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12/19/2017 2:34 pm  #1

Are generation and corruption "motions" in A-T?

 People who are interested in the scope of what St. Thomas understood by motion are invited to contribute to this thread. I don't think its impact on the First Way is big, but this subtopic gets at what Aquinas may have had in mind by "motion" there.

On SDP's thread, I said that in Aristotle's mature formulations, and in Aquinas' considered applications of Aristotle's physics, "motion" is actualization of a potency, and thus, a change, with respect to a substance's location, quality/ies, or magnitude. The latter changes amount to growth and decay, which are changes in a thing's size and sometimes other associated properties (e.g. how much hair I have, heh heh). I cited passages in his presumably earlier works where Aristotle names generation and corruption as well among motions, but I maintained that we do justice to Aristotle if we go with passages where he provides argument on the point. Esp. in Physics V and VIII, Aristotle gives arguments for excluding generation and corrupltion from among motions, "kineseis," although he considers them changes, "metabolai." 

I also cited Aquinas' discussions of the scope of "motion" in his commentary on the Physics. Aquinas was well aware of Aristotle's change of language, and he pointed out that Physics V through VIII treat motion in a strict sense as locomotion, alteration, and growth/decay and not as gen/corr.

Some other members of this forum disagreed, allowing that generation and corruption are motions in Aquinas' eyes, at least when he argues for God from motion. Jeremy Taylor cited some secondary sources, including Garrigou-LaGrange, for the thesis that Aquinas defines motion more broadly, i.e. as any case where something in actuality brings something else from potency to actuality in a certain respect, including in its substance. On this view, something's transition from being potentially man to being actually a man counts as motion as much as does his transition from being, say, sick to healthy.

Does this question have relevance beyond the history of the Aquinas' thought? Well, some. First, a defender of the First Way might grant that uniform rectilinear motion is not change but might seek to save the First Way by instancing other kinds of changes as requiring actualized movers, all the way up to the UM. If changes in substance count as motions, then the defender of the First Way gains more kinds of change for which to say that a string of actualizers, up to the UM, is necessary. Second, Edward Feser and others argue that the First Way entails refutation of the principle of Existential Inertia. I'm not clear right now whether generation corruption are tied to the claim that substances necessarily must be sustained by the UM in existence once they exist, but there may be a tie.

If generation and corruption, on the other hand, don't count as motions, defenders of the First Way can still argue from alteration and growth/decay to the need for a UM, whatever they do with local motion (I don't go into views of physicists in this thread.) So the relevance of the present thread to controversies over the soundness of the First (and Second) Way may be limited.

In any case, I find puzzles within a philosopher's work to be fruitful springboards for further study. FWIW here is what I've come up with so far. I maintain my view that on the whole, Aquinas does NOT include generation and corruption among "motions."

In addition to passages I've cited (I'll paste them in later), consider this from his discussion of Christ's generation, from In III Sent. d. 3, q.5 a.2 ad 4. Enlisting Ari's Physics VIII and VI, Aquinas writes, "between any two instance of time there is an intervening time, as is proved in Physics VI. Based on that, it is not possible to accept that there is an instant in which that which is becoming white is not white. And it is similar in the case of changes (mutationibus) which, although they are not motions, nevertheless follow upon some motion; just as generation follows alteration, and illumination follows the local motion of the sun ... I say therefore, that the conception of Christ, although it is not motion, since it does not have succession, nevertheless is joined/connected to a certain local motion, at least to the local motion of the material of blood to the place of generation, where it [sc. blood] came together from all sides."

Here we see, not only that Aquinas speaks of generation as a change that is not motion, but also that he considers the local motion of something to be a necessary precondition for it. That's another topic discussed in the SDP thread, where I offered passages from Aristotle and Aquinas in which the primacy of local motion is traced to the necessity that some constituent of a thing change its position in the thing in order for alteration or growth/decay to occur, let alone for generation/corruption to occur.

I note also that at the time he wrote this part of his commentary on the Sentences of Peter Lombard, Aquinas was well acquainted with the doctrine of the latter part of the Physics, in which Aristotle explicitly argues against including generation and corruption among motions/kineseis.

