I was thinking the material soul is baked into the matter like the form of a chair is baked into a chair; but it sounds like in your view that is not true. The material soul is not merely baked into the matter as a way materials are arranged to self-actualize: instead, there's a quasi-subsistent unity that directs its self-actualization.

I would say that a robot has no inward self-actualizing principle towards specific ends. It has no substantial form because it is not a substance. It is a mere aggregate of parts and instructions. — Leontiskos

But wouldn't a robot that could mechanistically grow, heal, etc. be self-unified towards certain ends?

Let's call the act of procreating "begetting." I don't know precisely how an oak tree begets an acorn. Does it bear on your point about whether the soul is a unity? — Leontiskos

What I wondering is how would a material soul ever be begotton by another material soul if the soul is a unity which is not merely received by the matter in the same way a chair's matter receives unity from the form bestowed onto it by its creator.

I was envisioning that all Aristotle meant by a material soul (viz., non-subsisting soul), like a vegetative soul, is that it is analogous to how a chair receives its form but that it is a form when received that self-actualizes.

To clarify, are you saying that a robot that has an inward self-actualizing principle towards specific ends (which provide its whatness) does not thereby have a soul?

Do you believe, then, that the soul, even in material souls (viz., non-subsistent souls), is a unity that directs the organism (and this unity is not merely how the parts behave in unison together)? If so, then how does, e.g., an oak tree produce another oak tree with an oak tree soul? I was thinking it would just provide it with the intial spark to get it's parts self-actualizing towards the natural ends of an oak tree.

No, I'm suggesting that for Aquinas, (following the lead of Aristotle), the human intellect is not purely immaterial, it is dependent on the material body. This is actually the reason Aquinas gives for why human beings cannot adequately know God, and separate Forms. The human intellect is deficient in this sense, and that is why we cannot adequately know God until the soul is disunited from the body.

Aquinas, as far as I understand, did think the mind is immaterial. It is not half material and half immaterial (or something like that). In fact, he forwards many arguments for why it is immaterial. Aristotle vaguely alluded to it being immaterial in De Anima, but didn't explicate it like Aquinas did.

I would say that this is a misunderstanding of Aristotle, and Aquinas.

Why? Aquinas thought that, e.g., Angels are pure form and not purely actual.

All matter is potential, but not all potential is matter.

Agreed. To be precise: matter is that which has passive potency, and not that which has potency simpliciter. An, e.g., Angel has active potency but no passive potency; and this is because an Angel has no matter which can be affected; but they still can learn.

The reason why the mind must be immaterial, is illustrated with the tinted glass analogy.

That is a very interesting analogy and I am inclined to agree; but it contradicts your point that humans cannot adequately separate forms. The whole point of the analogy is that if we have a proper intellect (that can apprehend forms with clarity), then it cannot be material AT ALL. Aquinas uses similar arguments to affirm that the mind is completely immaterial; others, as you noted, will use it to deny we have a proper intellect (like Hume).

Let me ask you a point of clarification: would you agree with the following?

A soul is a substantial form and a substantial form is the self-actualizing principle which unites a substance towards its natural ends. A self-actualizing principle can be reduced to the way matter is organized, with the right materials, to self-actualize towards certain ends: there is no unity which subsists that directs the matter itself. Therefore, a robot that has been designed to self-actualize from its own inward principles towards its own natural ends has a soul.

I think you are going to deny this on grounds that I am implicitly thinking in terms of reverse mereology again; but if an unsubstantial form, like that of a chair, is reducible to way the material and organization of parts suit the natural end(s) of 'chairness', then a substantial form is the same but the addition that it is organized to self-organize: this doesn't seem to entail some sort of subsistent unity that directs the self-movement. Let me know what you think.

You made a claim about "things," not "forms." In fact the very vagueness of that word "thing" is doing most of the work in your premise. For example, if you had used "substance" instead of "thing" the premise would not do any work (except against Descartes).

