Part of what happens at this three-cell stage is that one can observe empirically the process of methylation. This observation is important philosophically. Many argue that these very early cells - including the original single-cell zygote up to the 8-cell stage - are "totipotent".29 They explain totipotent cells as the most vaguely directed and least differentiated cells in all of embryological development. Each cell is not yet determined enough to be classified as an individual human being or a part of an individual human being. These cells, they say, have not yet "made up their minds" what they want to be. They can become any number of things. These cells are not differentiated or specialized enough yet.
This portrayal of totipotency, differentiation and specialization is conceptually confusing, incorrect and backwards, as Lejeune notes. Totipotent cells are the most determined and most specialized cells in all of development because they are the least differentiated. Progressively the developing cells loose, in fact, the ability to use this information. In embryological development no information is lost - only the ability to use the information is lost.30 To take an extreme example, a kidney cell contains virtually all of the information that was in the original single human zygote cell. The kidney cell has not lost any of this information - only the ability to use this information. This ability to use or not use the information that is present results in differentiation. Differentiation is partially determined by the process of methylation (which itself is coded in the original single-cell zygote). Through methylation and other processes during embryogenesis, genes are turned on or turned off. When the cell wants to control the use of cellular information, it methylates a molecule to silence that gene, to block or stop its use at a certain point in development. It is this process of methylation which we can empirically observe at the 3-cell stage.
Thus to be so differentiated as a kidney cell is actually a negative in such arguments. The kidney cell cannot direct anything but a small miniscule part of the development of the human embryo or fetus; whereas the original totipotent human zygote contains and can use all of the information only partially used by the later cells. Thus there is nothing vague, undirected or undecided about being totipotent.31 Totipotent cells are suppose to be undifferentiated because they are so "all-specialized". Totipotency is suppose to happen - it is a normal part of human embryogenesis, and is indeed encoded in the original genetic information of the human zygote, as is differentiation. Differentiation, then, really represents the restricted ability to make any "decisions" - a characteristic which totipotent cells do not want.
Next, others argue for the presence of the "rational human nature" at the 2-cell stage, with the completion of the first division and the completion of the genetic input. The two-cell stage already is, like the adult, a moment in the execution of the program 'man'"; it is already the same living being as the human adult arising from it.32 However, we already know that the genetic input is complete at the zygote stage, and that the zygote in fact is the source of the genetic input of the two-cell stage. We also know that the zygote, too, is the same living being as both the two-cell stage and the adult stage. Thus their argument actually argues for the zygote rather than for his two-cell stage!
But to continue, the cells will proceed to divide until about 5 or 6 days, when two cell layers are formed - the trophoblast or outer cell layer, and the blastocyst or inner cell layer. As another example of the need for "human rational ensoulment", some writers have stated that this stage is significant because they can demonstrate empirically that there can be no true human individual present at this time - we have only a genetic individual, not a developmental individual. Only a "developmental individual" can be a person.33 These early cells, they claim, are only "collections" of undifferentiated, "totipotent" cells, and they name them, or designate them collectively, as only comprising a "pre-embryo" (a term, by the way, which is not used by embryologists - only by philosophers, theologians and bioethicists). However, empirically we know that it is "okay" for these cells to be totipotent!
Additional scientific facts which they give to support these claims are the following. They claim that only the cells from the inner layer, the blastocyst, eventually become the adult human being. The cells from the trophoblast layer, they write, are all discarded after birth as the sac and the umbilical cord, etc. Thus, developmentally, the implication is that we are not dealing only with those important cells which will become the adult human being, i.e., the blastocyst, but rather a mixture of "essential" and "non-essential" cells, i.e., a PRE-embryo. A pre-embryo, then, they argue, is not even a human being yet, much less a human person.34
But, again, these scientific "facts" are incorrect, and necessarily lead to incorrect philosophical concepts. It simply is not true that all of the cells from the trophoblast layer are discarded after birth. As can be found in virtually all embryology texts, many of the cells from this trophoblast layer become an integral and essential part of the constitution of the fetus, newborn and adult human being. For example, the cells from the trophoblast layer known as the yolk sac cells become part of the adult gut. And cells known as the allantois cells become part of the adult ligaments, blood cells and urinary bladder.35
Thus these "scientific" facts are incorrect - and therefore so also are their philosophical conclusions about "preembryos" and "developmental individuals" which are grounded on those incorrect scientific facts.
