Skip to content

Category: SAMT

A tour through Saint Thomas Aquinas’s Summa Contra Gentiles.

October 5, 2014 | 21 Comments

Summary Against Modern Thought: Periodic Review

This may be proved in three ways. The first...
This may be proved in three ways. The first…
See the first post in this series for an explanation and guide of our tour of Summa Contra Gentiles. All posts are under the category SAMT.

Let’s catch up so that we’re not in danger of forgetting where we came from, where we are, and where we’re going. I do not mean here to give complete arguments. That has already been done in the original posts. What follows is only a sketch to reorient and reinvigorate us. Don’t be lazy.

Does God exist? How do we know? Given the logical implications of answering those questions, how do we explain what can we know about God? What can we know about God? Well, some things, but not every thing. But more than you’d guess. These questions, all worthy and deserving of our attention, form the discourse of Book One of SCG. Let’s review.

Our efforts will not be in vain. From Chapter 3: “Now in those things which we hold about God there is truth in two ways. For certain things that are true about God wholly surpass the capability of human reason, for instance that God is three and one: while there are certain things to which even natural reason can attain, for instance that God is, that God is one, and others like these, which even the philosophers proved demonstratively of God, being guided by the light of natural reason.”

Let’s don’t be lazy; let’s attack each point assiduously, as argued in Chapter 4. Why? Because “the checking of presumption which is the mother of error” Chapter 5. Repeat that thrice. Most of what we believe is given to us. Let’s think things through, guided by those of superior intelligence. God is an embarrassing subject for our world, except to denigrate religion or sneer at theology, these unthinking irrational ill-educated attitudes being thought a mark of sophistication. Don’t be lazy.

The proof, using only reason and not a whit of divine revelation (beyond that which we all possess) which forms the backbone of Aquinas’s efforts, is that of first motion, which begins in Chapter 13 (part 2, part 3, part 4, part 5; don’t be lazy).

3 The first way is as follows. Whatever is in motion is moved by another: and it is clear to the sense that something, the sun for instance, is in motion. Therefore it is set in motion by something else moving it. Now that which moves it is itself either moved or not. If it be not moved, then the point is proved that we must needs postulate an immovable mover: and this we call God. If, however, it be moved, it is moved by another mover. Either, therefore, we must proceed to infinity, or we must come to an immovable mover. But it is not possible to proceed to infinity. Therefore it is necessary to postulate an immovable mover.

This simple and quite beautiful eminently reasonable and (thus far?) irrefutable argument has never stopped being misunderstood. Aquinas, and we following him, went to great pains to show that this movement is here-and-now. That which accounts for how any movement, which is to say how any change, happens must be because of a First Mover, an Unchanging Changer.

From this argument we learned (among other things) the concepts of act and potential. Something actual changes a thing from one “state” to another “state”, which before the change was only a potential. It cannot be the potential that is an efficient cause, it must be something actual.

What follows from this is that, because for any and all change there must be a First Changer, that God is not only “everywhere”—but not in the pagan sense; in the sense that if God did not exist, the universe would immediately cease—but God is also eternal, outside time, because time is the measure of movement, and God is Unmoving, Chapter 15. Few of these terms carry the same colloquial definitions we ordinarily carry, so don’t be lazy: read the original argument.

Another consequence is that God does not have any passive potentiality, Chapter 16.

2 For everything in whose substance there is an admixture of potentiality, is possibly non-existent as regards whatever it has of potentiality, for that which may possibly be may possibly not be. Now God in Himself cannot not be, since He is eternal. Therefore in God there is no potentiality to be

Not surprisingly, from these we learn that God is not made of matter. He is not physical stuff, Chapter 17. God is not the god of the atheists; He is not a clever, long-lived alien being composed (say) of energy fields. God is beyond matter: He is spirit.

It immediately follows that God is not made of parts, that he is “simple”, Chapter 18.