True, but my point is that the mind is not a form and it is immaterial and it is infused with the body that is material; so the question arises: "how does the mind interact with the body in this sort of fusion?". It may not be a hard problem like descartes', but it is still a problem.

I think your basic idea here is correct. Whether or not we want to talk about brains, there will still be "interaction" between the material and the immaterial.

How does that work, then? Is it a mystery we cannot solve?

If the mind is immaterial, then it has to be pure form because there is only form and matter. Are you suggesting an immaterial 'matter' that the intellect would be of?

Aristotle distinguished passive and active intellect, and Aquinas upheld this distinction. Since form is actuality, and the intellect has a passive aspect, I think it is impossible that the intellect is pure form.

From my understanding, something that is pure form is not necessarily purely actual; and what you are noting is that beings which are purely being in idea (such as angels, the mind, etc.) have potency and thusly are not purely actual. That is true, but they are pure form nevertheless because they do not exist in matter.

The potency that an angel has is not like our potency as material beings. My body is what received my form; but an angel is form that was not received by matter.

Perhaps you are denying the distinction between potency and matter; but I would say passive vs. active potency are different, and beings with matter have passive potency.

But, again, then that admits that there is interaction, not in the sense of merely participation in a form, by the mind and body. No?

I guess it is metaphysically possible, but how does that work? Wouldn't there have to be some medium which supplies the imaginery to the agent intellect? Otherwise, why doesn't the agent intellect receive imaginery from other bodies?

According to Aquinas, if I understand correctly, the intellect does not just witness the images: it (viz., the agent intellect) actively extracts the form from the image and passes it along to the understanding (viz., the passive intellect).

The image of this particular apple is used by the agent intellect to extract the form of appleness and received and retained for reasoning by the passive intellect. This seems to imply that the agent intellect somehow operates on images which are material and yet the agent intellect itself is completely void of matter. @Leontiskos, how does the form of a particular thing (which is in the state of sense-matter) get transferred into immaterial thought?

I was using Aquinas' view that brain is capable of and does in fact produce images of things based off of the sensations; but that the agent intellect, which is immaterial, abstracts the form from it for the passive intellect to receive it.

Is the concept of triangularity material? No. Do we interact with it? Yes.

But triangularity is a form: the mind isn't a form. If it isn't a form then wouldn't it have to interact with things? Likewise, wouldn't that have to be an interact where something that is not involved with matter whasoever extracts from matter something?

What I am arguing is more like this:

1. Abstraction of a universal from phantasms requires interaction between the phantasm and the thing which abstracts.

2. The immaterial mind abstracts.

3. The brain produces phantasms.

4. Therefore, the brain and mind interact.

5. A material thing and an immaterial thing cannot interact.

6. Therefore, either the mind is not immaterial or it does not interact with the brain.

By "interact", I mean some sort of process of impact from one to the other; instead of like the participation matter has in receive form. I get form is act, but if there's a subsistent form that can think then I don't see how it doesn't have a part of it that interacts with the matter that is informed in a way not like participation. Somehow the subsistent rational form not only provides the self-actualizing principle for self-development, but it also comes equipped with a mind that somehow interacts with the brain.

namely <If man can have knowledge of all corporeal things, then man's intellect is incorporeal>. Some people use this to affirm the immateriality of the intellect; others use it to deny that man can have knowledge of all corporeal things.

When you say 'man can have knowledge of all corporeal things', is this in the sense that if the a particular of any kind of given to the senses that the mind could abstract out it's form? Or are you saying the mind can know all corporeal things indirectly through testing and self-reflective reason?

I would have to revisit the issue, to be honest. Feser offers accessible blog posts on Thomism, and he has at least four entries on the interaction problem (one, two, three, four). That's where I would begin. The fourth one looks like it is the most concise.

I haven't found a Thomist that addresses tbh. I read Ed Fezer's elaborations and his doesn't focus on how the immaterial mind interacts with the material body. He just vaguely states that there is no interaction problem for hylomorphisists because the soul is the form of the body. The problem I have with that is that it ignores the fact that the immaterial mind is not the soul: the soul would be the form of the body and the mind (together unified); so how could they interact or be unified together like that?

