Personhood in the abortion debate

I’ve recently had an online debate with a pro-choice girl, who made the argument that an embryo, even though it is alive since conception, is not a human person until a later stage of developement, because it has not yet the cognitive faculties (such as intellect and will ) that are part of what a person is.
I’ve noticed that the common definition of personhood, even in Catholic philosophy and theology (though the Church hasn’t made any dogmatic definition on the subject yet, as far as I know ), at least since the time of Boethius, is “individual substance of rational nature” (Liber de persona et duabus naturis contra Eutychen et Nestorium, III ).
Thus, theologians such as Saint Thomas Aquinas developed three fundamental criteria of personhood:

  • individuality: a person is distinct in itself and from the others;
  • substantiality: a person is a union of matter and form, not for accident;
  • rationality: a person has an intellectual nature, wich involves at least the potentiality of consciousness.

An embryo meets the first two criteria, but not (at least in actuality ) the third one, because it still doesn’t have a functioning mind immediately after conception. That’s also why Saint Thomas Aquinas didn’t recognized the embryo as a human person until a later stage of developement (even though his argument was philosophical rather than biological, the question being about insoulment ).
I’ve answered this argument by stating that an embryo, since the moment of conception, has already in itself all the necessary elements to develop into a conscious being, and such developement will naturally and necessarily occur if no external contingent cause interferes, so it’s reasonable to treat it as a human person with basic human rights.
She admitted her inability to prove my counterargument wrong, but still wasn’t covinced by it.

So, I have two questions:

  1. Is the traditional and common definiton of personhood necessarily incompatible with the current understanding of the Church on the human nature of the unborn? If so, should Catholics abandon it? If think abandoning that definition for a new one would be tricky, because it could have serious implications in Christology and Trinitarian theology…
  2. Do you find my counterargument convincing? If not, why?

that would mean its ok to stab a mental patient in a psych ward to death, so that’s obviously a false standard

No since as you point out the baby has the “potentiality of consciousness” since it has all the “necessary elements to develop into a conscious being” so the third element is met and the other two aren’t even close

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Yes, I’ve made that argument in the debate, but she simply answered that mentally instable people without the ability to intend and will still have a functioning mind, while an embryo immediately after conception doesn’t. I don’t think such an argument makes a lot of sense.

then she needs to define “functioning mind” if that excludes intellect, will and rational decision making. Good luck with that. The only one she can come up with will be “chemical reactions” which just so happens to be what is occurring in the developing baby, thus it also has “functioning mind” per that definition

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Excellent point

What do you mean by that? An embryo does meet the first two criteria, because it is really distinct from other beings and is a union of matter and form (wich, in the case of a human life, means a union of body and soul ).

It is actually even more than that. The biological developement of an embryo is an ongoing process of actualization, not just mere potency.


I made a similar post not too long ago: Help with a Secular Defense for the Personhood of the Unborn

I think the best answer I got there was that a fully convincing secular defense for the personhood of the unborn is impossible to make, because life only has the value that God gives it. Without God, there is no objective truth to be found in philosophy. Everyone decides morality for themselves. If someone is made aware that an empryo is biologically a unique human being with the natural capacity for all the capabilities we have developing from the moment of conception guided by DNA, and they simply reject that as sufficient criteria for personhood, what more is there to say?

Attainment of the actual use of reason (morally responsible) is not the criteria of the rational being but rather having a rational soul. The rational soul with the physical body is the person, per St. Thomas Aquinas. The soul and body are created together at the same time.

St. Thomas Aquinas wrote in the Summa Theologiae > First Part > Question 75 Man who is composed of a spiritual and a corporeal substance: and in the first place, concerning what belongs to the essence of the soul > Article 4. Whether the soul is man?

Objection 2. Further, the human soul is a substance. But it is not a universal substance. Therefore it is a particular substance. Therefore it is a “hypostasis” or a person; and it can only be a human person. Therefore the soul is man; for a human person is a man.

Reply to Objection 2. Not every particular substance is a hypostasis or a person, but that which has the complete nature of its species. Hence a hand, or a foot, is not called a hypostasis, or a person; nor, likewise, is the soul alone so called, since it is a part of the human species.

Summa Theologiae > First Part > Question 90
Article 4. Whether the human soul was produced before the body?

Objection 3. Further, the end is proportionate to the beginning. But in the end the soul outlasts the body. Therefore in the beginning it was created before the body.

Reply to Objection 3. That the soul remains after the body, is due to a defect of the body, namely, death. Which defect was not due when the soul was first created.

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That’s another example of something on wich Saint Thomas Aquinas would have changed his mind, if he had had the scientific knowledge of our time (another example being the idea that the woman is a defective male, something Aristotle wouldn’t have come out with if he had known about the existence of the female ovum… ). This still leaves most of the philosophy and theology of the Angelic Doctor untouched, though.

Which part of that are you saying he would change his mind on? Why do you think he would change his mind on that? The only thing science has changed is our awareness of exactly when a unique human body exists. It still holds true that a rational soul exists with that body and makes a person.


I mean its not close in that the embryo does meet those criteria

Right but that wasn’t the question. The question was whether an embryo meets the third rationality prong of the definition.

I would ask her, what species is the fetus in the woman’s womb than if it isn’t human? Every other animal is defined as that animal, biologist students will disect a pig fetus and call it a pig fetus. USA federal law makes it illegal to sell or break fertilized bald eagle eggs because they are bald eagles. So why do we give one standard to all the natural world but then give a lesser standard to other humans?
I think the best way is to be respectful and ask questions to let her see the double standard and why it doesn’t make sense.
Also a human has different (lesser) cognitive abilities when they are sleeping or drunk, doesn’t make them less human and it sure doesn’t give anyone the right to kill them

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Saint Thomas Aquinas believed that all the necessary elements for the developement of a body were in the male seed (something that he had taken from Aristotle and that modern biology has proven wrong ), but that the seed didn’t become a human body (wich involves having a rational soul ) until a later stage of developement. Now we know that all the necessary elements for the developement of the body are in the zygote since the moment of conception, and that the zygote is the earliest stage of developement of the human body, wich thus is already there immediately after conception.

Oh, I didn’t see mention of that belief in the reply you quoted, but yeah I’m sure he would accept the new understanding of reproduction.

Give your rational, well-reasoned argument and move on. You are using your intellect while she is responding from emotion or ego.

That is a battle that you cannot win. As it is here, you write primarily for the lurkers, not for those directly engaging you.

Then, you pray.

I would be more careful, the risk of falling into a genetic fallacy is always very high. She could just be wrong in good faith, for example (even though it’s very difficult for such a thing to occur on a matter of natural law, wich leaves a deficiency of the intellect as the only possible explanation, if we want to mantain her good faith ). But I think it’s perfectly reasonable to suppose that you’re right, given the circumstances.

This debate goes on and on and on.
And will likely go on forever and ever.

Regardless, argumentation with a person who justifies the death of the unborn - she having been one - produces heat and little light. That is my point.

If her position is not powered by the ego, then kindly suggest an alternative explanation.

The soul is immaterial per St. Thomas Aquinas so it should not have any change for that. St. Thomas Aquinas accepted the Aristotle reasoning of formation. The soul is uniquely suited to the physical body and formation occurs when a body receives a soul.

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