His own image.’ And that is interpreted by some as meaning that God created man instantaneously. There can be no such thing as gradual creation because then you have partial man, and man would not be in the image of God. There is no such thing as a partial God. God is absolute.”
This is risible. First, the supposed theological argument grounding the key assumption does not even make sense. Formally, the argument would be: “God is not partial; humans are like God; therefore no humans are partial.” But by this argument pattern one could also conclude that humans must be uncreated, perfect, infinite, and eternal. Is it really likely that such nonsense would be the hidden inference bolstering our assertions?
Second, the idea that a thing either is or is not a human being is not a proposition about the inner life of God or about God’s free choices — propositions beyond the reach of reason unaided by faith. Why assume that a very straightforward proposition about human individuals is something knowable only by religious faith?
Third, many philosophers, both ancient and contemporary, some religious and some not religious (e.g., Aristotle, David Wiggins, Roderick Chisholm, Peter Van Inwagen, E. J. Lowe, and many others) have ably defended this proposition on philosophical grounds.
Fourth, this proposition is part of common sense (a fact that doesn’t by itself prove it, but does provide support for it). Most people believe that they persist through time, and so, by implication, that there is a profound difference between their becoming this or that (say, tall or tan), and their coming to be at all. If I am the same concrete being yesterday and today, then I exist completely at each time that I exist (though I constantly change by acquiring new qualities, changing in quantity, and so on). And if I exist wholly at each time that I exist, it follows that I came to be, that is, began to exist, at once and not gradually. Otherwise, during my coming to be I would exist partially, not wholly. Thus, as common sense would have it: there are degrees in various qualities and quantities, such as colors or sizes, but there are no degrees about whether an individual exists or not; either he exists (however developmentally immature or tiny) or he does not.
Finally, there are strong philosophical arguments in favor of this common sense view. The denial of it logically entails what is sometimes called “perdurantism,” or “the temporal parts view” — namely, that a person is only a series of events or experiences spread out in time, like a baseball game or a song. On this view, the temporal extent of a person is part of what he is, and at any one time he exists only partially, not fully. As a consequence, according to this view, “I today” and “I yesterday” refer not to the same concrete individual, but to different temporal phases of the whole series temporally extended.
Were You You Yesterday?
This view has several grave problems, two of which we will mention here. The first difficulty is that, according to this view, a human being (or any ultimate subject of existence) is the sum of time-slices suitably connected (say, by biological or psychological continuity). But what is a time-slice, and, how could time-slices give rise to a human organism’s (or any organism’s) extension through time? If the time-slice itself does not have temporal extent, then the addition of any number of time-slices to each other will not give rise to a temporally extended series — just as the addition of any number of unextended points will not produce an extended line. On the other hand, if the time-slice of a human being does have temporal extent, then no explanatory gain has been achieved by denying a persisting human being, since one will then (by necessity) have admitted that an individual as a whole can persist through at least some extent of time. But if one must admit persistence through time at one level, why not admit it at the level that common sense and explanatory practice seem to demand — that is, the lifetime of a human individual who persists through time?
A second problem with the temporal-parts view is that, in effect, it actually implies the complete denial of change. On the temporal-parts position, a particular object, such as a human being, is not wholly present at any given time. Rather, just as an object has spatial parts, so that at small portions of space only part of it is present, so (on the temporal parts view) each object has temporal parts. An object, for example an apple, has a part that is present at one time, say on Monday, and another part that is present at another time, say on Tuesday. The apple is composed of different temporal parts or stages. Thus, the apple is green at one temporal stage (Monday) and red at another temporal stage (Tuesday). But on this view it follows that in the strict sense there simply is no change. A flagpole that is green at one spatial part and red at another part does not involve any change; but by the same token, an apple that is green at one temporal part and red at another temporal part involves no change either. For real change to occur, the same subject must first be characterized in one way and then in another way.