How does the concept of something not being a multiplicity entail it is a multiplicity that is one?

For the point in space, assuming it is real, it would be comprised of three parts: location, form, and matter.

In terms of distinguishing soul and mind, I agree; but that doesn't explain if Aristotle thought the mind is pure/substantial form like Aquinas; and if he does, then how does this not entail a sort of interaction problem even if it is not the same problem as Cartesian dualism? It would be an immaterial mind interacting with a materially body even if the soul is the form of a living being.

By pure form, I just meant substantial form like Aquinas thinks of. A kind of being which is not received by matter: it is just form itself subsisting.

So then we do agree that two purely ontologically simple beings are impossible, but the point if contention is that we can refer to something that is impurely simple as being ontologically simple.

I think this is fine in colloquial speech. We say things like "this is circular" even when it is not perfectly circular. However, I am referring to something that is perfectly indivisible by it being ontologically simple. E.g., I am referring to perfect circularity.

You alluded to indivisibility as not requiring perfect simplicity; but this is only partially true. What you are referring to is something which is materially indivisible WHICH DOES NOT make it completely indivisible. If we had one of these simple particles that you are talking about, it would still be comprised of form and matter; and these are parts of it given that a part is something which contributes to the whole but is not identical to it. You would have to define a part differently and then at that point we are disagreeing merely semantically.

Because they are ontologically absolutely simple; which means they are completely without anything which contributes to the whole but is not identical to the whole. You seem to be referring to a sufficiently simple thing with "ontological simplicity" whereas I am referring to complete and perfect simplicity.

:up:

Do you find his arguments compelling?

Also, if the form of an organism extends to some other substantial, immaterial aspect (of a thinking faculty), then how would that work with interacting with the body? It seems like this view loses that edge that Aristotle has of the form being nothing more than the self-actualizing principle of the body and ends up in Cartesian territory.

How do you support this claim?

Something being ontologically indistinguishable from another thing entails that they are the same thing because the concept of ontological (as opposed to epistemic) indistinguishability is that there is nothing ontologically different about the two things in question.

:up:

You continue to confuse moral facticity with inter-subjective agreement. A moral fact is not traditionally an 'imperative ought' where we ought to do something indpendently of our needs. A moral fact is a statement about reality that describes how it ought to be that corresponds appropriately to reality.

A million people socially accepting norms is not a source of facticity about anything. It would be a fact that they accepted it and that it is a norm, but the norm itself would be non-factual.

I partially agree. I don't think 'form' traditionally refers to some kind of transcendental idealistic 'idea' of a think attributed to it by cognition: it's an integrated actualizing principle of the thing, which is embedded into the thing by a mind.

:up:

I think I get where I was blundering: the fundamental material part would still be comprised of essence and esse, so it would not, in fact, be absolutely simple even if it was not comprised of any other material parts.

I agree but I don't see how this addresses the issue.

E.g., circularity is not a part of a circle; but the atoms that compose the given circle are; and those atoms are comprised of electrons, neutrons, and protons; ...

We would need to ask: does the stuff that is organized towards the whole and the wholes of those organized things and so on go on infinitely or finitely? My point was that if it is finite, then there is some stuff that comprises the second to last member of the causal chain of composition that has no parts. See what I mean?

They have some actuality and some potency. They can learn, turn their attention, will this or that, act here or there, etc. but they cannot grow, decay, or lose form, because they have no matte

How does the idea that they have no matter but pure form not entail that matter is a kind of substrate of pure potentiality?

Likewise, wouldn’t there have to be some primitive constituent of matter that everything made of matter is comprised? Wouldn’t that primitive constituent be absolutely simple and thusly purely actual (along with God)?

For a similar example, there is the human soul, which is immaterial but subject to change, and informed by the body.

But I don’t think Aristotle believed this: this seems more of a Thomist thing. Aristotle just thought that the form of a living-being in virtue of which it is living and unified towards its natural end is the soul. It wasn’t some extra immaterial, cartesian-style thing infused with the body or informed by the body.