 In a second box I'll put some notes I've taken from Aristotle in the past about why motion does not include gen/corr. In a third, I shall put some passages where Aquinas says that generation or corruption are not motions. I shall put the important sentence from the First Way in a later box. Jeremy Taylor and I both thought of it around the same time on the SDP thread. That sentences raises the question, does Aquinas broaden the scope of "motion" in the First Way beyond the strict sense that he takes from the mature Aristotle to employ in other parts of his work? 

Last edited by ficino (12/19/2017 3:48 pm)


12/19/2017 2:40 pm  #2

Re: Are generation and corruption "motions" in A-T?

Here is a second box with some notes on Aristotle's reasons for denying that generation and corruption are kineseis, "motions."

Aristotle says that motion is one of the things that are continuous, Phys III.1, 200b17. It requires place and void and time. Those things are common to all things and are universal. Then he says there is something in entelechy only, and something else in both potentiality and entelechy, the one a “this,” the other how big or what sort and the same of the other categories of being. and of relation. The one is spoken of according to excess and defect, the other acc to productive (poihtikon) and undering (pathhtikon), and in general, such as to move and such as to be moved (which are reciprocal). There is no motion besides of things, for there is always something changing in being (ousian) or size or quality or place, and there is nothing common which isn’t one of the predications… so that there are as many species of motion and change as are of being, Phys III.1, 200b26-201a9. 
        Starting from Physics V, though, the entities that undergo motion are limited to quantity, quality and place, because 1) substance has no contrary, and generation and corruption are not motions, since there is no substance in actuality and there can’t be motion of what only exists potentially; 2) motion is not in the category of relation, for one correlative may change and not the other; 3) not agent and patient, since what is changing is not from one action to another or one passion to another, since there is no motion of motion or becoming of becoming or change of change, else infinite regress. It is rather a substance that changes in size, location or quality. Aristotle leaves accidental change out of account, and there can be accidental motion in other categories. Phys V.1-2, 225a12-226a22.Three kinds of motion, only in the genera of quality, quantity and place: V.2. Since becoming and perishing imply contradiction and are not motions, only change by one subject on another is motion. Every changing subject is a contrary, incl. privation, or an intermediate. So since motion is denominated by its terminus, there are only three kinds of motion: of quality, of quantity, and of place. Not according to substance, because substance has no contrary. Not of relation, since the correlative may not change, so the motion would be accidental. Not in respect of agent and patient or mover and moved, because there cannot be motion of motion or change of change (he goes into args about this). There has to be matter underlying all processes of becoming and changing, so no change of change. Motion in respect of quality is alteration, includes both contraries; of quantity is increase or decrease; place is locomotion. “At rest” applies only to something not moving but capable of it, for that which primarily moves locally and corporeally, the things moved and their movers must be continuous or in contact with one another so that they all form a unity, Phys. 242b. CF. De Caelo IV.3, where “three motions”, sc. in size, quality, place, 310a23-24, are reworded, 310b22.

Last edited by ficino (12/19/2017 2:55 pm)

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12/19/2017 3:18 pm  #3

Re: Are generation and corruption "motions" in A-T?

Some other passages where Aquinas says that generation and corruption are not motions:

SCG II.89.6: on the theory that full human soul is virtually contained in seed, "It would further follow both that the substantial form would be brought from potency to act, not all at once but in successive stages, and that generation is a continuous motion, just as alteration is. Now, all these consequences are impossible in nature." [tr. from dhspriory modified]

[from #64 on the SDP thread} In his commentary on Aristotle's Physics, Aquinas distinguishes between Aristotle's discussions of motion in a strict sense in Book V and later, where Ari limits motion to locomotion, alteration and growth/decay, and Ari's use of a more common sense of "motion" in Book III, where Ari speaks of it as an alternative of "change/mutation," as though it can include generation and corruption (In Phys. III l. 2, C286). In other places in Aquinas' commentary, where Aristotle restricts motion to the three above species, Aquinas notes those three as motion in the strict sense. John Wippel, 
The Metaphysical Thought of Thomas Aquinas (Cath U Press 2000), 445-6 wonders whether Aquinas uses the term "motion" in this broad sense in the First Way, so as to include generation and corruption. Wippel comes down to this: "I am inclined to limit motion as it appears as the starting point of the first way to some form of motion taken strictly, but to suggest that in the course of justifying the principle of motion -- whatever is moved is moved by something else -- Thomas uses motion broadly enough to apply to any reduction from potentiality to actuality." Wippel thinks Aquinas may have allowed a similar, broader understanding of motion in SCG I.13. Then Wippel concludes, "Nonetheless, the starting point for both of these arguments appears to be motion taken strictly and, to be specific, local motion. Perhaps it is because the first way in the Summa theologiae begins with readily observable phenomena--local motion and alteration--that Thomas describes it as the 'more manifest way'."