1 For in every composite thing there must needs be act and potentiality: since several things cannot become one simply, unless there be something actual there and something else potential. Because those things that are actually, are not united except as an assemblage or group, which are not one simply. In these moreover the very parts that are gathered together are as a potentiality in relation to the union: for they are actually united after being potentially unitable. But in God there is no potentiality. Therefore in Him there is no composition.

Another consequence: there is nothing in God against Nature, Chapter 19, and that God is not a body, Chapter 20, the simplest demonstration of which is, “For since every body is a continuous substance, it is composite and has parts. Now God is not composite, as we have shown. Therefore He is not a body.”

This brings us up to date. God exists, is responsible for the universe remaining in existence and is the ultimate cause of all change, that He is eternal, that He has no potential, that He is not made of stuff and is not a body. Well, fine. But that doesn’t tell us much. This could all describe the some kind of weird immaterial physical uber-field. Though we’ve gone a great distance, we haven’t really done much. We haven’t come close to describing God in full.

But we still have 80 chapters to go! Don’t be lazy.

September 28, 2014 | 3 Comments

Summary Against Modern Thought: God Is Not A Body. Part III

This may be proved in three ways. The first...
This may be proved in three ways. The first…
See the first post in this series for an explanation and guide of our tour of Summa Contra Gentiles. All posts are under the category SAMT.

Previous post.

This is the last part proving God is not a body (more proofs, that is; we have already had several), a proposition which in unfamiliar to moderns and therefore not under much dispute, except for the steady stream of demiurges put forth by modern atheists as misconceptions of who or what God is. Yet I see that we’re growing weary of this subtopic, and so we’ll finish it today, and in a circumscribed fashion. I’ll also keep my footnotes to a minimum. Don’t forget we already know the Unmoved Mover, God, is outside time, i.e. is eternal. There are a lot of infinities involving God, and today we meet some of them. Next week, we start on a new and essential topic, that God is His own essence.

Chapter 20: That God is not a body

13That the power of the first mover is infinite is proved thus. No finite power can cause movement in an infinite time. Now the power of the first mover causes movement in an infinite time, since the first movement is eternal. Therefore the power of the first mover is infinite.i

The first proposition is proved thus. If any finite power of a body causes movement in infinite time, a part of that body having a part of that power, will cause movement during less time, since the greater power a thing has, for so much the longer time will it be able to continue a movement, and thus the aforesaid part will cause movement in finite time, and a greater part will be able to cause movement during more time. And thus always according as we increase the power of the mover, we increase the time in the same proportion. But if this increase be made a certain number of times we shall come to the quantity of the whole or even go beyond it. Therefore the increase also on the part of the time will reach the quantity of time wherein the whole causes movement. And yet the time wherein the whole causes movement was supposed to be infinite. Consequently a finite time will measure an infinite time: which is impossible…ii

16The second objection is that, although a body be divided, it is possible for a power of a body not to be divided when the body is divided, thus the rational soul is not divided when the body is divided.iii

17To this we reply that by the above argument it is not proved that God is not united to the body as the rational soul is united to the human body, but that He is not a power residing in a body, as a material power which is divided when the body is divided. Wherefore it is also said of the human intellect that it is neither a body nor a power in a body.[11] That God is not united to the body as its soul, is another question.[12]

18The third objection is that if the power of every body is finite, as is proved in the above process; and if a finite power cannot make its effect to endure an infinite time; it will follow that no body can endure an infinite time: and consequently that a heavenly body will be necessarily corrupted. Some reply to this that a heavenly body in respect of its own power is defectible, but acquires everlastingness from another that has infinite power. Apparently Plato approves of this solution, for he represents God as speaking of the heavenly bodies as follows: By your nature ye are corruptible, but by My will incorruptible, because My will is greater than your necessity.[13]iv

19But the Commentator refutes this solution in 11 Metaph. For it is impossible, according to him, that what in itself may possibly not be, should acquire everlastingness of being from another: since it would follow that the corruptible is changed into incorruptibility; and this, in his opinion, is impossible. Wherefore he replies after this fashion: that in a heavenly body whatever power there is, is finite, and yet it does not follow that it has all power; for, according to Aristotle (8 Metaph.)[14] the potentiality to (be) somewhere is in a heavenly body, but not the potentiality to be. And thus it does not follow that it has a potentiality to not-be.