Aristotle is quite different in this regard because he hasn't separated out essence and existence. Aristotle complains about the notion of participation in the Metaphysics but Aquinas is able to plumb it more fully and make use of it.

Interesting. Can you elaborate more on this?

All creatures participate in God's being, which alone is subsistent.

To me, matter in the sense you described it threatens this very claim: matter would imply a basic constituent of material things which comprises them which, in turn, implies fundamental parts that are absolutely simple—they are pure potency infused in some kind of being that will receive the first form—and this would entail that there are multiple purely actual beings. What are you thoughts on that?

This is why I was thinking that composed beings must be infinitely divisible AND infused with being from God; because:

1. If a composed being is finitely divisible, then it’s fundamental part(s) are absolutely simple and two or more absolutely simple beings cannot exist; therefore, since God is absolutely simple every composed being must be infinitely divisible.

2. If composed beings are JUST infinitely divisible (viz., that explains the existence of each), then it wouldn’t exist because no member itself with have subsistent existence; therefore, God must be the first cause of the existence of the infinite chain of divisible parts of a given whole.

What do you think?

EDIT:

I am thinking of the chain of causality for a given object like this:

God → [..., parts of N - 1, parts of N, N]

I don't think it would be possible for:

God → first parts → ... → parts of N - 1 → parts of N → N

It would be impossible because the first parts would have to be absolutely simple because they are not made up of two or more parts: there would be nothing more fundamental to that contributes to the whole (of each first part) that isn't identical to it (viz., there would be no parts). Two or more absolutely simple beings cannot exist because they would be ontologically indistiguishable from each other. Therefore, since God is absolutely simple as subsistent being itself, it follows that this kind of causality would imply the contradiction of having at least two absolutely simple beings (namely God and the first parts).

What do you think?

Yes, and without the form of clay the clay is just fine-grained mineral particles.

Parts are what a material object is composed of. I don't think it makes any sense to talk of the parts of an immaterial form. Neither does your argument make any sense.

How do you define a part?

Again, I defined it as something which contributes to the whole but is not identical to it. Nothing about a part in this sense is restricted to something with tangible parts.

Why not?

Because two ontologically simple things are ontologically indistinguishable from each other.

My dearest condolences! :broken: She will be missed.

You are missing the point.

Even if you accept that there can be a being of pure form, they would have immaterial parts. Parts comprise wholes; and my argument addresses wholes and parts simpliciter.

We can run this argument for something like and Angel that is pure form as well:

1. Either the Angel is comprised of an infinite or finite regression of immaterial parts.

2. A finite regress of immaterial parts entails at least two ultimate parts which are not made up of parts. (For there must be at least one part where the regression ends which by definition has no further parts and there must be two because if there's only one such part then it is identical to the whole which it comprises making it not a part but rather that whole)

3. Two or more beings without parts cannot exist.

4. Therefore, an Angel must be comprised of an infinite regression of parts.

edit: positing a distinction between types or kinds of parts, such as immaterial vs. material parts, does not rejoin my argument here.

Matter, in this sense, is still a constituent in a thing with parts; so either a composed being is composed infinitely or there is a part which is has (somewhere along the line) that has no parts itself.

I apologize: I forgot to respond.

What I don't see here is the alternative they should have chosen, how they could have known that was the better choice and did they have the capability and opportunity to choose it?

This wasn’t an analytic essay: the prose is provocative, pungent, and crude. I think provided explicated life paths would betray that prose.

Who decides whether they are well or sick, according to what criteria?

“The wellness makes them sick; and the sickness makes them well” is a purposeful equivocation for intents of an aphorism. It is supposed to get you thinking about what sense ‘wellness’ and ‘sickness’ are being referred here. How can a person that is well be sick? How can a sick person be well?

What do you think? When would a well person be sick? Or a sick person well? And why would one make the other?

What if most of us are common and content not to walk on flowers, but just look at them alongside the road?