But the same writers continue. It is impossible, they claim, for a human person to be present until at least the 14-day marker event, at which point the primitive streak forms in the embryo. The philosophical significance of this marker, it is claimed, is that until the formation of the primitive streak it is possible for twinning to take place. The totipotent cells "do not yet know whether to be one or two individuals". After 14-days, they claim, twinning is not possible, and thus the organism is finally, "developmentally" one individual.36
But, again, this science is incorrect. As Karen Dawson37 and others point out in these debates - and as is found in every human genetics textbook - it is possible for monozygotic twinning to take place after 14 days and the formation of the primitive streak. For example, fetus-in-fetu twins can be formed up to 2 and 3 months after fertilization, and Siamese twins even later. Also, it is known that "twinning" is sometimes genetically determined and coded in the original human single-cell zygote (as, indeed, is totipotency and differentiation). There is nothing magical, it turns out, about this 14-day stage as far as the concept of individuality and personhood is concerned. If a 2-cell, 8-cell, implantation stage, 14-day primitive streak stage embryo or 4 month fetus splits into twins, that simply means that the original entity was one individual - and now there are simply two individuals. The fact of twinning says nothing about the individuality of the first individual. Indeed, the history of all living organisms is of one individual giving rise to another individual - but one would certainly not then conclude that there were therefore no individuals ever present, or that the former individual was hopelessly "undecided".
Many others38also argue for the 14-day stage, based primarily on the same science as above. Although they would agree that there is an individual present at fertilization - it is only a biological individual. Rational ensoulment cannot take place until after 14 days, at which point there is an ontological individual, i.e., when differentiation is completed and thus a distinct individuality.39 But aside from the problems with the above incorrect science on which they base their own claims, complete differentiation does not actually take place until well after birth. As the embryologist Moore explains:
Human development is a continuous process that begins when an ovum from a female is fertilized by a sperm from a male. Growth and differentiation transform the zygote, a single cell formed by the union of the ovum and the sperm, into a multicellular adult human being. Most developmental changes occur during the embryonic and the fetal periods, but important [developmental] changes also occur during the other periods of development: childhood, adolescence, and adulthood... Although it is customary to divide development into prenatal and postnatal periods, it is important to realize that birth is merely a dramatic event during development resulting in a distinct change in environment. Development does not stop at birth: important developmental changes, in addition to growth, occur after birth... Most developmental changes are completed by the age of 25.40
Thus differentiation and development are not really completed until well after birth - certainly a 14-day embryo is definitely not completely differentiated. Thus their argument fails. Still other writers argue for 14 days because the formation of the primitive streak signals the beginning of sentience (or the ability to feel pain). However, it will become clear below that true sentience is also not complete until well after birth.