It must be observed, however, that this reply of the Commentator is insufficient.v Because, although it be granted that in a heavenly body there is no quasi-potentiality to be, which potentiality is that of matter, there is nevertheless in it a quasi-active potentiality, which is the power of being: since Aristotle says explicitly in 1 Coeli et Mundi,[15] that the heaven has the power to be always. Hence it is better to reply that since power implies relation to act, we should judge of power according to the mode of the act. Now movement by its very nature has quantity and extension, wherefore its infinite duration requires that the moving power should be infinite. On the other hand being has no quantitative extension, especially in a thing whose being is invariable, such as the heaven. Hence it does not follow that the power of being a finite body is infinite though its duration be infinite: because it matters not whether that power make a thing to last for an instant or for an infinite time, since that invariable being is not affected by time except accidentally…

28Again. No movement that tends towards an end which passes from potentiality to actuality, can be perpetual: since, when it arrives at actuality, the movement ceases. If therefore the first movement is perpetual, it must be towards an end which is always and in every way actual. Now such is neither a body nor a power residing in a body; because these are all movable either per se or accidentally. Therefore the end of the first movement is not a body nor a power residing in a body. Now the end of the first movement is the first mover, which moves as the object of desire:[21] and that is God. Therefore God is neither a body nor a power residing in a body…vi

31Hereby is refuted the error of the early natural philosophers,[23] who admitted none but material causes, such as fire, water and the like, and consequently asserted that the first principles of things were bodies, and called them gods. Among these also there were some who held that the causes of movement were sympathy and antipathy: and these again are refuted by the above arguments. For since according to them sympathy and antipathy are in bodies, it would follow that the first principles of movement are forces residing in a body. They also asserted that God was composed of the four elements and sympathy: from which we gather that they held God to be a heavenly body. Among the ancients Anaxagoras alone came near to the truth, since he affirmed that all things are moved by an intellect.

32By this truth, moreover, those heathens are refuted who maintained that the very elements of the world, and the forces residing in them, are gods; for instance the sun, moon, earth, water and so forth, being led astray by the errors of the philosophers mentioned above.vii


i[Comment updated to fix stupid typo.] Don’t forget to review what these terms mean. The first movement is not some movement that caused the universe to start on its way in the dim dark past. It is the movement that starts all other movements, and we have seen that it must take no time. Again, I ask you to review Chapter 13. And Chapter 17, which proves God is not made of matter, and Chapter 15, which proves God is eternal. These are all premises here.

iiThis is not as bad as it looks when you first scan it. Read it. Two objections answered about conditionals and divided bodies are skipped.

iiiThe first time we hear the soul is immaterial! See also the next point, at that word “united.” This is only a hint of what is to come in other books of STG. Book One is all God all the time. Do not become a Descartesian over this one small word.

iv“For the sword outwears its sheath…And the soul wears out the breast.”

vSo much for slavishly following his predecessor!

viThis is pretty, but you must have Chapter 13 assimilated before you understand what he’s talking about. For instance, movement is actualization of a potential, and some actual power must actualize the potential. Potentials are powerless. (There’s a new business slogan for you.)

viiThe two-paragraph passage has interest in itself, as philosophical history, but is also proof that progress can be and is had in philosophy and theology, just like in science. Decay and distraction, again just in like science, also happen. Theology is thus, in the same sense as science, self correcting.

