Souls, Conceptions, and Tetragametic Chimeras

[Seraphinianus]

Forgive me if this is not the correct forum; please relocate if appropriate.

Tetragametic chimeras are animals that have different DNA throughout their bodies. This is because two zygotes fuse into one biological entity. It is rare in humans (though apparently quite common in marmosets, according to wikipedia), but it means that two conceptions–basically, fraternal twins–can become one human being.

Life begins at conception. In humans, this life is immortal–we have immortal souls. Immortal souls cannot be destroyed. In a chimera of this sort, two conceptions means two souls. Assuming human souls can only be “disembodied” by death, then the formation of a chimera means either the death of one human being, or that one human being has two souls. The latter possibility I find difficult to accept.

The former possibility, that the formation of a chimera is somehow the “death” of one human being, does not seem believable either. Believing that one human dies when a chimera is formed seems like scientific dishonesty to me; it is not an honest description of what is in fact just the abnormal development of one human being. The only reason to hold on to the view that one human being dies is to maintain the belief that life begins at conception. If this belief is in such great tension–a tension which I think I’ve expressed above–with observable nature, I think it should be reformed.

Additionally, I’ve heard over the years–and a quick google search confirms–that a significant majority of conceptions end up in miscarriage. www.miscarriage.about.com, for example, states around 75%. If these miscarriages are all humans will immortal souls (bracketing questions about their final destiny), then I have trouble understanding the central place human life and experience are supposed to play in salvation. The meaning of earthly existence seems unimportant, as does unification to Christ’s temporal suffering, etc–most humans never even spend time outside the womb. This is another consequence of the belief that life begins at conception; I find it troubling.

Please share your thoughts on this matter.

 

[BananaMan]

Very good questions. These seem like two distinct, but related, issues (the chimera case, and the frequency of miscarriages). I do not think they successfully vitiate against the position that the human soul is created at conception. I have two comments in this regard:

1. 
   *]Why does the possibility of death at the time of fusion seem “unbelievable”? Perhaps you mean “uncomfortable”, i.e., it is not a pleasant thought. But being unpleasant does not make something unbelievable. I do not know much about this phenomenon, but it seems to be fairly rare, in which case, if the death of one or both original blastocysts is in fact involved, we aren’t exactly talking about massive amounts of fetal death. But see comment #2 below regarding the uncomfortability about such a possibility. Also, not knowing how this fusion of early embryos occurs, I can’t help but think that if either or both of the embryos are truly alive beforehand (in whatever since of the term “alive”, even if you didn’t think it had a rational soul), some form of substantial change is involved in the fusion; to use Thomistic terms, this means the original substantial form must be replaced (or taken over) by another. This isn’t metaphysically hard to believe at all, at least if you accept, for example, St. Thomas’ basic outlook on physics and change. If two things are joined together and form a new and complete whole, then either one of them was absorbed, and taken over by the other; or both gave rise to a third being. However this happens, it may very well be caused by some “unnatural” situation (i.e., a defect in one or both of them making them easily assimilated; a abnormal sort of positioning or interaction between the twins, etc); such “abnormal” situations, however, can indeed cause death, especially for a very vulnerable being like an early human embryo. This is simply a (hard) fact of life: we are mortal; certain situations (e.g., not having enough food, air, etc.; extreme phsycial forces; bodily abnormalities, etc.) can lead to our death. From the Catholic perspective, this is due to original sin, and we all face the consequences, no matter what our age or location.
   *]Next, I’m not sure where statistic of 75% of miscarriages came from – I don’t see it on the site you linked to. This site lists it as 1 in 3 or 4 (25-33%). In any case, let’s suppose the 75% statistic is true; the question is, what is meant by “miscarriage”? If many of these occur very early (at the zygote or early blastocyst stage) it may simply mean that “conception” didn’t complete correctly – in which case they may have very well NOT been a human being any way: since only a “body” sufficently organised and disposed to receive the human soul can be given one (again, I’m following the thought of St. Thomas, but applying it to modern biology). But let’s assume, for the sake of argument, the most difficult case: even though I am somewhat doubtful about the statistic, for the reasons listed above, let’s assume that 75% of conceptions (i.e., actual human beings with rational souls) die in the womb. There is still no metaphysical problem with this; humans are mortal. It is simply a question of truth: do 75% of (genuine) human conceptions end in miscarriages? If so it would indeed be unfortunate and (somewhat) disturbing. But it is also unfortunate that 100% of humans being will die as some point; this should also disturb us. We all die, some younger than others. This argument, then, is simply another form of the difficulty posed by the problem of evil: why do bad things happen? Why do we die? Why do even the young and innocent suffer and die?
   
