Suscipe Domine Traditional Catholic Forum

The Parish Hall => The Natural Sciences => Topic started by: Daniel on July 02, 2017, 09:10:26 PM

Title: The soul and identical twins?
Post by: Daniel on July 02, 2017, 09:10:26 PM
What does St. Thomas or Aristotle have to say about this? Clearly the two twins are distinct individuals (and distinct persons in the case of human twins). But they were conceived as a single individual. So at what point does the twin receive its own soul and become a distinct individual?
Title: Re: The soul and identical twins?
Post by: OCLittleFlower on July 03, 2017, 02:10:59 AM
Since God knows what is going to happen before it does, perhaps He creates two souls prior to the division of the embryo?  And perhaps that is one reason for the strong bond between twins -- their souls once shared one body.
Title: Re: The soul and identical twins?
Post by: kayla_veronica on July 03, 2017, 09:03:05 AM
To my knowledge, the Church has not defined the exact moment of ensoulment. We must assume it begins at conception in order to make moral decisions. This is a good point though. I read recently that the split happens within 4-5 days of conception, so there isn't a huge gap there.
Title: Re: The soul and identical twins?
Post by: Quaremerepulisti on July 04, 2017, 11:45:53 AM
The phenomenon of twinning pretty much forces the conclusion that ensoulment does not occur immediately at conception.  St. Thomas and Aristotle won't have anything to say about it specifically because they did not know of its occurrence, although St. Thomas did hold to the opinion that ensoulment occurs 40 days post-conception for males and 80 days post-conception for females.

You can't have two souls "sharing" one body unless you hold to a (heretical) Cartesian idea of the soul-body relation.  It's metaphysically impossible in Thomism, for the soul is the form of the body, and there can't be two forms for the same individuated matter.

Nor is it reasonable to think that, at the moment of twinning, God creates an additional soul which then constitutes the form of one of the separated embryos, because while it is not contrary to His omnipotence to do this, it would falsify Catholic dogma.  This human does not have a mother and father, and is therefore not a descendant of Adam.  He did not arise via natural generation but via another process.

Title: Re: The soul and identical twins?
Post by: Daniel on July 04, 2017, 12:51:03 PM
If the soul is what contains the life, and if ensoulment doesn't occur until after conception, then how do we explain the fact that the embryo's body is alive from the moment of conception? I take it that since it has no soul, then its body must be a part of its mother's body or something? But, if that be the case, then how do we explain in-vitro fertilization? The mother's soul would need to possess two distinct bodies at once, and the mother herself would then be in two separate, discontinuous locations, which I'm pretty sure is metaphysically impossible. Moreover, if the mother has died before her egg was fertilized, then how could her soul still vivify the embryo, seeing as she is now either in heaven or hell or purgatory? Also seems metaphysically impossible.
Title: Re: The soul and identical twins?
Post by: Quaremerepulisti on July 04, 2017, 12:55:27 PM
If the soul is what contains the life, then how do we explain the fact that the embryo's body is alive from the moment of conception?

There is an animal soul, but not a human soul.

Title: Re: The soul and identical twins?
Post by: Daniel on July 04, 2017, 12:57:15 PM
If the soul is what contains the life, then how do we explain the fact that the embryo's body is alive from the moment of conception?

There is an animal soul, but not a human soul.
Wait... so each human receives three separate souls (the vegetable, the sensible, and the rational) at different points in his life? I thought that humans each have but a single soul (a human soul), and that the vegetative and sensitive and intellective faculties were merely separate powers in that soul?

edited for clarity
Title: Re: The soul and identical twins?
Post by: Quaremerepulisti on July 04, 2017, 01:06:46 PM
I thought that humans each have but a single soul (a human soul), and that the vegetative and sensitive and intellective faculties were merely separate powers in that soul?


This is correct; the embryo is not a human prior to ensoulment.  At the moment of ensoulment, the animal soul ceases to exist.

Title: Re: The soul and identical twins?
Post by: Daniel on July 04, 2017, 01:07:45 PM
I thought that humans each have but a single soul (a human soul), and that the vegetative and sensitive and intellective faculties were merely separate powers in that soul?


This is correct; the embryo is not a human prior to ensoulment.  At the moment of ensoulment, the animal soul ceases to exist.
Oh, I see. That seems to makes sense.
Title: Re: The soul and identical twins?
Post by: JubilateDeo on July 04, 2017, 07:50:09 PM
The phenomenon of twinning pretty much forces the conclusion that ensoulment does not occur immediately at conception.  St. Thomas and Aristotle won't have anything to say about it specifically because they did not know of its occurrence, although St. Thomas did hold to the opinion that ensoulment occurs 40 days post-conception for males and 80 days post-conception for females.

