How Aquinas confuses the First and Second way

[thinkandmull]

On several threads we have gone back and forth on Aquinas’s assertion in the *Summa *that it cann’t be proven from reason that the world isn’t eternal. Now I think it boils down to this: Aquinas attempts to reconcile the First Way with his idea on a potentially eternal world by turning the First Way into the Second Way. Does anybody find this valid? Also, in the *Summa Contra Gentiles *he is quite clear that there CANNOT be an infinity of intermediate motions, but that there must be a first. God as a sustainer of an infinite series is not really a first mover right? Again, the First Way is clear: the sequence of motion cannot extend ad infinitum. Therefore Aquinas clearly contradicts himself in the Summa First Part

God bless

 

[BrotherC]

The first way refers not to a temporal infinity, but a simultaneous infinity. Temporal infinity is possible because the past has no being and future has only potential being. Potential infinity is possible (think of numbers), while actually infinity is not.

St. Thomas’s claim is that everything that is moving is moved by another at simultaneously. There must be something that is not moving and causes the motion of everything else. In motion strictly so called, this need not be God just something immaterial, the way the soul moves the body. In the Summa Contra Gentiles, St. Thomas takes a number of additional steps to move from natural philosophy to metaphysics and show that God must be the prime mover. In the Summa Theologiae he avoids this by using an even more general definition of motion (actualizing potency). This is a metaphysical argument, therefore. Every potency must be actualized in potency, therefore there must be something that is always in act, and this is God.

 

[thinkandmull]

Aquinas doesn’t speak of just one motion moving in between the past and future, moving forward. He speaks of the impossibility of infinite intermediate motions. If motion could have been eternal, that would suffice to explain why there is present motion. There is no need to go from the horizontal to the vertical in speaking of motion alone; so the First Way would be worthless. Second Way doesn’t fit into motion theory, and neither do Leibniz’s arguments on things needing a sufficient reason for their existence. The Second way is correct, but the First Way disproves his theory of a rational eternal universe of motion

 

[Linusthe2nd]

On several threads we have gone back and forth on Aquinas’s assertion in the *Summa *that it cann’t be proven from reason that the world isn’t eternal. Now I think it boils down to this: Aquinas attempts to reconcile the First Way with his idea on a potentially eternal world by turning the First Way into the Second Way. Does anybody find this valid? Also, in the *Summa Contra Gentiles *he is quite clear that there CANNOT be an infinity of intermediate motions, but that there must be a first. God as a sustainer of an infinite series is not really a first mover right? Again, the First Way is clear: the sequence of motion cannot extend ad infinitum. Therefore Aquinas clearly contradicts himself in the Summa First Part

God bless

I doubt that, Thomas knew what he was doing. Of course, according to Aristotle motion was the the cause of change in bodies. At the level of bodies it is the same as an efficient cause. But in Aristotle as in Thomas’ Five Ways the universe, including the earth was eternal and immortal. At the earthly level, the sublunar world, there was not creation, only generation and corruption, local motion, and qualitative change. And in Aristotle, efficient causality is limited to the lowest sphere and the earthly world. Aristotle’s God does not interact with anything below himself. He moves by being loved, as a final cause.

And since Thomas was assuming an eternal world in all the Five Ways, he certainly could be employing efficient causality right on up to the Unmoved Mover, but he does not specfically state it. Though does allow for a God who creates, as an efficient cause, ex nihilo but not in time, it would be an eternal creation.

Linus2nd

 

[balto]

Aquinas doesn’t speak of just one motion moving in between the past and future, moving forward. He speaks of the impossibility of infinite intermediate motions. If motion could have been eternal, that would suffice to explain why there is present motion. There is no need to go from the horizontal to the vertical in speaking of motion alone; so the First Way would be worthless. Second Way doesn’t fit into motion theory, and neither do Leibniz’s arguments on things needing a sufficient reason for their existence. The Second way is correct, but the First Way disproves his theory of a rational eternal universe of motion

Could you provide the relevant passages from the ST or the SCG? It might help so we can figure out what he was trying to say. I don’t know why it would be the case that the Second Way would not fit into the First Way. The Second Way, if I am remembering correctly, deals with arguments from efficient causality. Yet efficient causality is directly related to something actual actualizing a potential in another thing, which ties quite nicely into the First Way. I think eventually the Second Way goes vertical even if it starts going horizontally.