I believe Wippel's conclusion is correct. 1) In SCG I.13, Aquinas refers expressly and often in those arguments to Books VII and VIII of the Physics. By the time Aristotle wrote the second half of the Physics, he had excluded generation and corruption from motions. It's that second half of the Physics that Aquinas applies in his proofs from motion.
 2) The A-T presentation of motion gives it a telos, an end. If the substance passes out of existence, it is not in entelechy, fulfillment, which is supposed to be the state that a thing attains when it attains an end. 

[from #73 on SDP thread]
 In his proofs from motion, Aquinas employs Aristotle's expositions from this latter part of the Physics, where Aristotle had limited motion to locomotion, alteration, and growth/decay. Check Aquinas' frequent references to the Physics in SCG I.13. There, in arguments from motion, Aquinas does not employ passages from earlier books of the Physics or from other early works of Aristotle in which generation and decay are listed among motions. In his arguments from motion, Aquinas cites from Aristotle's Physics only bks. VI-VIII, where motion (kinesis) is limited to locomotion, alteration, and growth/decay.
[from #89]
Cf. lectiones 2-4 of his commentary on Physics Book V. Aquinas goes into a lot of detail explaining how Aristotle restricts kinesis or motus to changes in location, quality or quantity and how Ari denies that changes in substance are species of kinesis. Aquinas explains that Aristotle in bk V makes motus a species of mutatio.

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12/19/2017 3:44 pm  #4

Re: Are generation and corruption "motions" in A-T?

Does Aquinas employ a wider sense of "motion" in the First Way than in some places where he adheres more strictly to the later Aristotle? Does Aquinas allow ANY actualization of a potency to be a motion?

In the First Way, the premises include this:
"For to move is nothing other than to bring something out from potency into act..." If generation is bringing an entity in potency to be an entity in actuality, is that change a species of motion?

Like John Wippel (cf. #3 above), I think the answer is no, but I don't think this can be proved with certainty. That's because Aquinas here does not make explicit whether he means, "if it's A it's B" to entail the converse, "if it's B it's A." B may have a wider scope than A.

Aquinas uses "nothing other than" locutions very often. Maybe someone has done a study of them. From what I've looked at, as one might suspect, no obvious answer about this premise of the First Way emerges from Thomas' word usage. We get places where "A is nothing other than B" implies the converse, and other places where this expression does not imply the converse. 

E.g. SCG III.97.3: "form is nothing other than a divine likeness that is participated in things."  It does not seem that every divine likeness participated in by things is a form, since creatures participate in existence and goodness, but those are transcendentals, not genera and thus, not forms.

SCG I.98.2 "for to be alive is nothing other than to be such and such a thing proceeding from such and such a form." But not every thing that is such by virtue of a formal cause is alive.

And so on. Citations can be multiplied.

So since Aquinas' language does not make it explicit in the First Way that every case of actualization is a motion, and since such a doctrine conflicts with other things Aquinas accepts from the mature Aristotle about motion, ANd since his examples in the First Way are not of substantial change, I think prudence counsels against reading changes of substance into the set of "motions" in view in the First Way.

Last edited by ficino (12/19/2017 5:55 pm)

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12/19/2017 4:02 pm  #5

Re: Are generation and corruption "motions" in A-T?

It seems to me that even if that doesn't make it explicit it provides ample reason to consider motion broadly enough as to include it. So I don't see how it leads to the answer as No. And secondly even if we accept from above that act/potency has wider scope than "motion" it hardly follows from it that argument can't be formulated in terms of that.


12/19/2017 4:39 pm  #6

Re: Are generation and corruption "motions" in A-T?

The first way may begin with motions we observe in our everyday lives, whether or not these include generation and corruption, but it then moves to the general concepts of act and potency. Generation and corruption are an example of the actualisation of potency, and it certainly isn't a case, for Aquinas, of potency acutalising itself. So I'm not really sure this issue, even if Ficino is correct, is very important to the first way. 


12/20/2017 2:16 pm  #7

Re: Are generation and corruption "motions" in A-T?