But it is obvious that change does occur. Consequently, an object (a substance) is not just a series of events, but exists wholly at each time that it exists. When it comes to be, it must come to be at once (though, of course, once it comes into being it may, depending on the kind of substance it is, grow in size and proceed through various developmental phases towards maturity). Changes can precede this substantial coming to be, changes that dispose the future constituents of the substance more and more to that substantial change. For example, fertilization is a gradual process that results in the coming to be of a new organism. But the organism itself does not exist until the process is completed. Prior to the completion of this process it is not correct to say that the new organism partially exists. (It does not “partially exist” during the process.) When it comes into existence, it comes into existence as a whole organism. But the substantial change itself — the actual change from not existing to existing — must be at once.
Thus, both common sense and philosophical arguments provide strong support for the proposition that human beings cannot partially exist, that a human being either is or is not. It is ridiculous to claim — as Silver does — that this proposition is a hidden theological assumption. (Indeed, it would be ridiculous to classify it as a theological belief, as opposed to a philosophical one, even if it could be shown to be incorrect.)
Part and Whole: A Basic Distinction
In addition to claiming that our position is based on “hidden theology,” Silver presents an argument in the form of a reductio ad absurdum for his denial that early stage human embryos are embryonic human beings. He says: “Embryonic stem cells can develop into an actual person. So, based on the definition of the U.S. National Academy of Sciences, embryonic stem cells are equivalent to embryos. Yet based on the molecular signals that you give the cells, the cells can change from embryonic to nonembryonic and back to embryonic. You can do this easily.” But the first sentence just quoted from Silver is simply false. Embryonic stem cells are functionally parts of a complete organism; they are not themselves complete human organisms. (When separated from the whole human organism, they are no longer functioning parts of that organism; they become mere cells — fundamentally different from whole, though immature, members of the human species.)
A human embryo — precisely because it is a complete member of the human species — can develop towards maturity, given a suitable environment and adequate nutrition. The embryo possesses the genetic and epigenetic primordia and the active disposition for self-directed growth towards the next more-mature stage. But this is not true of a stem cell or even of a mass of stem cells. Like somatic cells that might be used in cloning, they possess merely a passive capacity to be subjected to various techniques of asexual reproduction and so become parts of a new human organism.
Silver bases his claim that “embryonic stem cells are equivalent to embryos” on the fact that mouse embryos can be generated from embryonic mouse stem cells and have all of their genetic makeup, and cell lineage, derived from those initial stem cells. A tetraploid embryo-like entity known, though controversially, as a tetraploid “embryo” (“tetraploid” meaning that the entity has four sets of chromosomes rather than the normal two sets) is developmentally defective, so it can give rise only to trophoblastic cells (precursors of the placenta and associated tissues) and not to the cells of the “embryo proper.” When combined with mouse ES cells (ones that have a normal number of chromosomes), these can produce a chimeric mouse in which the cell lineage of its placenta and associated tissues is derived from the tetraploid entity (or “embryo”), and the cell lineage of the mature embryo (the “embryo proper”) is derived from the ES cells. From this, Silver infers that ES cells can by themselves develop into the mature stage of the animal (see his book, p. 140) — “by themselves” in the sense that the DNA in all of the mature embryo’s cells is identical to that in the ES cells.
Since it is often argued that human embryos are human beings because they can “by themselves” develop into mature humans, it follows — on Silver’s argument — that embryos and stem cells are (ontologically and morally) equivalent. But since it is absurd to think that ES cells are human beings, it also is absurd (Silver’s argument continues) to think human embryos are human beings.
This argument is a descendent of an earlier, similar argument that embryos are morally equivalent to somatic cells (such as skin cells) because somatic cells can produce mature human beings by way of cloning via somatic cell nuclear transfer (SCNT). In SCNT the nucleus of a somatic cell is inserted into an enucleated ovum and they are caused to fuse by an electrical stimulus, the result (if all goes as planned) being a cloned embryo. It was argued (by Ronald Bailey, Peter Singer, and others) that since somatic cells are converted into embryos, and these grow into mature members of the relevant species, human embryos have no more exalted a status than ordinary somatic cells, such as skin cells. Some critics of this argument replied that the somatic cells cannot by themselves develop into mature humans, which is certainly true. The important point, though, is that the SCNT process makes use of the somatic cells to create entities of a different nature — using parts of human organisms (somatic cells) to make new complete human organisms at the embryonic stage of development.