Another example of the second kind of argument - where the focus is either the capacity for "rational attributes", or for sentience - is about 8 weeks or several time-markers after that. Personhood, they argue, does not begin until the dawning of or the maturation of the physical substrate of human consciousness, self-consciousness, or sentience - i.e., the formation of the nervous system and/or the brain. But the fact is that complete physiological brain integration is not complete until many months or years after birth,41 just as the complete exercising of "rational attributes" is not possible until years after birth.42 Yet there is already a movement by some in legal jurisprudence to formalize the legal concept of "brain birth" to denote that point in time biologically when there is present a "person", as a parallel to the already legal criteria of brain death. Criticisms of these claims come, for example, from Gareth Jones, a neurologist, who rejects the arguments that we can determine the biological point of either "rational attributes" or sentience. As he states, the parallelism between brain death and brain birth is invalid. Brain death is the gradual or rapid cessation of the functions of a brain. Brain birth is the very gradual acquisition of the functions of a developing neural system. This developing neural system is not a brain. He questions, in fact, the entire assumption and retorts that there are no physiological neurological reasons for concluding that an incapacity for consciousness becomes a capacity for consciousness once this point is passed! Jones continues that the alleged symmetry is not as strong as is sometimes assumed, and that it has yet to be provided with a firm biological base!43
Examples of the third category of arguments include claims that personhood requires the actual exercising of a particular capacity. When the focus is "rational attributes", a "person" is defined necessarily as a young child or adult, and infanticide is openly acknowledged and promoted. For example, many writers such as Peter Singer44 (yes, the animal rights person) argue in the literature for infanticide of even a normal healthy infant!45 46 47 If, he argues, a normal new-born baby can not act rationally (as described above), then it is not a subject but only an object - and we can therefore use it in destructive experimental research if we rational agents so chose. In Singer's own words:
Now it must be admitted that these arguments apply to the newborn baby as much as to the fetus. A week-old baby is not a rational and self-conscious being, and there are many non-human animals whose rationality, self-consciousness, awareness, capacity to feel pain (sentience), and so on, exceed that of a human baby a week, a month, or even a year old. If the fetus does not have the same claim to life as a person, [then] it appears that the newborn baby is of less value than the life of a pig, a dog, or a chimpanzee.48 (emphasis added)
And finally, an example of the arguments for sentience or whole brain integration in this third category of arguments leads necessarily to the same conclusion - i.e. infanticide - because full sentience or full brain integration does not take place until well after birth.
I could continue, biologically, down dozens of "marker events" where it is argued at different points during biological development that until that point there is only a human being and only after that point there is a human person. But virtually every single marker event claimed is also using extremely problematic scientific "data" to back up their philosophical claims of personhood. It would seem that there is more of a problem here than simply the use of problematic science. Perhaps there is also involved - whether consciously or not - the imposition on that science of certain characteristically problematic philosophical presuppositions. What I see is the use of specific metaphysical presuppositions which result in a classic mind/body split. A rough consideration of just how other philosophical schools of thought have defined a "human being" or a "human person", then, might be helpful. Especially in light of the obvious biological continuity present throughout the entire course of embryological development, as well as the specifically human development which we know empirically takes place, how adequately do the other philosophical definitions of a human person reflect or match the correct biological facts as we empirically know them?
I will focus on the definition that is most generally agreed upon these days, i.e., one that is basically "derived" from Descartes49 or Locke.50 Generally, a human "person" is someone who is actually acting at the time in a rational manner. That is, he or she is self-conscious, self-aware, competent, autonomous, logical, mature, conversant, and interacts with the environment and other rational beings around him or her. In short, if one is acting rationally one is a person. If this is true, then 99% of the possible examples of human persons I gave you at the beginning of this discussion are - by definition - not persons, and therefore not deserving of moral or legal protections!
And would you agree that the killing of normal healthy human newborns is morally justifiable? If not, then we have to question, at least, such very rationalistic definitions of a human person, and the metaphysical and epistemological foundations on which they are grounded. If one agrees with the rationalistic premise that a "human person" is defined only in terms of active "reason", then you must agree with Singer's and others' arguments for infanticide. Furthermore, any Cartesian or rationalist definition of a human being as composed of two independently existing substances collapses, since there is absolutely no interaction possible between the physical substrate (e.g., the brain) and the Mind or Reason.
On the other hand, sometimes a human "person" is defined only in terms of the whole soul - i.e., the vegetative, sensitive and rational "souls" all together. Once this soul unites with a body, we then have a human person. It doesn't matter, they say, whether this person is presently acting rationally. What is important is that the rational capacity is present. But if we think about it, we run into similar problems as mentioned earlier. If there are no vegetative, sensitive, or rational directions injected until about 3 months - how did a specifically human biochemical, tissue, organ system get built before 3 months?