@ Calhoun and Jeremy, I understand what is being done in proofs that seek to argue from change as actualization of a potency by something else in act. And I understand that someone may seek to reconstruct the First Way so as to include changes in substance, as Feser and others have so reconstructed it.

Thomas' own meaning in the First Way is at the least of importance for the history of philosophy. So the question matters for attempting to understand his thought. The question may also be important for the soundness of the argument if there are problems with explaining generation and corruption as outcomes of hierarchical series ordered per se. I haven't thought that through.

Back to the interpretation of Thomas: not all will be interested in more historical questions, and that's fine. For those who are: the more I poke into this, the more I am convinced that we do not have grounds for supposing that he means "motion" in his First Way to include generation and corruption. 

I've mentioned his commentary on the Physics before and quoted pieces. Some longer quotations are below the dotted line below, for those who have time to read them. As I've said, Aquinas accepts Aristotle's restriction of motion to locomotion, alteration, and growth/decay, and he even offers supporting arguments in C663-664. He cites these latter books of the Physics often in his arguments from motion in SCG and ST.

Consider as well:
1. Aquinas' examples of motion in the First Way and in SCG I.13 do not include generation and corruption of substances. They only include locomotion, alteration, or growth/decay.
2. In SCG I.13.19, Aquinas says that the species and genera of motion are finite in number, and he enumerates the three standard species without mentioning gen/corr: "If, however, the mover is moved by another species of motion, so that (namely) the altering cause is moved according to place, and the cause moving according to place is increased, and so forth, since the genera and species of motion are finite in number, it will follow that we cannot proceed to infinity. There will thus be a first mover, which is not moved by another. Will someone say that there will be a recurrence, so that when all the genera and species of motion have been completed the series will be repeated and return to the first motion? This would involve saying, for example, that a mover according to place would be altered, the altering cause would be increased, and the increasing cause would be moved according to place." It seems strange that, if he wanted 'motion' to include generation/corruption, he should leave them out just here.

So there is considerable reason to suppose Aquinas thinks of "motion" under Aristotle's mature formulation, since he knew that formulation well by the time he wrote the SCG and ST. The texts supply no positive reason to suppose he is including them. 


In his Commentary on Aristotle’s Physics V.2, Aq makes clear that Ari is now using “motion” with a scope restricted to locomotion, alteration and growth/decay, excluding generation and corruption. Those are mutationes but not motus.
  C649 “… when Aristotle defined motion above in Book III, he took the word ‘motion’ as common to all the species of mutation. Here he attributes this meaning to the word ‘mutation.’ And he uses ‘motion’ in a more limited sense as a certain species of mutation.”… C652 there cannot be a species of mutation from non-subject to non-subject. Every mutation is between opposites, but two negations are not opposites; they can be simultaneously true of one and the same thing, as a stone is not sick and not healthy. Mutation per se is only between contraries and contradictories; mutation from negation to negation is only per accidens. C656 “… he shows that neither of the foregoing [sc. generation and corruption, discussed in C654-655] is motion.
   First he shows that generation is not motion, and secondly that corruption is not motion, where he says, ‘So, too, perishing…’
   He proves the first point with two arguments. The first is as follows. That which is simply not a ‘this’ cannot be moved, For that which is not is not moved. But that which is generated simply is not a ‘this’; for it is simply non-being. Therefore, that which is generated simply is not moved. Therefore simple generation is not motion…”
  C657 “He gives the second argument where he says, ‘… and it may be further…’ The argument is as follows.
     Whatever is moved is in place. But that which is not is not in place, because it can be said to be anywhere. Therefore that which is not is not moved. This is the same conclusion as the above. The truth of the first proposition arises from the fact that, since local motion is the first motion, it is necessary that whatever is moved be moved with respect to place, and thus is in place. And when that which is prior is removed, things which are consequent are also removed.
   C658 Next where he says, ‘So, too, perishing …’, he proves that corruption is not motion. Nothing is contrary to motion except motion or rest. But generation, which is neither motion nor rest, as was shown, is contrary to corruption. Therefore corruption is not motion.
  C659 Next where he says, ‘Since, then, every motion …’ he concludes from the above that motion is the remaining part of the division given above.
  Motion is a certain species of mutation because is motion there is something after another, which he said above pertains to the nature [ratio] of mutation. But motion is neither generation nor corruption, which are mutations in respect to contradictories. And since there are only three species of mutation, it follows of necessity that motion is mutation from subject to subject.”
In Arist. Phys. V.3 continues the above. C662 “He proves as follows that there is no motion in the genus of substance. Every motion is between contraries, as was said above. But there is no contrary of substance. Therefore there is no motion in respect to substance.” C663 Aq discusses places in Ari (GC II.3, 331a2-6; Caelo I.3, 270a13-23) that create difficulty: where a substance is said to be the contrary of another substance (GC), sc. fire to water; where heavens are not generable or corruptible because they have no contrary (Caelo). C664 The answer is that forms of diverse species can differ from each other w/ respect to excess and defect but not w/ respect to their own proper natures [ratio]. So there need not be a passage in order through intermediaries between one substantial form and another. “Hence Aristotle’s proof that there is no motion in substance because there is no contrariety in substance is demonstrative, and not just a probable argument, as the Commentator seems to indicate. Moreover, that there is no motion in substance can also be proved by means of another argument which he gave above, namely, the subject of substantial form is being in potency only.” [from the Blackwell, Spath, Thirlkel translation]