You can't have two souls "sharing" one body unless you hold to a (heretical) Cartesian idea of the soul-body relation.  It's metaphysically impossible in Thomism, for the soul is the form of the body, and there can't be two forms for the same individuated matter.

Nor is it reasonable to think that, at the moment of twinning, God creates an additional soul which then constitutes the form of one of the separated embryos, because while it is not contrary to His omnipotence to do this, it would falsify Catholic dogma.  This human does not have a mother and father, and is therefore not a descendant of Adam.  He did not arise via natural generation but via another process.

What about conjoined twins then?  Wouldn't they be two souls with one body?
Title: Re: The soul and identical twins?
Post by: OCLittleFlower on July 04, 2017, 08:09:45 PM
The phenomenon of twinning pretty much forces the conclusion that ensoulment does not occur immediately at conception.  St. Thomas and Aristotle won't have anything to say about it specifically because they did not know of its occurrence, although St. Thomas did hold to the opinion that ensoulment occurs 40 days post-conception for males and 80 days post-conception for females.

You can't have two souls "sharing" one body unless you hold to a (heretical) Cartesian idea of the soul-body relation.  It's metaphysically impossible in Thomism, for the soul is the form of the body, and there can't be two forms for the same individuated matter.

Nor is it reasonable to think that, at the moment of twinning, God creates an additional soul which then constitutes the form of one of the separated embryos, because while it is not contrary to His omnipotence to do this, it would falsify Catholic dogma.  This human does not have a mother and father, and is therefore not a descendant of Adam.  He did not arise via natural generation but via another process.

And yet, with conjoined (Siamese) twins, two souls do inhabit the same body.  Some sets of conjoined twins share a single stomach, for example.  So parts of the body are shared, yet they have two souls.
Title: Re: The soul and identical twins?
Post by: Daniel on July 04, 2017, 09:14:35 PM
My guess (could be wrong) is that each conjoined twin does in fact have his own distinct body. Because essentially there's two bodies which happen to share some parts, right? Not one body that has some "unshared parts".
edit - If it were just one body, the first twin's body would be one and the same as the second twin's body. And if they were the same thing, all parts would need to be shared between the bodies of both twins. But that's not the case.
Title: Re: The soul and identical twins?
Post by: Quaremerepulisti on July 05, 2017, 11:40:19 AM
And yet, with conjoined (Siamese) twins, two souls do inhabit the same body.  Some sets of conjoined twins share a single stomach, for example.  So parts of the body are shared, yet they have two souls.

Yes some body parts are shared, but that does not mean two souls "inhabit the same body", which is impossible.  A soul doesn't "inhabit" a body.  A soul is the form of the body (or the form of a human) - the soul is what makes the body a human body.  It isn't possible for the same individuated matter to have two essential forms.  So each of the conjoined twins has his own separate body and those two bodies are conjoined.  But the conjoined bodies is an aggregate and not a substantial form of its own.

Title: Re: The soul and identical twins?
Post by: Lydia Purpuraria on July 10, 2017, 10:26:55 AM
I thought that humans each have but a single soul (a human soul), and that the vegetative and sensitive and intellective faculties were merely separate powers in that soul?


This is correct; the embryo is not a human prior to ensoulment.  At the moment of ensoulment, the animal soul ceases to exist.

QMR, can you expand on "the embryo is not a human prior to ensoulment," please?  It seems like this could be a problematic statement (if true) for Catholics in opposing embryonic stem cell research, which, I believe, uses embryos/blastocysts only up to 4-5 days old.  But maybe I'm just misunderstanding what you're saying here?

Also, what do you mean by the conjoined bodies being an aggregate in the above post? 
Title: Re: The soul and identical twins?
Post by: Lydia Purpuraria on July 10, 2017, 10:28:07 AM
To my knowledge, the Church has not defined the exact moment of ensoulment. We must assume it begins at conception in order to make moral decisions. This is a good point though. I read recently that the split happens within 4-5 days of conception, so there isn't a huge gap there.

I've read that the split can even occur up to 13 days, although perhaps 4-5 days is the most common time frame (?).
Title: Re: The soul and identical twins?
Post by: Quaremerepulisti on July 10, 2017, 10:57:24 AM
QMR, can you expand on "the embryo is not a human prior to ensoulment," please?  It seems like this could be a problematic statement (if true) for Catholics in opposing embryonic stem cell research, which, I believe, uses embryos/blastocysts only up to 4-5 days old.  But maybe I'm just misunderstanding what you're saying here?

Also, what do you mean by the conjoined bodies being an aggregate in the above post?