   I by no means wish to belittle the latter problem (that of evil); that, perhaps, is the most difficult question any believer can face. As the Catechism says, “there is not a single aspect of the Christian message that is not in part an answer to the question of evil” (CCC 309). In this case, though, it is not so much a question of what sounds nice, but of what is true. While modifying one’s understanding of when conception begins may seem like the best solution, I think it will cause even greater philosophical problems: how does the embryo become sufficiently disposed to receive a human soul if it is not (normally) so disposed at conception? And when does this happen? Granted, this is all a very legitimate discussion: the Church does not state exactly when the human soul is created, though it has tended, in the past few decades, to suggest fertilization or conception; it does, in fact, say we must treat the zygote “as if” it were a person from the moment of conception (i.e., fertilization). And that we should do, in the absence of any hard and certain evidence to the contrary, and the Church clarifying the moral questions differently. I, myself, don’t foresee see any of that happening.
   
   So while I think you raise some very good (and honest) questions and objections – which any of us can appreciate if we listen to them – I do not think they really justify, by themselves, saying that the human (rational, immortal) soul is given after conception. And, as I have suggested above, it may be that the frequency of both cases (the tetragametic chimera, and actual deaths of human/rational early embryos) is not as great as it may seem. But that is for others, who know the facts better than I, to clarify.
   
   -Br. Chris, OP

 

[THP]

I think those statistics are correct. It is understood through our REI literature that about 75% of all conceptions do not end up as live births. They are certainly the result of fertilization however. I suppose you can call it miscarriage, but the majority of the time the woman does not know she was pregnant. About 20% of all known pregnancies result in miscarriage. These usually have an emotional effect on the mother.

I am certainly no expert (I am an MD - OB/GYN) in metaphysics but I have always been troubled by the points brought up by the OP. I seems to me that a convenient explanation or solution would be that life or ensoulment should occur at implantation into the uterine lining. Miscarriage becomes more rare at this point, and the conundrums of chimera and twinning become less problematic.

 

[Seraphinianus]

THP, thank you for your post. I am glad to know that I am not alone.

Br. Chris,

Respectfully, I am going to number my arguments so that we don’t lose track of what’s going on here. I have tried to read your post with thoughtfulness and consideration, please forgive me if I’ve in any way failed.

1. Re: 1), above. I should have made my original post clearer. The reason it I think it is scientifically dishonest to describe the fusion of two zygotes into a tetragametic chimera as “death” is that no cells die during the process. If we believe, with Thomas, e.g., that the soul is the vital principle which vivifies all of an animal, plant, etc., and we believe that cellular life is so vivifed, then these cells are enjoying the same life from conception. No death.
2. You also mention substantial change. If no cell dies, finding a substantial change is putting the cart before the horse. The substance of a human is their soul. We know humans have a soul because they are alive. If no life ceases–i.e. no cell dies–then how can one of these humans change substance–i.e. die.
3. [tl;dr: I don’t agree with Aristotelian physics] In full disclosure, I have increasingly doubted the adequacy of Aristotelian-Thomistic natural science to resolve perplexing questions like this, or to accurately describe the world as we know it. Aristotelian metaphysics is built on the physics; the physics supposed to be based on observations of nature. Nature was filled with eternal motions–i.e. the nature of the spheres, in their primordial (and perfectly circular orbit). Species were as they were because of an unchangeable nature. Rocks had a nature–they fell down because the center of the universe is where rocks go. Modern discoveries have replaced Aristotle’s biology–rather than a form or nature determining as a teleological cause the end form an animal will take, we find that DNA operates as a complicated material cause, and if you change DNA you change the form the animal will take. Rocks in fact fall because gravity and other laws are, as Francis Bacon argued, accidents that cut across the phenomena and inhere in them all insofar as they are material. Likewise for other accidents.

Philosophical principles are either self-evident (non-contradiction), the product of induction from nature, or some deduction therefrom. Aristotelian-Thomism would describe the donation of a kidney, e.g., in this way: the kidney lives donor’s body; it is no longer human and not ensouled. Substantial change. The donee receives the kidney and ensouls it–substantial change, just like, say, when we eat food. This belief is reasonable for an Aristotelian-Thomist because the observations correspond to our hylomorphic principles (which are inductive, not self-evident).