Or perhaps we should restrict ourselves to a purely material or physical definition of a human "person". The human person is simply a complex system of molecules, tissues and organs. But this definition has continuously failed in explaining our experience of thoughts, ideas, and concepts, and especially of intentionality, willing, or choosing. It is argued that a "person" is simply a more advanced sophisticated phase of a complex material human being. But aren't we really talking then about a secondary or accidental quality? Surely the definition of the nature of a human person should not be put in terms of only a secondary or accidental phase - however sophisticated it may be. And again, if you are arguing from the materialist premise that a human "person" is defined only in terms of sentience, or the physical integration or functioning of the brain, then you too will have to argue for infanticide, because as pointed out, full physical integration and sentience is not completed until several years after birth.
Given the scientific and philosophical problems inherent in the positions which argue for the various biological marker events of "personhood", can we really accept their conclusions? Are they reconcilable with the correct biological facts? Can you really have a human person without simultaneously having a human being? And vice-versa, can you really have a human being without also simultaneously having a human person?
I would argue no - you really can't split them (except conceptually), as rationalistic or empiricist philosophers are wont to do. And delayed hominization simply does not match up with the correct empirical facts. The definition of a human "being" or a human "person" does not have to be relative - as long as the correct science is employed, and our philosophical definitions actually match that reality. In sum, if given the straight facts, we know that every human being is a human person from fertilization on. But, of course, faith-filled Christians already know that!
* Much of this material is drawn from my doctoral dissertation [Dianne Nutwell Irving, Ph.D., Philosophical and Scientific Analysis of the Nature of the Early Human Embryo (Georgetown University, 1991)]; "Scientific and philosophical expertise: An evaluation of the arguments on 'personhood'", Linacre Quarterly, Feb. 1993; "The impact of scientific misinformation on other fields: Philosophy, theology, biomedical ethics, public policy", Accountability in Research Feb. 1993.
2 Aristotle, Categories, in Sir David Ross, Aristotle (New York: Random House, 1985), p. 20-21; also, Aristotle, Analytica Posteriora 2.19, 100a 3-9, in Richard McKeon (ed.), The Basic Works of Aristotle (New York: Random House, 1941); for Aquinas' similar position, see: The Division and Method of the Sciences, Q6, a.1, reply to 1st Q, pp. 65-66; ibid., Q6, reply to 3rd Q, pp. 71-72; ibid., Q6, a.2, pp. 176-178; ibid., Q6, a.4, p. 90; ibid., Q5, a.3, p.35 (also quoted there in note 21: In I Post. Anal. lect. 1-3, and in De Veritate 1.1); see also George Klubertanz, Introduction to the Philosophy of Being (New York: Appleton-Century-Crofts, 1963), pp. 293-298. [Back]
3 Benjamin Lewin (ed.), Genes III (New York: John Wiley and Sons, 1987), pp. 11-13,17-19, 30, 32, 33, 35, 37, 79, 91, 93-94; also Alan E.H. Emery, Elements of Medical Genetics (New York: Churchill Livingstone, 1983), pp. 25, 34, 65, 101-103. [Back]
4 Keith L. Moore, The Developing Human (Philadelphia: W.B. Saunders Company, 1982, 3rd. ed.), pp. 14ff; also Benjamin Lewin, Genes III (New York: John Wiley and Sons, 1987), pp. 24ff. [Back]
6 See Moore (1982) and Lewin (1987), note 26 supra. [Back]