Thus, in the context of SCNT cloning, somatic cells are analogous to sperm and oocytes (parts of whole organisms) rather than to embryos (which indeed are whole organisms). But Silver thinks production of a mature mouse by tetraploid complementation answers that reply: In this process, the more mature organism is derived directly from the ES cells, so the ES cells do (according to Silver) in some sense by themselves become whole embryos. He thinks this process shows that, just like embryos, ES cells also can develop into mature members of their species if they are just given a suitable environment.
Confusion over Tetraploid Complementation
However, this fundamentally misinterprets the results of tetraploid complementation. In addition, it repeats the mistake in the earlier argument. Tetraploid complementation does not show that the “entire embryo” can be derived from ES cells. The embryo (or embryo-like entity) generated from tetraploid complementation is a chimera, with parts derived from the original embryo that was induced to become tetraploid and parts derived from the ES cells. The placenta and other organs generated from the tetraploid cells are parts of the embryo. They are bodily organs that function only during embryonic life, but they are bodily organs none the less — analogous to baby teeth, which also function only during a portion of the animal-organism’s life cycle. The placenta is a vital organ of the embryo, and it is not directly made by the ES cells.
Moreover, in tetraploid complementation, the ES cells do not by themselves generate a mouse since they do not by internal self-direction develop into a mouse. So the ES cells are not mouse embryos or their equivalent, and never were. True, the mature mouse’s cell lineage is completely derived from the ES cells, but an analogous point is also true in SCNT cloning — the DNA of the mature mouse or sheep or other animal is identical to that of the donor somatic cell (although the cytoplasm from the enucleated ovum also has a determinative effect). The central point is that, just as in SCNT cloning, so here: the manipulation (in this case, the combining of the ES cells with the tetraploid entity or “embryo”) generates a new type of biological entity. This is demonstrated by the profoundly new type of behavior observed in the entity produced by the process or processes of tetraploid complementation. The manipulations involved do much more than merely release an inner capacity of the stem cells. The combining of the stem cells with the tetraploid embryo does not merely place these cells in an environment hospitable to the process of organismal development. Rather, it transforms them from functional parts to components of an actively developing whole organism. Or, more precisely expressed: the combining of the stem cells with the cells of the tetraploid embryo generates a new organism, an organism that is not a stem cell.
The tetraploid complementation procedure is simply a type of cloning. In the most common form of cloning — SCNT — a new organism is generated; it comes into being as an embryo which immediately begins actively developing itself into the more mature form of the whole organism it now is. Completely analogous to what occurs in tetraploid complementation, the new embryo in SCNT cloning has the same genetic code as the somatic cell. The combining of stem cells with a tetraploid embryo does to the mouse stem cells what fusing an enucleated ovum does to a somatic cell in SCNT, the procedure that generated Dolly the sheep and many other cloned mammals — namely, it produces a distinct, whole organism.
So a stem cell does not “become” an embryo (the way an embryo truly does become a fetus, an infant, a child, an adolescent, and an adult). Rather, many stem cells are used in a cloning process that, if successful, results in the production of a new and distinct organism. The proof that this results in an entirely new and distinct organism is that it has a radically different trajectory of growth.
Thus stem cells are not equivalent to embryos. They lack the defining feature of embryos, namely, the internal active disposition to develop themselves to the mature stage of the organism of the relevant species. If placed within an environment suitable for the development of human embryos, human stem cells do not do what embryos do. (The crucial fact that by themselves — that is, when not introduced into a pre-existing, albeit defective, tetraploid embryo — ES cells produce only disorganized masses of tissue, either embryoid bodies or teratomas, is conveniently ignored by Silver.) Only if human stem cells are joined with other factors so as to generate a distinct and whole organism in SCNT, or in the combining of stem cells with tetraploid embryo-like entities, does an embryo come to be.