But when we add in discoveries made possible by modern science, I think the scene changes. This kidney possesses all the indicators of cellular life the whole time. If cellular life means that a soul is joined to the cell/body, then this kidney has been ensouled the whole time. If we bracket our hylomorphic assumptions, we don’t induce from a kidney transplant the idea that the kidney undergoes a substantial change; there is no physical manifestation that it gets “a new soul.” Aristotle built his philosophy by examining the doxa, the common opinions based on observation. It seems consistent with this method to look for principles that better describe the world we observe.

This argument is by no means rigorous, of course–please feel free to offer your critiques (though I’d like to keep our focus on Chimeras and conception). I will post this topic in another thread if there is significant interest in discussing it in more depth.

1. Re: your point 2), above. The issue is not one of the problem of evil; at least not for me. I have no difficulty accepting that suffering and death are part of a more perfect universe. My difficulty with 75% of conceptions leading to spontaneous abortions-I hope you’ll forgive me for assuming and agreeing with THP, M.D.–my difficulty is that these souls, these billions of souls, never even participate in the suffering of human life and its trials, the unification of our suffering to Christ’s, or Christ’s earthly life and revelation. These facts (suffering, unification, Revelation) are supposed to be the center of the Creation/Salvation history. The Incarnation is the raison d’etre of all of Creation; God is love, and the Incarnation is the supreme act of love. If 75% of people participate in them in no meaningful way, Revelation, unification, and suffering are more like a well-written subplot than the central narrative.
2. Conclusion: By adopting a different view of how and when and why a human is a human, I think we could avoid the perplexing dilemma presented above (75% of people never part of the Church militant; Chimera problem). This may mean developing and embracing a philosophy that incorporates modern scientific discoveries into its bones, as Aristotle’s did in his day. This leads to difficult problems: can the Church change its teaching that life begins at conception? Is hylomorphic philosophy central to the Church’s doctrine/dogma (“consubstantialem patri,” transusbstantiation, homoousion, etc)? If such philosophy is not central, how are we to interpret dogmas couched in hylomorphic terms?

 

[J_Peterson]

There’s also the issue of identical twins. If we receive a soul at conception, than do identical twins share a soul? I hate to think that God would have to intervene every time this happens to add another soul. I don’t have a source but I heard that many miscarriages happen without the mother even knowing that they were pregnant.

I have a hard time reconciling this stuff too so I generally leave it alone.

 

[Seraphinianus]

The fact that it is difficult to reconcile is why I don’t want to leave it alone. The Catholic Faith is the one true Faith; Catholic beliefs should be the most consistent with what we observe in the cosmos.

 

[BananaMan]

These are all great and thoughtful points! While a more complete response to the Seraphinianus’ comments above would have to wait until I have more time, I have a few initial responses the other comments above:

1. 
   *]Regarding the validity of Thomistic/Aristotelian physics in relation to modern science, I think it would be mistaken to think that the basic act-potency paradigm (the unique and insightful contribution of Aristotle, taken up by Aquinas) is somehow rendered obsolete because of Aristotle’s out-dated cosmology. The former does not depend upon the latter; and it is the former – notions of act and potency, eg., substantial form and matter – that can very reasonably be applied to science. Science, I think, makes more sense with it than without it. We can thank Descartes, Bacon, and the like for dismissing it and giving us our prejudice against it. But this, of course, is a rather large topic, somewhat distinct (though related) to the current one.
   *]Regarding the 75% miscarriage statistic: THP, do you know how the statistic is determined? You said above that 20% of all “known” pregnancies end in miscarriage; how, in turn, can we make statistical claims about all “unknown” conceptions?? If they are not known, how do we have reliable statistics about them?
   *]We need to clarify our terms: “hominization” is more accurate for describing when a rational soul is given to the embryo; “ensoulment” could mean any type of soul (such as a vegetative soul). THP, when you say that implantation should be posited as the moment of “ensoulment”, what do you mean by “ensoulment”? We all know that the zygote/blastocyst is developing before this point in time – do you think that it is not alive? What accounts for its development? Or by “ensoulment” do you mean “given a rational soul” (“hominization”), in which case it has a lesser type of soul beforehand (as St. Thomas thought, not knowing what we do about how embryonic development works)? Or perhaps you suspect the whole notion of “soul” (i.e., a principle of life, not a Platonic soul) to begin with, as outdated by science? In any case, I do not find the argument convincing which chooses a point in time, such as implantation, for “hominization” merely on the basis of avoiding other difficulties; there needs to be a positive reason, not merely a negative one, for why the rational soul is given at a certain point in time.
   *]Mono-zygotic twinning, I think, only presents an apparent difficulty, though it is one that must be considered in this whole debate; it may very well be an instance of a type of “cloning”, in which part of an early embryo breaks off and, being sufficiently disposed for human life, takes on its own unique existence and development (i.e., has its own unique soul). This wouldn’t be “intervention” any more than God creating soul at the usual time – whenever that is.
   