BrotherC is correct that the First Way is concerned with an essentially ordered causal series (simultaneous) and not an accidentally ordered one (temporal). So arguing that the universe is past infinite does not actually address his argument in the First Way, so an eternal universe is irrelevant (although it is probably more correct to call it a “sempiternal” universe rather than an “eternal” one because an eternal universe would not change). What’s unclear to me is what Aquinas means by “intermediate motion” but seeing that he was a brilliant thinker leads me to believe that he would have been aware that he was contradicting himself when he argued that a past-finite universe is something that is held by faith alone.

 

[Richca]

On several threads we have gone back and forth on Aquinas’s assertion in the *Summa *that it cann’t be proven from reason that the world isn’t eternal. Now I think it boils down to this: Aquinas attempts to reconcile the First Way with his idea on a potentially eternal world by turning the First Way into the Second Way. Does anybody find this valid? Also, in the *Summa Contra Gentiles *he is quite clear that there CANNOT be an infinity of intermediate motions, but that there must be a first. God as a sustainer of an infinite series is not really a first mover right? Again, the First Way is clear: the sequence of motion cannot extend ad infinitum. Therefore Aquinas clearly contradicts himself in the Summa First Part

God bless

Aquinas’ first and second proofs for the existence of God as found in the Summa Theologica have nothing to do with either proving that the world had a beginning or that it is eternal. Aristotle himself believed that the world was eternal as well as its motion or change yet he proved that God is the first unmoved mover and the cause of the motion or change in the world.

When Aquinas says in the first and second proofs for the existence of God that you cannot extend a series of movers or efficient causes indefinitely or infinitely, he is not talking about extending the series back in time but in the here and now and at any moment you may be considering the argument.

Aquinas distinguishes between a causal series ordered per se and a causal series ordered per accidens (cf. ST I, Q. 46, Art. 2, reply to obj. 7). A causal series ordered per accidens is linear in character and extends back in time. The causal activity of any particular member of this kind of series is not essentially dependent on any prior member of the series. For example, a son of a father can beget a son of his own and do many other things whether or not his father is living or dead. It is this kind of causal series that it cannot be proven philosophically that it cannot extend back infinitely, for example, that the human species is eternal. However, there may be problems with the human species extending back eternally in time from the natural sciences and of course, from the Holy Scriptures and the catholic faith.

In a causal series ordered per se, the causal activity of any member of the series is essentially dependent on the activity of the first cause. In the first way, Aquinas uses the illustration of a stick being moved by the hand. It is obvious that the motion of the stick is dependent on the motion of the hand. The mover and the thing moved exist simultaneously. It is this kind of series ordered per se which it is impossible to extend back to infinity which Aquinas has in mind in the first and second proofs for the existence of God. God is the first mover as well as the first efficient cause of whatever is moving or changing or causing any movement or change in the world in the here and now and at any moment you may be considering the argument.

 

[thinkandmull]

Aquinas’ first and second proofs for the existence of God as found in the Summa Theologica have nothing to do with either proving that the world had a beginning or that it is eternal. Aristotle himself believed that the world was eternal as well as its motion or change yet he proved that God is the first unmoved mover and the cause of the motion or change in the world.

When Aquinas says in the first and second proofs for the existence of God that you cannot extend a series of movers or efficient causes indefinitely or infinitely, he is not talking about extending the series back in time but in the here and now and at any moment you may be considering the argument.

Aquinas distinguishes between a causal series ordered per se and a causal series ordered per accidens (cf. ST I, Q. 46, Art. 2, reply to obj. 7). A causal series ordered per accidens is linear in character and extends back in time. The causal activity of any particular member of this kind of series is not essentially dependent on any prior member of the series. For example, a son of a father can beget a son of his own and do many other things whether or not his father is living or dead. It is this kind of causal series that it cannot be proven philosophically that it cannot extend back infinitely, for example, that the human species is eternal. However, there may be problems with the human species extending back eternally in time from the natural sciences and of course, from the Holy Scriptures and the catholic faith.

In a causal series ordered per se, the causal activity of any member of the series is essentially dependent on the activity of the first cause. In the first way, Aquinas uses the illustration of a stick being moved by the hand. It is obvious that the motion of the stick is dependent on the motion of the hand. The mover and the thing moved exist simultaneously. It is this kind of series ordered per se which it is impossible to extend back to infinity which Aquinas has in mind in the first and second proofs for the existence of God. God is the first mover as well as the first efficient cause of whatever is moving or changing or causing any movement or change in the world in the here and now and at any moment you may be considering the argument.