Firstly, it still stampedes authenticity, individual profoundness, and deep thinking; so what you are asking is essentially “what if most of us are content with being inauthentic, dull, and intellectually shallow?”. To that, I say, secondly, that it will be a very shallow sense of happiness: it is not possible to acquire a deep sense of fulfillment that way; and it will tend to come back to haunt those people who are ‘content’ in this way. It’s almost like the short-term happiness makes them well, but also produces long-term misery……..

 If common folk were not a majority, how could they have trod a paved road?

There would be no common folk in the sense you mean if everyone was authentic; unless everyone was authentically the same, which is highly unlikely.

All the people I ever met had thoughts and lives and purposes...But I'm not happier for having chosen differently, and neither their or my lives made an impression on the universe.

Of course most people have purposes and lives—no doubt; however, many people, especially those that are young, walk a path given to them as the easy downstream path of the river of society. It’s so easy to survive and be immanently healthy (physically) following that path nowadays that many people never are slapped with any sort of struggle that forces them to contemplate the heavier, deeper questions in life.

I would say, as a side note, that happiness is not subjective. No, people are not just as happy doing whatever option they choose (out of the full list of options).

What is true meaning and how do you tell it apart from false meaning? What is an authentic self and how can you tell what someone else's authentic self is? What is a 'deeper thing than they're thinking about, and who gets to measure the depth?

Exactly! That’s what the passage that you quoted is trying to get you to think about.

Not always. Mining coal is hard, even if every man in your village does it for want of a better job. Active service in a war is hard, even if all your cohort is conscripted; bearing and feeding nine children is hard, even if every woman on the street accepts all the blessings God sends them.

Most jobs in the west are not like those you mentioned and more and more women are not having kids (or very few). The fact is that most people in the west, such as the US or Europe, have extremely comfortable lives even if they are drowning in debt. Outside of the West, there are plenty of places that have far worse living arrangements (to your point).

Old people have regrets, and some of those regrets are about not having pursued their passion. But they're just as likely to be about doing someone wrong or missing opportunities for happiness. If there are holes, they're particular and personal, not metaphysical.

A regret tends to be the shadow of the right intuition that one did not follow what is good.

Human beings, like sea lions and zebras, are individual, real, particular, unique - not generalities forming a dull backdrop against which the special ones suffer mental anguish and shine like stars.

I didn’t follow this part; but those of us that suffer in the right and proportionate ways for higher goods definitely shine brighter.

When God creates the intelligences (which being intelligences, are immaterial) he is bringing them into being with a certain whatness, through the granting of existence to form (not through generation, the informing of matter, but rather through creation from nothing) but these are not pure being (essence ≠ existence), and so they are subject to change

Again, this treats ‘matter’ as if it is a something that can be created by God to receive a form; and that, whereas, God can also create something which has form without creating this ‘something’ that receives the form.

I am merely asking:

1. What is this ‘something’?
2. How could form be imbued with being without requiring the creation of parts?

For number 1, my answer I have unraveled so far (by merely thinking about it) is that ‘matter’, this ‘something’, is merely that which is capable of receiving form; and only parts are capable of receiving form. So, it follows that the beings which preexist (at least atemporally) the form which is imbued into it are the only beings which can be said to be matter (relative to form). This, of course, leads to the necessary conclusion that composition is infinite and that there is a first cause outside of that infinity for the being of each part (which is God).

For number 2, I find this so far to be metaphysically impossible: Aquinas seems to be blundering by using a notion of some ‘matter’ that is ‘physical’ and trying to omit that for the sake of spiritual substances. However, even these spirits are made up of parts; for otherwise they would be purely actual; and this entails that they have matter in the sense that I defined it in #1.

I am not following why Aquinas is treating ‘matter’ as if it is more than just the potency preexisting beings have to receive form.

What I deny is your premise, that God is absolutely simple.

This isn't a direct counter to my point. If you have finite divisibility, then you will end up with multiple absolutely simple beings (even if they are just 'atoms') and this is impossible. To hold your view, you have to accept that two absolutely simple beings are not ontologically indistinguishable from each other.