   Seraphinianus, I’ll have to wait to follow up to your own response. I’ve got to run…

 

[THP]

• Regarding the 75% miscarriage statistic: THP, do you know how the statistic is determined? You said above that 20% of all “known” pregnancies end in miscarriage; how, in turn, can we make statistical claims about all “unknown” conceptions?? If they are not known, how do we have reliable statistics about them?

The 75% is actually exaggerated, its more like 60%. 75 was off the top of my head, so I would like to clarify. I had to go back and look up the data from my text book. Most of these studies were done in the late 80s where cohorts of healthy, normally cycling women were given a series either urine or blood pregnancy tests around the expected time of implantation. About 30% would have positive pregnancy tests but go on to menstruate at the normal time. We attribute this to failure of implantation. I often see patients who come in a couple of days late on their period and we are able to detect a pregnancy because our assays for b-HCG (the pregnancy hormone) is now exquisitely sensitive. We would never be able to see anything on ultrasound. These are sometimes referred to as chemical pregnancies.

The number of known pregnancies that end in miscarriage is more like 30%. This of course varies by maternal age, obstetric history, medical problems, etc but if you take all comers its about 30%. This is where the number of 60% comes from. The vast majority of this reproductive “wastage” is do to chromosomal abnormalities or aneuploidy.

Speroff REI text book has a nice graph which shows of all fertilizations (1st two options are preclinical pregnancies and the second two are clinical pregnancies):

• Failure of implantation 30%
• Early pregnancy loss 30%
• Miscarriage 12-15%
• Live birth 25%

We need to clarify our terms: “hominization” is more accurate for describing when a rational soul is given to the embryo; “ensoulment” could mean any type of soul (such as a vegetative soul). THP, when you say that implantation should be posited as the moment of “ensoulment”, what do you mean by “ensoulment”? We all know that the zygote/blastocyst is developing before this point in time – do you think that it is not alive? What accounts for its development? Or by “ensoulment” do you mean “given a rational soul” (“hominization”), in which case it has a lesser type of soul beforehand (as St. Thomas thought, not knowing what we do about how embryonic development works)? Or perhaps you suspect the whole notion of “soul” (i.e., a principle of life, not a Platonic soul) to begin with, as outdated by science? In any case, I do not find the argument convincing which chooses a point in time, such as implantation, for “hominization” merely on the basis of avoiding other difficulties; there needs to be a positive reason, not merely a negative one, for why the rational soul is given at a certain point in time.

• Mono-zygotic twinning, I think, only presents an apparent difficulty, though it is one that must be considered in this whole debate; it may very well be an instance of a type of “cloning”, in which part of an early embryo breaks off and, being sufficiently disposed for human life, takes on its own unique existence and development (i.e., has its own unique soul). This wouldn’t be “intervention” any more than God creating soul at the usual time – whenever that is.

Seraphinianus, I’ll have to wait to follow up to your own response. I’ve got to run…

I appreciate your post and Seraphinianus post, but I am not trained in philosophy so I will need a dictionary and more time to read this (I’m at work).

Of course a zygote and a morula and a blastocyst are alive. Even the haploid gametes (sperm and egg) are alive.

I suppose I was referring to hominization (a term I was unfamiliar with). I do believe in an immortal soul and I was unaware that others had argued for lesser levels of souls.

The reason I think there may be a positive reason for implantation is that the totipotent nature of the blastocyst’s individual cells is largely gone by the time of implantation. Once implantation and invasion of the trophoblast has occurred you know have the potential for a unique individual. There are currently hundreds of thousands of embryos essentially in suspended animation at the 8 cell stage in liquid nitrogen. Given that each of those embryos could theoretically become 8 (or more!) unique individuals, I have a hard time believing that they currently contain a unique rational soul. However, once that embryo is implanted into the uterus we have the potential for growth into a single adult human.