[11] Cf. Bk. II., ch. lvi.
[12] Cf. Ch. xxvii.
[13] Timaeus xli.
[14] D. 7, iv. 6.
[15] Ch. iii. 4; xii. 3.
[16] See above: But the Commentator…p. 46.
[17] 3, iv. 11; 6, ii. 8.
[18] Averroës, 12 Metaph. t. c. 41.
[19] See above: To this we reply…p. 46.
[20] Ch. vii. seqq.
[21] Cf. ch. xiii.: Since, however,…p. 31.
[22] Bk. IV., ch. xcvii.
[23] Cf. 1 Phys. ii.

September 14, 2014 | 2 Comments

Summary Against Modern Thought: God Is Not A Body. Part II

This may be proved in three ways. The first...
This may be proved in three ways. The first…
See the first post in this series for an explanation and guide of our tour of Summa Contra Gentiles. All posts are under the category SAMT.

Previous post.

God is not a physical body, that God is not a creature continued…but not finished today. We have instead a series of nested arguments, so it will take some careful reading to keep up. Each argument contains a premise, which is proved in the next point, which itself (once or twice) has a premise proved by the next point after. This goes on at some length; indeed, we will not finish the proof this week. Plus we ranging into analysis-like subjects, which aren’t always easy to keep in mind.

Chapter 20: That God is not a body

9 Again. No infinite power is a power residing in a magnitude. But the power of the first mover is an infinite power. Therefore it does not reside in a magnitude. And thus God, Who is the first mover, is neither a body nor a power residing in a body.i

10 The first proposition is proved as follows. If a power residing in a magnitude be infinite, this magnitude is either finite or infinite. But there is no infinite magnitude, as proved in 3 Phys.[8] and 1 Coeli et Mundi.[9] And it is not possible for a finite magnitude to have an infinite power. Therefore in no magnitude can there be an infinite power.ii

11 That there cannot be an infinite power in a finite magnitude is proved thus. A great power produces in less time an equal effect, which a lesser power produces in more time: of whatever kind this effect may be, whether it be one of alteration, of local movement, or of any other kind of movement. Now an infinite power surpasses every finite power. It follows therefore that it produces its effect more rapidly, by causing a more rapid movement than any finite power. Nor can this greater rapidity be one of time. Therefore it follows that the effect is produced in an indivisible point of time. And thus moving, being moved, and movement will be instantaneous: the contrary of which has been proved in 6 Phys.[10]iii

12 That an infinite power of a finite magnitude cannot cause movement in time, is proved thus. Let A be an infinite power; and AB a part thereof. This part therefore will cause movement in more time. And yet there must be proportion between this time and the time in which the whole power causes movement, since both times are finite. Suppose then these two times to be in proportion as 1 to 10, for it does not affect this argument whether we take this or any other ratio.

Now if we increase the aforesaid finite power, we must decrease the time in proportion to the increase of the power, since a greater power causes movement in less time. If therefore we increase it tenfold, that power will cause movement in a time which will be one-tenth of the time occupied by the first part that we took of the infinite power, namely AB. And yet this power which is ten times the aforesaid power is a finite power, since it has a fixed proportion to a finite power. It follows therefore that a finite power and an infinite power cause movement in an equal time: which is impossible. Therefore an infinite power of a finite magnitude cannot cause movement in any time.iv


iThis highlights something I think sadly neglected by physicists. That to create something out of nothing, or to be the First Mover (in the Chapter 13 sense; also see this), requires infinite “power.” Just what power and how does that relate to other things we know or conjecture about the universe is very little is known. Infinity is a strange place, as we emphasize repeatedly and to say our intuitions aren’t in it is the minimum. Mathematics barely touches on it. Spheres that can fold themselves inside out without breaking? Can be split in two and be the same in size? Weird!

iiWe’re into the Land of Subtly here, where it is easy to get lost. Don’t forget our destination. That the Infinite cannot be a body. Now if God were an infinite body, that is all there would be. There would be no room for us. God would take up all the space. So God has to be something other than a body, while still being infinite. But what? That’s what the rest of this book of Summa Contra Gentiles is about: describing that what.