You, as well as the others, are missing the point. There is no reason why the casual activity of the infinite series is not enough to explain its existence if you are simply dealing with motion as the force of the argument. The reason one goes to efficient casuality is a totally different argument, which is why there is both a First Way AND a Second way. Why do you think it is rational that he would make the same argument twice in an attempt to give reasons which you can count on your fingers? There is no reason why an infinite series couldn’t be like an animal, moving with its own efficient life-like casuality like evolutionalists believe. And Aquinas specifically says there canNOT be infinite intermediate causes. Its that simple. He was torn between the two beliefs and had a bad philosophical day, and probably a headache…

Aquinas even admits that it is easier to see the truth about the existence of God if you believe that the world had a beginning. I believe it is something obvious to humans that the world had a beginning, and it is highly unnatural to try to imagine it as if it were eternal. If you assume the eternity of the world, how do you know that God can create something out of nothing? He can’t make a round triangle. How can he make something from nothing? If we allow our reason to accept common sense and say that time began, than the truth of creation from nothing forces itself upon us. (It is not true to say “from nothing nothing comes” because God is supreme over that. It is better to say that BECAUSE of nothing, nothing comes)

And Linus, eternal creation ex nihilo is a contradiction in terms. It would be creation which needed God to exist, but it never was nothing so it couldn’t be “from nothing”.

 

[thinkandmull]

newadvent.org/summa/1046.htm#article2

 

[thinkandmull]

**Reply to Objection 7. In efficient causes it is impossible to proceed to infinity “per se”–thus, there cannot be an infinite number of causes that are “per se” required for a certain effect; for instance, that a stone be moved by a stick, the stick by the hand, and so on to infinity. But it is not impossible to proceed to infinity “accidentally” as regards efficient causes; for instance, if all the causes thus infinitely multiplied should have the order of only one cause, their multiplication being accidental, as an artificer acts by means of many hammers accidentally, because one after the other may be broken. It is accidental, therefore, that one particular hammer acts after the action of another; and likewise it is accidental to this particular man as generator to be generated by another man; for he generates as a man, and not as the son of another man. For all men generating hold one grade in efficient causes–viz. the grade of a particular generator. Hence it is not impossible for a man to be generated by man to infinity; but such a thing would be impossible if the generation of this man depended upon this man, and on an elementary body, and on the sun, and so on to infinity. **

This is utter nonsense. The generation of a man DOES depend on the father, and him on his father, ect ect ect.

 

[Linusthe2nd]

You, as well as the others, are missing the point. There is no reason why the casual activity of the infinite series is not enough to explain its existence if you are simply dealing with motion as the force of the argument. The reason one goes to efficient casuality is a totally different argument, which is why there is both a First Way AND a Second way. Why do you think it is rational that he would make the same argument twice in an attempt to give reasons which you can count on your fingers? There is no reason why an infinite series couldn’t be like an animal, moving with its own efficient life-like casuality like evolutionalists believe. And Aquinas specifically says there canNOT be infinite intermediate causes. Its that simple. He was torn between the two beliefs and had a bad philosophical day, and probably a headache…

Aquinas even admits that it is easier to see the truth about the existence of God if you believe that the world had a beginning. I believe it is something obvious to humans that the world had a beginning, and it is highly unnatural to try to imagine it as if it were eternal. If you assume the eternity of the world, how do you know that God can create something out of nothing? He can’t make a round triangle. How can he make something from nothing? If we allow our reason to accept common sense and say that time began, than the truth of creation from nothing forces itself upon us. (It is not true to say “from nothing nothing comes” because God is supreme over that. It is better to say that BECAUSE of nothing, nothing comes)

And Linus, eternal creation ex nihilo is a contradiction in terms. It would be creation which needed God to exist, but it never was nothing so it couldn’t be “from nothing”.

Read the following link where Thomas explains that, philosophically, an eternal universe is not contrary to reason. dhspriory.org/thomas/english/DeEternitateMundi.htm

Linus2nd

 

[thinkandmull]

I still disagree with him. Believing time is eternal distorts time itself and is nonsensical. And there is no way out of the fact that he said there can’t be infinite intermediate causes in the Summa Contra Gentiles

 

[thinkandmull]

And St. Bonaventure wrote a thesis in which he refuted Aquinas’s point of view

 

[thinkandmull]

In DE AETERNITATE MUNDI He says that “Augustine offers many arguments against the eternity of the world in XI and XII De Civitate Dei”, which the context makes clear are probable arguments at best, but nontheless arguments by Augustine ye. At the end of the thesis he says that the weak arguments for the non-eternity of the world gives probability to the belief that the world is eternal. So we have Augustine vs Aquinas. Who do you think was wiser?