Several passages in Silver’s book indicate that he regularly fails to see the significance of the distinction between a whole organism, on the one hand, and a tissue or part of an organism, on the other hand. Thus, he believes our argument is easily refuted by pointing out that a single human skin cell or a teratoma has the same genetic code as other (whole) members of the relevant species. But our argument has never been simply that human embryos are human beings because they have the full genetic code. Rather, we have always argued that their full genetic code, plus (and more importantly) their internal active disposition for self-directed development toward the mature stage of a human, show that they are what the standard embryology texts say they are, namely, distinct and whole (though immature) individuals of the human species.
Stem Cells Are Human Too?
Having assumed erroneously that one can convert a human stem cell into a human embryo and back again quite easily, Silver then says:
So then you can ask, ‘How many human beings are there in a dish of embryonic stem cells?’ If there are a million cells in the dish, and you separate all the cells, then you have a million human beings. But you can then put them back together to form a single organism. What happened to the 999,999 human beings? Robert George would say they all died.
He supposes that this is a decisive argument, but in truth it is a failure. The prospect of actually creating and then killing almost a million human embryos merely by separating cells is a figment of Silver’s imagination.
To the question, “How many human beings are there in a dish of embryonic stem cells” the answer is: none, for stem cells, like other somatic cells, are not human beings.
When Silver asserts next, “If there are a million cells in the dish, and you separate all the cells, then you have a million human beings,” this is simply incorrect. You must do much more than merely separate stem cells in order to generate embryos. Separating them will merely spread them apart. Like a somatic cell, a stem cell must be fused with something else that will transform it from a part into a whole in order to produce an embryo.
But suppose that a lab were successfully to produce a million clones from human embryonic stem cells. How many nascent human beings would you have? The answer is: a million. Of course, no one, to date, has managed to demonstrate success in cloning even a single human embryo, using the methods that succeeded (with much labor) in other mammals. The scenario Silver proposes (which involves producing a million clones in a short time) is not possible today, and perhaps will never be possible. It certainly cannot be “easily done.” Moreover, if tetraploid complementation were successfully performed on human stem cells, only one human organism would be generated from several stem cells, not one embryo per stem cell.
Silver’s errors in dealing with embryological science are nothing by comparison to the extraordinary charges he makes when he turns his attention to political matters. Silver claims to have uncovered an extremist right-wing conspiracy among academics and politicians. He asserts that there is a highly organized effort by “fundamentalists” to gain control over portions of our government and schools, in order to impose a narrow religion on all.
For example, Nigel Cameron is a Christian who claims to present pro-life arguments that can appeal to all people, whether religious or not. Silver first exposes Cameron’s Christianity, quoting from an article Cameron wrote extolling the merits of a theological understanding of medicine. Silver then says that Cameron is using “code words” to convey religious messages to Christians, codes that are not recognized as religious by unsuspecting seculars. He adds: “Cameron’s tactics are taken from the playbook of clever fundamentalists who feel impelled to instill their beliefs as soon as possible, not just in their own children, but in everyone else’s children as well” (p. 102). Again, Silver refers to pro-life intellectuals, including Robert George, as advocates of an ideology who put forth “scientific-sounding arguments to advance their case” (p. 112). He warns of the craftiness of fundamentalists who might lure scientists into arguing with each other: “And so fundamentalists often succeed in transforming a religious debate into a dispute among scientists”(p. 118). One must especially be careful to resist their secular-sounding slogans, which (again) are codes that usually only fundamentalists understand the true meaning of: “Theological terms and ideas are translated into secular-sounding code words and phrases. Sanctity is converted into dignity, the soul becomes life, and the biblical version of morality is presented as a secular bioethics” (p. 118).
Here Silver veers from bad science and even worse philosophy into sheer paranoia. He seems incapable of understanding that the issues about which he is writing are complex and difficult matters on which reasonable people can reasonably disagree. Instead, he assumes that anyone who does not share his opinions is a “fundamentalist” (or dupe of the “fundamentalists”) and is part of a sinister conspiracy to impose a theocracy.