I think you are right that the actual number of miscarriages is likely irrelevant. I suppose it is God’s way of trying to “get it right.” Maybe I am not very sophisticated but having taken care of women who have miscarriages at all stages of pregnancy, the emotional response/toll to a chemical pregnancy is just not the same as an 8wk miscarriage. There is something unique about missing a period and the sense that new life is growing inside of you that is just different than a fertilization that fails to implant and is only incidentally identified. I’m not sure how much that really matters given the topic at hand. I don’t deny that I may be totally off base.

 

[Seraphinianus]

THP and Br. Chris, thank you for your excellent posts. I think they really help to clarify the issues. Let’s narrow down what we’re discussing in light of your statements:

1. We can ignore the high number of miscarriages / failed “chemical pregnancies.” We are not making any judgments on that matter; it is just impossible to make any compelling inferences from the undisputed facts.
2. We can also ignore, I think, problems of twinning and lab-separated octuplets. We haven’t come up with an account of how hominization occurs in those cases, but it is likely less problematic than tetragametic chimera problems (without going further, this is probably because the separation of one totipotent cell from another and the subsequent development into separate individuals is not too difficult to describe as a substantial change; also, the statement “life begins at conception” does not deny that life may begin at other points)
3. Provisional (somewhat imprecise) Definitions:
   Hominization: This occurs when matter, like cells, is joined to a human (rational, immortal) soul.
   Substance: A substance is matter with form, like a human being, a tree, a plant, etc.
   Substantial change: Matter receives a new form. Hominization is a kind of substantial change; as is death (a human becomes a corpse).

The central difficulty posed in this thread is (I think) this:
**A tetragametic chimera is formed when two zygotes, or two blastocysts, fuse–without any cell necessarily dying–and such a chimera can subsequently grow into a single adult human.

1. Can two souls exist in this single adult body? (provisional answer: no)
2. If not, and hominization begins at conception, how can one argue that one of two souls created (two conceptions, two zygotes) separates from its body (its zygote), without a single cell dying?
3. If such a separation cannot occur, hominization does not begin at conception.**
4. is the sticking point. Br. Chris (Bananaman) has argued that a substantial change may occur in one of the cells when it is fused. I believe a substantial change does not occur, and therefore that hominization must not occur at conception. This is because either:
   a) The soul is the form of the body; it is related as form to matter. The matter in this case does not change; no cell dies. If the matter does not change, the matter cannot lose its form. Any loss of form must be predicated on a change in matter.
   b) Even if the matter does change–because now each of the two zygotes is developing into parts of a human body, rather than each developing into a whole human body–this change occurs in both zygotes. If a substantial change occurs, therefore, it must occur in both zygotes because both undergo the same material change. The same material change cannot be a substantial change in one zygote (and hence the separation of a soul from its body) but not in the other. This means that either i) both zygotes undergo a substantial change; their souls are separated from their bodies, and the chimera upon formation is hominized with a new soul, or ii) hominization occurs after conception Because i) seems to entail unresolvable problems of its own, ii) seems to be the answer, and hominization must occur after conception.

Respectfully submitted for your consideration.

 

[greylorn]

Forgive me if this is not the correct forum; please relocate if appropriate.

Tetragametic chimeras are animals that have different DNA throughout their bodies. This is because two zygotes fuse into one biological entity. It is rare in humans (though apparently quite common in marmosets, according to wikipedia), but it means that two conceptions–basically, fraternal twins–can become one human being.

Life begins at conception. In humans, this life is immortal–we have immortal souls. Immortal souls cannot be destroyed. In a chimera of this sort, two conceptions means two souls. Assuming human souls can only be “disembodied” by death, then the formation of a chimera means either the death of one human being, or that one human being has two souls. The latter possibility I find difficult to accept.

The former possibility, that the formation of a chimera is somehow the “death” of one human being, does not seem believable either. Believing that one human dies when a chimera is formed seems like scientific dishonesty to me; it is not an honest description of what is in fact just the abnormal development of one human being. The only reason to hold on to the view that one human being dies is to maintain the belief that life begins at conception. If this belief is in such great tension–a tension which I think I’ve expressed above–with observable nature, I think it should be reformed.