 

[thinkandmull]

Finally, Aquinas says “Nevertheless, certain great men have piously maintained that God can make past events not to have happened, and this was not reputed to be heretical.” So great men make huge mistakes, those who said God can do the impossible, and those who try to ambiguously defend them by saying they ain’t heretical

 

[Linusthe2nd]

Finally, Aquinas says “Nevertheless, certain great men have piously maintained that God can make past events not to have happened, and this was not reputed to be heretical.” So great men make huge mistakes, those who said God can do the impossible, and those who try to ambiguously defend them by saying they ain’t heretical

Again, we have " De Potentia, Question 3, Article V " which, according to Thomas, that if the world is eternal, it still owes its existence to God, which would be a an eternal creation, but not in time. And Thomas thinks this is not contrary to faith. Thus Thomas says, " .The third argument is based on the principle that whatsoever is through another is to be reduced to that which is of itself. Wherefore if there were a per se heat, it would be the cause of all hot things, that have heat by way of participation. Now there is a being that is its own being: and this follows from the fact that there must needs be a being that is pure act and wherein there is no composition. Hence from that one being all other beings that are not their own being, but have being by participation, must needs proceed. This is the argument of Avicenna (in Metaph. viii, 6; ix, 8). Thus reason proves and faith holds that all things are created by God, "

I also refer you to my thread, " Eternal Creation Ex Nihilo vs Modern. " of course this is all speculation. It just shows that if the world is eternal, Thomas still insisted on an eternal creation. Although I disagree with him that Aristotle held this position. It is merely the way Thomas interpreted one paragraph he cited in De Potentia, Question 3, Article 5.

Linus2nd.

 

[balto]

**Reply to Objection 7. In efficient causes it is impossible to proceed to infinity “per se”–thus, there cannot be an infinite number of causes that are “per se” required for a certain effect; for instance, that a stone be moved by a stick, the stick by the hand, and so on to infinity. But it is not impossible to proceed to infinity “accidentally” as regards efficient causes; for instance, if all the causes thus infinitely multiplied should have the order of only one cause, their multiplication being accidental, as an artificer acts by means of many hammers accidentally, because one after the other may be broken. It is accidental, therefore, that one particular hammer acts after the action of another; and likewise it is accidental to this particular man as generator to be generated by another man; for he generates as a man, and not as the son of another man. For all men generating hold one grade in efficient causes–viz. the grade of a particular generator. Hence it is not impossible for a man to be generated by man to infinity; but such a thing would be impossible if the generation of this man depended upon this man, and on an elementary body, and on the sun, and so on to infinity. **

This is utter nonsense. The generation of a man DOES depend on the father, and him on his father, ect ect ect.

I read the article you linked to and I still am not seeing the term “intermediate cause” so I still am unclear what you are referring to.

This passage that you quoted vindicates what people have been saying to you. Your last statement is indicative of the difficulty you are having. The generation of a man does not depend on the father in an essentially ordered causal series. If my father goes out of existence, do I go out of existence? No, so my existence is in no way dependent on his current action. On the other hand, my existence does depend here and now on the forces keeping my atoms together because if those forces ceased to exist I would no longer exist either.

The problem you are having is that you are tying temporal separation to efficient causality, when there is no necessary connection between the two. Yes, my father’s actions in the past initiated a process that led to my generation, and that is a type of efficient causation; that is an accidentally ordered series. But there is another kind of efficient causation that is simultaneous with the effect, for instance the shape of the hands of a potter molding clay into a certain shape, to borrow an example used on CAF frequently. The simultaneous efficient causation is the type that Aquinas argues cannot proceed to infinity. Assuming that efficient causation requires temporal separation leads to all the nightmarish Humean causation puzzles that plague most of modernity.

 

[balto]

You, as well as the others, are missing the point. There is no reason why the casual activity of the infinite series is not enough to explain its existence if you are simply dealing with motion as the force of the argument.