7 Irving, Philosophical and Scientific Analysis...(1991), see notes pp. 78-80. There is a rapidly increasing volume of this kind of work, e.g., Kollias, G; Hurst, J; deBoer, E. and Grosveld, F. "The human beta-globulin gene contains a downstream developmental specific enhancer", Nucleic Acids Research 15(14) (July, 1987), 5739-47; R.K. Humphries et al, "Transfer of human and murine globin-gene sequences into transgenic mice", American Journal of Human Genetics 37(2) (1985), 295-310; A. Schnieke et al, "Introduction of the human pro alpha 1 (I) collagen gene into pro alpha 1 (I) - deficient Mov-13 mouse cells leads to formation of functional mouse-human hybrid type I collagen", Proceedings of the National Academy of Science - USA 84(3) (Feb. 1987), pp. 764-8. [Back]
9 pace R.M. Hare, "When does potentially count? A comment on Lockwood", Bioethics 2(3), 1988. [Back]
10 pace Michael Lockwood, "Warnock versus Powell (and Harradine): When does potentiality count?", Bioethics 2(3), 1988. [Back]
11 For brevity I will designate Aristotle's theory of substance as a composite, which is the pre-dominant one in his Categories, Physics, the first half of the Metaphysics, and even in many parts of his De Anima, as "Aristotle - proper". Aristotle's theory of substance as form alone - or as only the "rational" part of the form, and the succession of souls as found predominantly in the second half of his Metaphysics and in parts of the De Anima, contradicts the former theory. There is also some degree of contradiction in Thomas - insofar as he sometimes "unblushingly" follows Aristotle's theory of separate form (see, for example, the differences between the definition of a human being and that of a human soul in the De Ente et Essentia in Chapter Two and Chapter Four). [Back]
12 Aristotle, De Anima 1.5.411b, 14-18, (McKeon, 1941), p. 554. [Back]
13 Aristotle, De Anima, 1.5.411b, 24-28, (McKeon, 1941), p.554. [Back]
14 Aristotle, Metaphysica, 3.2.997b18-998a10, (McKeon, 1941), p.721; see also 11.1.1059a34-1059b14, pp. 850-851; for Aquinas, see ST, Ia.q.45, a.4, ad.2, p. 235. [Back]
15 Thomas Aquinas, ST, Ia.q29, a.1, ans., ad.2,3,5, p. 156; ibid, a.2, ans., p. 157; also ST, IIIa.q19, a.1, ad.4.2127; see also, Kevin Doran, "Person-a key concept for ethics", Linacre Quarterly 56(4), 1989, p.39. [Back]
16 Thomas Aquinas, ST, IIIa. q19, a.1, ad.4.2127; see also Kevin Doran (1989), p. 39. [Back]
17 Thomas Aquinas, ST, Ia.q75, a.4, ans., p. 366. [Back]
18 For example, Suarez, McCormick, Ford, Wallace and Bole, infra. [Back]
19 Aristotle, De Anima, 1.5.411b, 14-18, (McKeon, 1941), p. 554; also, 1.5.411b, 24-28, p. 554; for Aquinas, see notes 41 and 39, supra. [Back]
20 As Klubertanz has expressed it, the human soul, being a form, cannot be divided. The ovum and sperm unite, "thus giving rise to a single cell with the material disposition required for the presence of a soul": Klubertanz, The Philosophy of Nature, 1953, p. 312. [Back]
21 Carlos Bedate and Robert Cefalo, "The zygote: to be or not be a person", Journal of Medicine and Philosophy 14(6), 1989, p. 641 - 645. [Back]
22 Thomas J. Bole, III, "Metaphysical accounts of the zygote as a person and the veto power of facts", Journal of Medicine and Philosophy 14, 1989: 647-653; also, "Zygotes, souls, substances, and persons", Journal of Medicine and Philosophy 15, 1990: 637-652. [Back]
23 Benjamin Lewin (ed.), Genes III (New York: John Wiley and Sons, 1983), p. 681; also Alan E.H. Emery, Elements of Medical Genetics (New York: Churchill Livingstone, 1983), p. 93. [Back]
24 In addition to the references on "information cascading", see also those in note 30, supra. [Back]
25 Antoine Suarez, "Hydatidiform moles and teratomas confirm the human identity of the preimplantaion embryo", Journal of Medicine and Philosophy 15, 1990, 630. [Back]
26 Jerome Lejeune, testimony in Davis v. Davis, Circuit Court for Blount County, State of Tennessee at Maryville, Tennessee, 1989; as reprinted in Martin Palmer, A Symphony of the Pre-Born Child: Part Two (Hagerstown, MD: NAAPC, 1989), 9-10. [Back]