Sure, but is existence a form received by an essence?

I would say the existence (being), essence/form, and matter of a thing are all different but related aspects of it. The being is just what makes it real; the form/essence is the universal idea of a thing that makes it the kind of thing it is (viz., provides its whatness); and the matter of a thing is the beings which receive the form through act.

Where it gets weird is that the beings which receive the form have the same setup; namely, they are form received by other beings (which comprise them) through act; and so matter is really just the preexisting being which receives the form ad infinitum.

Of course, if all there is causally is just this infinite regress of composition (of form and matter) then there would be no being; for each member lacks the innate ability to self-subsist (but rather gets it derivatively from another). Therefore, there must be a first cause which is purely actual (viz., self-subsisting being) which provides the being to the infinite regress of composition.

It must be an infinite regress of composition, as opposed to a finite regress, because (1) a finite regress would entail at least two absolutely simple beings (which is impossible) and (2) there would be no matter (since it is just preexisting being which has the potency to receive form).

This also means that God must create the infinite regression of (at least) His immediate creation simultaneously; and this preexistence of matter is merely atemporal.

If existence is a form and an angel receives the form of existence, then the angel must have matter, but I wouldn't really want to describe it that way.

If the form of a thing is its existence, then it can’t have parts; right? There would be nothing to receive the form (i.e., nothing previously which has being to receive it), so a pure form would be a being that is pure idea that self-subsistently exists: isn’t that God? Maybe even God isn’t this kind of being, because God really doesn’t have a form; for He is absolutely simple—we merely talk of Him having a form analogically.

 This also obscures the position which objects to Aquinas and says that angels do have proper (spiritual) matter.

This honestly makes his view even more confusing to me; because I thought he was arguing that Angels are each their own species because they have no matter whatsoever.

Also, how can there be a difference between mental (spiritual) and physical (material) matter? Both are ‘stuff’ that a thing is made up of which can be immaterial insofar as they are not in space or time.

Got it. So, if I am understanding correctly, Aquinas does believe that matter is NOT merely that which is capable of receiving form but also is something physical. If so, then that's fine: I am just using the term matter to refer to that which can receive form simpliciter.

Despite the fact that substance is the individual, which is a composite of matter and form, when you read his Metaphysics, you'll find that Aristotle determines that "substance" is properly assigned to form. This is because n the case of self-subsisting things, the substance of the thing cannot be separated from the thing's form. Therefore the thing's form and the thing's substance are one and the same.

Yes, that is perfectly fine; and does not really deny that substance is comprised of matter and form. It’s an analogical account of God. We say God has a ‘nature’ or ‘essence’ that is identical to His ‘existence’ analogically and not univocally. God doesn’t really have an essence because, as you noted, He is self-subsisting, absolutely unified, Being itself. An essence is tied to the form of a thing, and a form is an actualizing principle which gives the structure to a being; but structure, and this infusion, implies parts. God has no parts, so we speak of His ‘nature’ only as an analogy of comparison to describe Him.

Why do you say this? It is definitely not Aristotelian, as he clearly demonstrates why it s incoherent to assume infinite divisibility of anything substantial.

I am not claiming it is Aristotelian, and I demonstrated it to you here in a former post:

The infinite divisibility of an object is not only possible but necessary. God is the only absolutely simple being (i.e., divine simplicity) and if God is the first member of the causal regress of the composition of an object (which would be the case if the composition is finite in parts) then there would have to be at least one part which is also absolutely simple which is impossible; therefore an objects composition must be equally indivisible and subsistent being of each member is derivative of God as the first cause outside of the infinite regress.