Speaking of Robert George, Silver writes: “Almost certainly, George knows that his so-called ‘scientific evidence’ finds no acceptance among any secular, molecular, or modern developmental biology professor at any major research university” (p. 108). Yet a glance at any of the standard embryology textbooks rebuts this claim. See, for example, Bruce Carlson, Human Embryology and Developmental Biology (St. Louis: C.V. Mosby, 2004); William J. Larsen, Human Embryology, 3rd ed. (2001); Keith Moore and T.V.N. Persaud, The Developing Human, Clinically Oriented Embryology, 7th ed. (2003); and Ronan O’Rahilly and Fabiola Mueller, Human Embryology and Teratology, 3rd edition (2000).)
According to Silver, one should also be wary of conservative think tanks, since they are actually hot-beds of conspiracy: “Evangelical think tanks and lobbying groups proliferate with innocent-sounding names like the Center for Bioethics and Human Dignity, which is directed by the fundamentalist Nigel Cameron” (p. 118). (It would probably be useless to point out to Silver that Dr. Cameron is no fundamentalist, and does not direct the center in question.) Indeed, according to Silver, “The subterfuge is more subtle, but no less potent, in the academic realm. One particular secular-sounding word — natural — frequently infuses the arguments of diverse opponents of biotechnology” (p. 119). Here the entire philosophical tradition of “natural law” reasoning on ethics, whose roots predate Christianity by at least three centuries in the works of Aristotle, becomes a mere façade for the “fundamentalist” conspiracy.
In the end, Silver’s manner of arguing degenerates into a form of McCarthyism. He relentlessly uncovers the Christianity of various lawyers, political figures, writers, physicians, and academics, describing them as “stealthy servants of God.” On his list of Christian “fundamentalists” and individuals collaborating with them (some of whom are Jews) to impose Christian theological dogmas on the entire nation are: Johns Hopkins Medical School surgeon and President’s Council on Bioethics member Benjamin Carson, Oxford University legal philosopher John Finnis, Harvard Law School professor Mary Ann Glendon, Stanford University consulting professor and President’s Council on Bioethics member William Hurlbut, former President’s Council on Bioethics executive director Yuval Levin, and Johns Hopkins Medical School psychiatry professor and President’s Council on Bioethics member Paul McHugh. We wouldn’t be surprised to learn that Silver has a list of 205 card-carrying fundamentalists and their fellow-travelers. Perhaps he will ask others, “Are you now, or have you ever been, a member of the Christian religion?”
Losing It Completely
Going from the ridiculous to the bizarre, Silver extends his conspiracy theory to his fellow scientists. As we have observed, he insists that human embryonic stem cells are the equivalent of embryos because they are (he supposes) capable of developing into human babies. Why hasn’t the public been made aware of this remarkable “fact”? Because, he says, scientists have deliberately kept the public in ignorance: “stem cell scientists know this fact, but they have succeeded in hiding it from the public at-large.” Oh, those stealthy servants of science! There they are, in full knowledge of a key fact about embryonic stem cells, but deliberately covering it up lest the unenlightened masses become alarmed and start slapping new restrictions on legitimate research.
One can be forgiven for savoring the irony here. If, as Silver claims, stem cell scientists have deliberately concealed what they believe to be the truth about embryonic stem cells — namely, that they are equivalent to embryos — then he has established that embryonic stem cell scientists cannot be trusted to be honest with their fellow citizens about facts that might be politically inconvenient. If, on the other hand, what Silver alleges about his fellow scientists is false, then his own credibility collapses.
Silver’s real problem is that the proposition that the human embryo from the zygote stage forward is a distinct, complete (though immature) human being, identical with the child or adolescent which later everyone will recognize as possessing basic rights — that this proposition is fully supported by arguments open to people of all faiths, or of no faith at all. He resorts to name calling (“fundamentalists”), ad hominem abuse, and McCarthyite tactics to distract attention from the scientific facts and their logical implications. Those implications are inescapable once we accept the moral principle that all human beings are entitled to equal concern and respect.
Contrary to what Silver imagines, the great threat to embryo-destructive research is not that “fundamentalists” will take control of the United States government; it is that citizens of every faith, or of none at all, will acquaint themselves with what modern embryology has revealed about human embryogenesis and development.