Additionally, I’ve heard over the years–and a quick google search confirms–that a significant majority of conceptions end up in miscarriage. www.miscarriage.about.com, for example, states around 75%. If these miscarriages are all humans will immortal souls (bracketing questions about their final destiny), then I have trouble understanding the central place human life and experience are supposed to play in salvation. The meaning of earthly existence seems unimportant, as does unification to Christ’s temporal suffering, etc–most humans never even spend time outside the womb. This is another consequence of the belief that life begins at conception; I find it troubling.

Please share your thoughts on this matter.

Excellent and coherent set of questions. They are not resolvable, IMO, from any religious perspective of which I know. However, they are immediately resolved by the assumption that the “soul” has always existed and does not owe its existence to God.

From that perspective, discarding a soul because the growing chimera has no room for it, or because of a termination of the gestation process, has no effect upon the soul, except to force it to await a connection with a different growing brain-body system.

The process is not much different from having your dinner reservation cancelled because some senator came in unannounced and took your turn. One can feel offended and make a big deal of it, but there are other restaurants, other tables, and better food elsewhere.

 

[BananaMan]

I have responses to (A) THP and (B) Seraphinius below. I will respond to (C) Greylorn in the subsequent post.

A. THP: thanks for the info. That was helpful. I think your comment that “The vast majority of this reproductive ‘wastage’ is do to chromosomal abnormalities or aneuploidy,” touches upon an important aspect of this whole discussion: inadequately disposed matter – e.g., sufficiently deformed genetically material – can preclude a rational soul from ever being given to a living being. It may be that much of this waste is not true human death. On a less important note, in relation to a comment of yours about sperms and eggs, I would argue (and Aristotle also did) that neither sperms nor are eggs are living organisms; they have a sort of life, but not in the full sense of the term. Sperms, in particular, are perhaps more analogous to wound up springs with stored energy that when released from the male, spend themselves and their stored energy until either they’ve achieved fertilization or burned up their energy. They have no real nutritive power (they don’t consume external resources to replace cells, create energy, or reproduce themselves); they are, in a sense, organic sexual tools of the father. But they do not possess an actual soul, philosophically speaking, even though they have certain living characteristics (namely, motion). But it is not sustainable; it is stored energy given to it by another – the father.

B. Seraphinianus, you commented in 2a) above that “The soul is the form of the body; it is related as form to matter. The matter in this case does not change; no cell dies. If the matter does not change, the matter cannot lose its form. Any loss of form must be predicated on a change in matter.” But a cell need not “die” in the medical sense in order for there to be a substantial change; when two embryos “join”, one embryo “changes” by being absorbed into another individual (or both change by being united into a new individual). It is akin to the absorption of water by the body: when I drink water, and it is absorbed by my body, it becomes part of my body, which is animated by my soul; it no longer exists as “water” simply speaking – but as “human being”. Of course, in our situation it is not an inanimate thing like water that we are talking about, but a living zygote or embryo. In fact, this is more like what happens in an organ transplant – an individual organ, after being removed, does not undergo “cell death” medically speaking, although there is a substantial change, because it is no longer animated by the donor’s soul (his or her principle of living unity). Rather, the removed organ is simply in a state of being potentially alive, and still carrying what amounts to a bit of “interia” of life (physical motion originally given to it by the donor’s soul), but it is not exactly “alive” – at least not in the human sense of being alive – and it must be kept medically alive by external, artificial means. I don’t think it’d be accurate to claim that it has its own principle of life within it. Only when united to another living being does it become fully “alive” again.

It may be, then, that the tetragametic chimera is analogous to an organ transplant; and if both embryos are fully alive before the union, i.e., if both are not especially prone to being absorbed by another due to some significant material defect that would render them inadequately disposed for the human soul (in which case they would not be human beings properly speaking anyway), and if at the union of them a new individual is formed distinct from the original two, even without any medical “cell death”, then the first two embryos have died (in the philosophical sense, not the biological sense), and a new one has been created – a real substantial change has taken place. I don’t see a real philosophical difficulty with this.

It may seem difficult, psychologically or emotionally, or even theologically, to accept that two would die and a third form, but philosophically, I do not think it is difficult to account for. But remember, tetrgametic chimera’s are very rare – they are not the norm.

And I agree with most of your comments, Seraphinianus, though not your conclusion, in 2(b) above. You argued there that either (i) both embryos change into a third, or (ii) hominization occurs after conception. But then you simply assert that “(i) seems to entail unresolvable problems of its own.” But that is entirely what is in dispute. I don’t see what the philosophical difficulties really are; they are apparent, but upon further thought about it, as I’ve tried to illustrate above, I don’t think they really remain. Hominization can still begin at “conception”, and can, in the rare case of these chimeras, also occur at the union of two embryos.