I don't see why it would be problematic regarding embryonic stem cell research anymore than it would be problematic regarding abortion - medieval thinkers held ensoulment to occur at 40 or 80 days post-conception and yet they still condemned abortion.  Sure, we don't know the exact moment of ensoulment, but that wouldn't make these things licit, for we are still interfering with the normal generative process, and in addition we are acting with recklessness due to our lack of knowledge.

An aggregate is the combination of two or more things which doesn't have a substantial form of its own.  For instance, a pile of rocks is an aggregate.
Title: Re: The soul and identical twins?
Post by: Lydia Purpuraria on July 10, 2017, 11:11:07 AM
QMR, can you expand on "the embryo is not a human prior to ensoulment," please?  It seems like this could be a problematic statement (if true) for Catholics in opposing embryonic stem cell research, which, I believe, uses embryos/blastocysts only up to 4-5 days old.  But maybe I'm just misunderstanding what you're saying here?

Also, what do you mean by the conjoined bodies being an aggregate in the above post?

I don't see why it would be problematic regarding embryonic stem cell research anymore than it would be problematic regarding abortion - medieval thinkers held ensoulment to occur at 40 or 80 days post-conception and yet they still condemned abortion.  Sure, we don't know the exact moment of ensoulment, but that wouldn't make these things licit, for we are still interfering with the normal generative process, and in addition we are acting with recklessness due to our lack of knowledge.

Thank you, QMR.  I'm thinking of it being problematic in terms of trying to convince others that it's wrong or shouldn't be done, if it's ceded that it's not even a human at the time they are doing their research.  (And the same would go for early abortions.) 

Quote
An aggregate is the combination of two or more things which doesn't have a substantial form of its own.  For instance, a pile of rocks is an aggregate.

I'm still trying to get this in my mind, so bear with me.  But wouldn't conjoined twins be something different than an aggregate, since they at one point were one substantial form that for whatever reason was halted/disrupted in the process of splitting and becoming two substantial forms?  Or what am I misunderstanding here?

Thanks again.
Title: Re: The soul and identical twins?
Post by: CilantroTamales on July 30, 2017, 07:48:24 PM
My belief is that identical twins each has a soul - even as far back as conception.  A single-cell human is made up of 1000s of molecules, maybe millions of atoms, that are eventually going to split.  Why can't they already hold the souls?  I.e. the first thousand molecules have soul "A" and the other 1000 have soul "B".  In other words two souls are not "sharing" one body, they each have their own distinct physical characteristics.  Basically take the budding "video" and run it backwards (all the way to conception), you could technically be able to trace each back to their own molecules, atoms, etc.

Full disclosure: I have absolutely NO expertise in this matter.  My twins are fraternal.  My brother's twins appear to be identical but we've never discussed this concept before.  Obviously, if the Church teaches something different than what I've said, then I disavow the above.  :)
Title: Re: The soul and identical twins?
Post by: Kreuzritter on April 05, 2018, 08:29:46 AM
Nor is it reasonable to think that, at the moment of twinning, God creates an additional soul which then constitutes the form of one of the separated embryos, because while it is not contrary to His omnipotence to do this, it would falsify Catholic dogma.  This human does not have a mother and father, and is therefore not a descendant of Adam.  He did not arise via natural generation but via another process.

That last claim makes no sense: the conclusion would follow anyway, regardless of when the body were ensouled. The spiritual soul is not a product of natural generation but of a divine act, and the corporeal twinning is anyhow a result of "another process" and not the immediate result of the fertilisation of an egg. Further, "arise" here is not defined and it's not clear which definitons would or would not allow the product to be a descendant of Adam, the latter again being undefined.

In any case, this claim of yours is contradicted by scripture: "And think not to say within yourselves, We have Abraham for our father. For I tell you that God is able of these stones to raise up children to Abraham." (Matthew 3:9) God is able to turn stones into descendants of Adam, and that's certainly not by "natural generation"!

On the other hand, if you admit of conjoined twins that

Quote
It isn't possible for the same individuated matter to have two essential forms.  So each of the conjoined twins has his own separate body and those two bodies are conjoined.  But the conjoined bodies is an aggregate and not a substantial form of its own.

then there is no reason that the embryo before twinning could not be an aggregate of two conjoined bodies: why can there not be two corporeal substances seemingly sharing the same material accidents and a volume of space as a kind of mixture? Indeed, you admit that despite sharing single organs and limbs there are nevertheless are two distinct bodies here, though you never define where one body begins and another ends or even wherein their distinctness and individuality consists. For example, if conjoined twins both have control over a particular limb, to which body does it belong? If it belongs to both, then why not the "whole body" in the same sense? If to one only, what does that even mean?

What about this case where they can see through "each other's" eyes and feel one another's pain?

http://www.dailymail.co.uk/news/article-1331769/Doctors-stunned-conjoined-twins-share-brain-thoughts.html