In short, if we have a causal series with God as the beginning for composition like [G, [P1], [P2], [P3], …, O] (where God is ‘G’, the ‘P’s refer to parts, and ‘O’ refers to the object/whole in question), then the immediate subsequent member of the causal chain from God must also be absolutely simple (which in this case is the set of parts containing one element/part, P1); for that part would be composed of either (1) God (which is an absolutely simple being so He would provide no parts to this part, P1) or (2) it’s own self-subsisting being (since nothing comes prior to it that has parts and is not from God). Either way, e.g., the set [P1] contains parts which have no parts. This is impossible because there would, then, be at least two beings that are absolutely simple; and two absolutely simple beings are indistinguishable ontologically. I am pretty sure you would disagree with the idea that ontological simplicity entails one such kind of being (as a possibility); but you get the point.

his is the reason you yourself stated " if each object gets its being from its parts and those parts from its parts ad infinitum then none of them would exist; for none of them have being in-itself".

I did say that, and it does not refer to what you are thinking of. The causality of everything bottoms out at God—e.g., if the set {E} contains everything that is caused, then the set of causality (including what causes, not just what is caused) would be [G, {E}]—but the causality of composition in terms of parts/whole is an infinite set; and this infinite set is identical to {E}. God’s very being is permeated through the infinite collection, which is what accounts for the being of these parts/wholes. As I noted in the quote you have of me, this we can know because an infinite collection of parts and wholes is insufficient to explain how they exist; for each member gets being derivatively from the other and yet no member has the intrinsic ability to be. This means there must be a cause outside of that chain of composition which being is derived from. This is true irregardless if one accepts the infinite divisibility of composition or not.

It does refute your hypothesis. With an infinite amount of time, which is what you allow, that being would necessarily affect and be affected, or else it would be false to say that it is capable of affecting or being affected.

Imagine a block in a room standing still. Imagine the air is removed from the room and you know with 100% certainty nothing will ever infiltrate into the room nor will anything in the room be changed by something in the room. This block, given infinite time, would remain that block in the exact manner it was and will also be.

Fair enough. However, isn't he, then, implying that matter is something which something with parts, in principle, does not necessarily have? If so, then how is this coheren with defining 'matter' as 'that which has the potential to receive form'?

Does Aquinas not think that an Angel's composition is that of recieved form? Namely, a form that is infused with its parts; afterall, the parts of an angel are parts of an angel and not parts of something else (or not parts at all) exactly because they are infused with a form that unifies them into a whole. Right?

Aristotle's Prime Matter (prōtē hulē) is conceived as pure potentiality. Imagine the most basic "stuff" of the universe, utterly undifferentiated and without any inherent qualities, forms, or properties of its own. It's not actually anything specific, but has the potential to become anything (to 'take form', so to speak).

Yes, but then matter, albeit not pure matter in the sense of prime matter, is something separable, in principle, as its own entity. For something which in-itself is pure potential to receive form is toto genere different than that which is actual (viz., has form).

I’ve already noted the non-beingness of prime matter objection; but I will also briefly note that another issue is that prime matter would be absolutely simple and Aristotle equally holds that pure actuality is absolutely simple; but two absolutely simple beings cannot exist because they are ontologically indistinguishable—not merely conceptually or epistemically indistinguishable.

Of course, someone could object that prime matter cannot exist on its own; but, then, there doesn’t seem to be any matter in the sense of being an entity capable of receiving any form—that would be a substance of its own even if it always must be conjoined with something that does not have or has limited potential (like actuality).

For change to occur, there must be something underlying that persists throughout the transformation.

But the annihilation of a substance (as a whole) is done by the actualization of potentials of its parts which are potentials that necessarily annihilate the form it had (thusly disbanding the whole-parts relationship). It seems like Aristotle would reject this and say that the parts of a thing do not have the potential to be actualized in a way that would annihilate its own form (e.g., modifying the parts of a tree by burning it to lose its form of a tree).

Without it, Aristotle argued, things would have to come into being from absolute nothingness, which he rejected as impossible ('nothing comes from nothing').

I agree; but pure actuality actualizing something out of nothing is something I would imagine Aristotle would accept; and this is how the entirety of the infinity of parts and wholes originate—out of nothing from God.

But because prime matter possesses no form or qualities

But if it is pure potentiality; then it has no actuality. Right? So it is non-being. Unless, are you saying actuality is not identical to being?