But there is also the question of what exactly happens at the union of the two (apparent) embyros: is the change in both more or less equivalent? Or does one “embryo” (I use quotes to admit ambiguity about its status) retain its own individuality, while another is absorbed? Or do both join, and change into a third? Or is it the case that what makes such chimeras possible is significant physical defects, such that they weren’t fully human being to begin with? Or are they normal, living embryos, which had suffered some abnormal interaction which was forced upon them, so to speak? Any of these options is philosophically possible I think; it’s question of what we can verify empirically and only then interpret philosophically. I do not know exactly what happens, physically, when two “embyros” unite to form a chimera like this.

 

[BananaMan]

C. Greylorn, your proposal, which is also that of Plato (in contrast with Aristotle), is, quite clearly, contrary to the Jewish and Christian notion of God and creation, and explicitly contrary to the Catholic faith (rejected in the 6th century). This thread is presuming the Catholic faith; it is also assuming a much more philosophically sound idea of creation. To admit that a human being, in its soul, “does not owe its existence to God” (as you say), is to deny the human being’s status as a creature. This creates an enormous problem, not only theologically, but philosophically; even Plato, at least in his neoplatonic interpreters, would not have admitted this. To posit eternally existing souls, that do not depend upon God for their existence, is the equivalent of positing many gods – a form of polytheism. Perhaps this is in fact your belief. But what, then, gives creation any unity, if it does not come from one source (God)? Furthermore, positing many eternally self-existing souls does not provide a more elegant account of the issue at hand; you have multiplied first causes (many gods which you call “souls”), we have one (God). The simpler solution is the more elegant. That is one philosophical problem. Another problem is that if you think a soul can come and go into and out of bodies like a restaurant customer does with restaurants, then the you (like Plato) have made the soul into the person; we are no longer living unities; we are more like two separate things (body and soul) that live along-side each other, but do not form one single thing – a person which is a body-soul unity. I, for one, am glad to be a living unity, not merely a soul that hops around from body to body. I do not want to be a ghost in a machine. I want to be a human being.

 

[Julia_Mae]

The fact that it is difficult to reconcile is why I don’t want to leave it alone. The Catholic Faith is the one true Faith; Catholic beliefs should be the most consistent with what we observe in the cosmos.

But those understandings evolve as our knowledge increases.

When the sacred writer talked about Mary becoming pregnant at the action of the Holy Spirit, he didn’t think God put some DNA into one of her eggs. In fact, no one knew women had eggs. The womb was considered an empty space into which the male put an itty-bitty human that grew there. So this is what the Holy Spirit was thought to have done, placed a very tiny person into her womb.

Now, knowing about eggs, it’s popular to think Mary’s ovum was fertilized by Divine DNA. But there is still no reason to think any human DNA was ever involved and the Holy Spirit simply placed a zygote in her womb.

Souls were thought to come with life, at the first breath. Unborn children were not considered alive because they did not breath. Now we know more, and the modern Church, in fact, doesn’t know precisely when it occurs. Sometime before that first breath we believe. (Which any first century woman who had been pregnant could have told them, but they were busy keeping silent.)

The Church simply errs on the side of caution and so we must consider life begins at … what? When the sperm gets inside the egg? No double DNA in the cell nucleus yet, so, nothing is replicating, so, no real fertilization yet, but very high potential. Now the male DNA has to get into the cell nucleus and successfully “mate” and replicate. Ensoulment when it’s in the nucleus? When there is replication? Attachment? Differentiation? … wait…

The fusion of two fertilized eggs happens at the blastocyst stage, as I understand it, not as a zygote. Blastocysts are not differentiated except as outer layer and inner (one becoming the placenta, one becoming the body.)

Do you think souls are “in” bodies? Or are bodies just surrounded by souls? Infused in them? By them?

Do we think God has to follow a bunch of rules men made for Him? Do we think He knows all and decides Himself, on a case-by-case basis perhaps, where a precious human soul needs to be and when?

This is what we call a Mystery. The Church guides us to moral choices based on the best info she has at the time. Other than that, seriously, we are pretty much clueless.

(There seems to be a doctor in the house, I’ll be happy to be corrected if I have the stages wrong somehow.)