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12/20/2017 5:13 pm  #8

Re: Are generation and corruption "motions" in A-T?

How could there be problems if generation and corruption are the actualisation of potency?


12/21/2017 9:49 pm  #9

Re: Are generation and corruption "motions" in A-T?


From Aquinas's 


1. As the Philosopher says in On the Soul III, the sciences are divided off in the same manner as things are — for all habits are distinguished by their objects, from which they are specified. Now the things considered by Natural Science are motion and mobile being. Thus the Philosopher says in Physics II that whatever things move, they themselves being moved, these belong to physical speculation. Consequently, it is according to the differences between motions and mobiles that the parts of natural science must be distinguished and ordered.

Now the first motion is local motion, which is more perfect than the other kinds, and common to all natural bodies, as is proved in Physics VII. Therefore, after the study of motions and mobiles in common in the book of the Physics, it was first necessary to treat of bodies as they are moved with local motion. This was in the book On the Heavens, which is the second book of natural science. What remains, therefore, is to consider the other subsequent motions which are not common to all bodies but are found only in lower bodies.

Among these motions, generation and corruption obtain the primacy. For alteration is directed to generation as to its end, and the end is by nature more perfect than what leads to it. Growth, likewise, is subsequent to generation, for growth does not take place without a certain particular generation, namely, that by which food is converted into the thing fed. Thus the Philosopher says in On the Soul II that food nourishes in so far as it is potentially flesh, but it produces increase inasmuch as potentially it is quantified flesh. Therefore, since these motions are in a certain way consequent upon generation, they must be studied along with generation and corruption.

2. Now it should be noted that whatever is found in a number of things should first be considered in common before coming to the specific cases. Otherwise the same thing will be frequently repeated, in that what is common will be repeated in each individual case, as the Philosopher proves in On the Parts of Animals I. Consequently, generation and corruption should be considered in common before coming to the parts [i.e., species] thereof. Likewise, it should be noted that if in any genus there be found some first thing which is the cause of the other things in that genus, the study of the common genus and of that which is first in that genus will belong to the same study. For that first thing is the cause of the entire genus, and anyone who studies some genus must consider the causes of the entire genus. That is why the Philosopher in the Metaphysics at once studies being in general and first being, which is separated from matter. Now in the genus of generable and corruptible things there are found certain first principles, namely, the elements, which are the cause of generation and corruption and alteration in all other bodies. Hence Aristotle in this book, which is the third part of natural science, discusses not only generation and corruption in general and other consequent motions, but also generation and corruption of the elements.

With these prefatory remarks to show Aristotle's intention in this book, we now arrive at its exposition.


12/21/2017 9:59 pm  #10

Re: Are generation and corruption "motions" in A-T?


I understand that you consider some of Aristotle's works earlier and less mature than others.  You assume that Aristotle changed his views over the course of his writings.  But from what I've read this is not a universal view.  There are others that consider each book to stand on it's own and is self-consistent within a particular book.  So the definitions Aristotle provides for a particular essay pertain to that essay even though it may seem at odds with other essays.

This quote from Aquinas shows that he considers "Generation and Corruption" the third installment of Aristotle's philosophy of natural science.  

Regardless of the chronology you assume of this writing, Aquinas considers it the third part and refers to changes of generation and corruption as motion.



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