27 See, e.g., Richard McCormick, S.J., "Who or what is the preembryo?", paper presented at the Andre E. Hellegers Lecture (Washington, D.C. Georgetown University: May 17, 1990); (pre-publication manuscript); see also, McCormick, "Who or what is the Preembryo?", Kennedy Institute of Ethics Journal 1(1), 1991, p. 3; also see reference in Lejeune, note 51 supra, p. 14. [Back]
28 Lejeune, 1989, p. 14. [Back]
29 For example, Grobstein and McCormick, Ford, Wallace infra. [Back]
30 Lejeune, 1989, p. 17, 20; also see article by Mavilio, where he explains that the modulation of the methylation pattern represents a key mechanism for regulating the expression of human globin genes during embryonic, fetal and adult development in humans. Mavilio et al, "Molecular mechanisms of human hemoglobin switching: selective undermethylation and expression of globin genes in embryonic, fetal and adult erythroblasts", Proceedings of the National Academy of Sciences USA, 80(22) (1983): p. 690; 7-11; see also Alan E.H. Emery, Elements of Medical Genetics (New York: Churchill Livingstone, 1983), p. 103. [Back]
31 See references on "cascading" in note 48, supra; also "transgenic mice" in note 30, supra. [Back]
32 Antoine Suarez, "Hydatidiform moles and teratomas confirm the human identity of the preimplantation embryo", Journal of Medicine and Philosophy 15 (1990): p. 631. [Back]
35 Keith L. Moore, The Developing Human (Philadelphia: W.B. Saunders Co., 1982), p. 33, 62-63, 68, 111, 127; also see K. Chada et al, "An embryonic pattern of expression of a human fetal globin gene in transgenic mice", Nature 319(6055), 1986: 685-9; also G. Migliaccio et al, "Human embryonic hemopoiesis. Kinetics of progenitors and precursor underlying the yolk sac - liver transition: Journal of Clinical Investigation 78(1), 1986: 51-60. [Back]
36 McCormick (1991), p. 4. [Back]
37 Karen Dawson, "Segmentation and moral status", in Peter Singer et al, Embryo Experimentation (New York: Cambridge University Press, 1990), p. 58; see also Keith Moore (1982), p. 133. [Back]
38 Norman Ford, When Did I Begin? (New York: Cambridge University Press, 1988), p. 298. [Back]
40 Keith L. Moore, The Developing Human (1982), p. 1. [Back]
41 G. Gareth Jones (1989), p. 177. [Back]
42 For example, see Singer and Englehardt, infra. [Back]
43 D. Gareth Jones, "Brain birth and personal identity", Journal of Medical Ethics 15(4), 1989, 178. Oddly enough Jones will himself argue for personhood at 6-7 months (p. 177). [Back]
44 Peter Singer, "Taking life: abortion", in Practical Ethics (London: Cambridge University Press, 1981), p. 118; also, see note 84 supra. [Back]
45 H.T. Englehardt, The Foundations of Bioethics (New York: Oxford University Press, 1985), p. 111. [Back]
46 Michael Tooley, "Abortion and infanticide", in Marshall Cohen et al (ed.), The Rights and Wrongs of Abortions, (New Jersey: Princeton University Press, 1974), pp. 59, 64. [Back]
47 Helga Kuhse and Peter Singer, "For sometimes letting - and helping - die", Law, Medicine and Health Care 3(4), 1986: pp. 149-153; also Kuhse and Singer, Should the Baby Live? The Problem of Handicapped Infants (Oxford: Oxford University Press, 1985), p. 138; also, Peter Singer and Helga Kuhse, "The ethics of embryo research", Law, Medicine and Health Care 14(13-14), 1987. For one reaction, see Gavin J. Fairbairn, "Kuhse, Singer and slippery slopes", Journal of Medical Ethics 14 (1988), p. 134. [Back]
48 Peter Singer, "Taking life: abortion" (1981), p. 118. [Back]
49 Rene Descartes, Meditations on First Philosophy, in John Cottingham, Robert Stoothoff and Dugald Murdoch (trans.), The Philosophical Writings of Descartes (New York: Press Syndicate of the University of Cambridge, 1984), 2nd Meditation, 12ff. [Back]
50 John Locke, An Essay Concerning Human Understanding, A.D. Woozley (ed.) (London: Fontana/Collins, 1964), Book Two, Ch. XXXI, pp. 211-12. [Back]
1, 2,