False, an infinite series cannot explain motion (keeping in mind that “motion” in this context refers to “change”). Everything we know of changes only because some other agent actualizes one of its potentialities. If you have an infinite series of motion, you never have a purely actual entity that can effect change without being moved itself. Such an infinite series does not explain the motion of anything in the series because nothing in the series has the inherent power of unmoved motion. It would be like seeing a series of train boxcars moving on frictioned rails (to avoid all the modern Newtonian misconceptions) and thinking it logical to suppose that an infinite series of boxcars would explain the motion. None of the boxcars have the inherent power of acceleration so supposing there are an infinite number of boxcars explains nothing.

There is no reason why an infinite series couldn’t be like an animal, moving with its own efficient life-like casuality like evolutionalists believe. And Aquinas specifically says there canNOT be infinite intermediate causes. Its that simple. He was torn between the two beliefs and had a bad philosophical day, and probably a headache…

No, there isn’t any reason why such a series cannot exist, because it is an accidentally ordered one, which is why Aquinas specifically says that it is only known by faith alone that the universe is past finite. I’m not sure why you think he said otherwise because he specifically defended his view in article 2 of the linked source.

Aquinas even admits that it is easier to see the truth about the existence of God if you believe that the world had a beginning. I believe it is something obvious to humans that the world had a beginning, and it is highly unnatural to try to imagine it as if it were eternal. If you assume the eternity of the world, how do you know that God can create something out of nothing? He can’t make a round triangle. How can he make something from nothing? If we allow our reason to accept common sense and say that time began, than the truth of creation from nothing forces itself upon us. (It is not true to say “from nothing nothing comes” because God is supreme over that. It is better to say that BECAUSE of nothing, nothing comes)

You’re equivocating on God’s eternality here. I suspect you are thinking that God being eternal means that He exists in some infinite timeline that supersedes our own, which coincides with our own finite timeline. That is called “sempiternality” and it is the wrong way to think about God’s eternality. Eternal means that God is “out of time” and does not change. It is not the case that there was [God] for an infinite amount of time and then voila, He causes the universe to exist at some point and now there’s [God, universe]. Even if the universe is past finite, it is still impossible to identify a time at which God existed and the universe did not.

And Linus, eternal creation ex nihilo is a contradiction in terms. It would be creation which needed God to exist, but it never was nothing so it couldn’t be “from nothing”.

Eternal creation is certainly possible, and Aquinas gave an example of such a universe in his reply to objection 1 in article 2 when he talks about the footprint. Here’s another one: God creates a universe with a single blue ball in it that never changes in anyway. The universe is eternal, but it still depends on God’s sustaining creative act since the essence of a blue ball does not include its existence (it is a contingent thing) so the essence’s potential for existing still needs to be eternally actualized by God.

 

[balto]

I still disagree with him. Believing time is eternal distorts time itself and is nonsensical. And there is no way out of the fact that he said there can’t be infinite intermediate causes in the Summa Contra Gentiles

Can you provide the passage from the SCG where he discusses intermediate causes?

Yes, believing time is eternal is nonsense because the two terms are mutually exclusive. Eternal means “out of time” so believing time is eternal amounts to believing that time is outside of time. When he speaks of an eternal universe, he is thinking of a sempiternal universe, with which time is consistent, and he makes this clear in his reply to objection 5 in article 2:
St. Thomas Aquinas:

Reply to Objection 5. Even supposing that the world always was, it would not be equal to God in eternity, as Boethius says (De Consol. v, 6); because the divine Being is all being simultaneously without succession; but with the world it is otherwise.

The divine Being is all being simultaneously without succession (i.e. eternal), but with the world it is otherwise (i.e. sempiternal, because it has succession and experiences change). That’s not to say you couldn’t have an eternal universe as I said previously, but a truly eternal universe is not what people have in mind when they say the universe is past-infinite.

 

[thinkandmull]

I didn’t separate sempiternal from eternal, but that doesn’t change my arguments: Going vertical is the second way, not the first way.

Now let us examine the Summa Contra Gentilies First Part.

[6] **On the basis of these suppositions Aristotle argues as follows. That which is held to be moved by itself is primarily moved. Hence, when one of its parts is at rest, the whole is then at rest. For if, while one part was at rest, another part in it were moved, then the whole itself would not be primarily moved; it would be that part in it which is moved while another part is at rest. But nothing that is at rest because something else is at rest is moved by itself; for that being whose rest follows upon the rest of another must have its motion follow upon the motion of another. It is thus not moved by itself. Therefore, that which was posited as being moved by itself is not moved by itself. Consequently, everything that is moved must be moved by another. **

The animal is moved by the soul, which uses the legs, two at a time, to move. The two other legs are at rest while the others move. There is no reason to assume that motion doesn’t explain itself.

[8] In the second way, Aristotle proves the proposition by induction [Physics VIII, 4]. Whatever is moved by accident is not moved by itself, since it is moved upon the motion of another. So, too, as is evident, what is moved by violence is not moved by itself. Nor are those beings moved by themselves that are moved by their nature as being moved from within; such is the case with animals, which evidently are moved by the soul. Nor, again, is this true of those beings, such as heavy and light bodies, which are moved through nature. For such beings are moved by the generating cause and the cause removing impediments. Now, whatever is moved is moved through itself or by accident. If it is moved through itself, then it is moved either violently or by nature; if by nature, then either through itself, as the animal, or not through itself, as heavy and light bodies. Therefore, everything that is moved is moved by another.

See, he contradicts himself: “what is moved by violence is not moved by itself… If it is moved through itself, then it is moved either violently or by nature.” He says animals move themselves, but that “everything that is moved is moved by another”.

[12] The first is as follows [VII, 1]. If among movers and things moved we proceed to infinity, all these infinite beings must be bodies. For whatever is moved is divisible and a body, as is proved in the Physics [VI, 4]. But every body that moves some thing moved is itself moved while moving it. Therefore, all these infinites are moved together while one of them is moved. But one of them, being finite, is moved in a finite time. Therefore, all those infinites are moved in a finite time. This, however, is impossible. It is, therefore, impossible that among movers and things moved one can proceed to infinity.

No, it is moved in eternal time. If he believes an eternal world is possible, wouldn’t eternal time be a necessary factor?

[14] The second argument proving the same conclusion is the following. In an ordered series of movers and things moved (this is a series in which one is moved by another according to an order), it is necessarily the fact that, when the first mover is removed or ceases to move, no other mover will move or be moved. For the first mover is the cause of motion for all the others. But, if there are movers and things moved following an order to infinity, there will be no first mover, but all would be as intermediate movers. Therefore, none of the others will be able to be moved, and thus nothing in the world will be moved.

That is the first way, and it contradicts an eternal world. It doesn’t surprise me that he contradicts himself. I am reading Kant’s Critique of Pure Reason and he contradicts himself. It is not uncommon for philosophers to contradict themselves. Philosophy is deep

 

[Richca]

**Reply to Objection 7. In efficient causes it is impossible to proceed to infinity “per se”–thus, there cannot be an infinite number of causes that are “per se” required for a certain effect; for instance, that a stone be moved by a stick, the stick by the hand, and so on to infinity. But it is not impossible to proceed to infinity “accidentally” as regards efficient causes; for instance, if all the causes thus infinitely multiplied should have the order of only one cause, their multiplication being accidental, as an artificer acts by means of many hammers accidentally, because one after the other may be broken. It is accidental, therefore, that one particular hammer acts after the action of another; and likewise it is accidental to this particular man as generator to be generated by another man; for he generates as a man, and not as the son of another man. For all men generating hold one grade in efficient causes–viz. the grade of a particular generator. Hence it is not impossible for a man to be generated by man to infinity; but such a thing would be impossible if the generation of this man depended upon this man, and on an elementary body, and on the sun, and so on to infinity. **

This is utter nonsense. The generation of a man DOES depend on the father, and him on his father, ect ect ect.

Again, you are confusing as other posters have pointed out in later posts between an order of efficient causes per se acting together at the same time or simultaneously and an order of efficient causes per accidens which are non-simultaneous acting causes. In the first and second proofs for the existence of God in Aquinas’s Summa Theologica, Aquinas is talking about an order of movers and efficient causes per se and the eternity or non-eternity of the world is irrelevant which is why he makes no mention of it. Even if the world was eternal, it would require a first mover and a first efficient cause.

You seem to have a problem that a first mover or first efficient cause requires of necessity that it be prior in time to whatever it is moving or causing but this is not necessarily so. It only need be prior in nature. Since God’s will is the cause of things and His will is eternal, He could have produced an eternal effect if he had so willed it. However, we believe that from all eternity God did not will that the world should be eternal and as Aquinas says it shows more the power of God and that God is the cause of the world as there are religions even today who confuse the existence of the world with God.

In the catholic faith in the Trinity, we believe that the Father is the origin or the principle without a principle of the Trinity. The Son is from the Father and the Holy Spirit is from the Father and Son. Yet, the Father is not prior in time to the Son nor are the Father and Son prior in time to the Holy Spirit. For all three persons of the Trinity are eternal.