It seems to me that we are not at a sticking point, that the reader is willing to grant that God is not an infinite physical body. So I don’t want to take up space with minutiae; nevertheless, if you’re interested in the details, read Chapter 5 of Aristotle here.

iiiNon-locality anyone? How can entangled particles the distance of the universe apart instantaneously “decide” which states to take? Do we have an answer here, in the First Mover, or are things buried more deeply?

ivWe have a proof by contradiction. Perhaps it’s easy to miss, but St Thomas is assuming first that the infinite power causes an effect in finite time. The idea is that, by simple manipulation, if the infinite power causes an effect in any time whatsoever, we can construct a finite power that causes the effect in the same amount of time. This cannot be, thus the infinite power must operate instantaneously.

The proofs of the remaining premises aren’t in this article. We attack these next week because, I think, we’ve already reached the limit today (get it? get it? theological cum mathematical humor; plus, Yours Truly is rather in a hurry today).

[8] Ch. v.
[9] Ch. v. seqq.
[10] Ch. iii.

September 7, 2014 | 3 Comments

Summary Against Modern Thought: God Is Not A Body. Update

This may be proved in three ways. The first...
This may be proved in three ways. The first…
See the first post in this series for an explanation and guide of our tour of Summa Contra Gentiles. All posts are under the category SAMT.

Previous post.

Update I haven’t any idea how I did it, but I somehow turned off comments on this post. They are now restored.

The conception of what God is went downhill after Aquinas. And, dear atheist reader, shouldn’t you know what it is you claim to reject? New Atheists in particular have been shockingly Would it surprise you to learn that the Church rejects the same gods, or same weakened conception of God, you reject? This chapter, which is broken over multiple posts, shows that God is not a physical body, that God is not a creature.

Chapter 20: That God is not a body

1 FROM the foregoing we are also able to prove that God is not a body.

2 For since every body is a continuous substance, it is composite and has parts. Now God is not composite, as we have shown.[1] Therefore He is not a body.

3 Further. Every quantitative substance is somehow in potentiality: for that which is continuous is potentially divisible to infinity; and number can be infinitely augmented.i Now every body is a quantitative substance. Therefore every body is in potentiality. But God is not in potentiality, but is pure act, as shown above.[2]ii Therefore God is not a body.

4 Again. If God were a body, He would needs be a physical body, for a mathematical body does not exist by itself, as the Philosopher proves,[3] since dimensions are accidents.iii Now He is not a physical body; for He is immovable, as we have proved,[4] and every physical body is movable. Therefore God is not a body.

5 Moreover. Every body is finite, which is proved in regard both to spherical and to rectilinear bodies in 1 Coeli et Mundi.[5] Now we are able by our intellect and imagination to soar above any finite body. Wherefore, if God were a body, our intellect and imagination would be able to think of something greater than God: and thus God would not exceed our intellect: which is inadmissible. Therefore He is not a body.iv

6 Furthermore. Intellective knowledge is more certain than sensitive. Now among natural things we find some that are objects of sense: therefore there are also some that are objects of intellect. But the order of powers is according to the order of objects, in the same way as their distinction. Therefore above all sensible objects there is an intelligible object existing in natural things. But every body that exists among things is sensible. Therefore above all bodies it is possible to find something more excellent. Wherefore if God were a body, He would not be the first and supreme being.v

7 Again. A living thing is more excellent than any body devoid of life. Now the life of a living body is more excellent than that body, since thereby it excels all other bodies. Therefore that which is excelled by nothing, is not a body. But such is God. Therefore He is not a

8 Moreover. We find the philosophers proving the same conclusion by arguments[6] based on the eternity of movement, as follows. In all everlasting movement the first mover must needs not be moved, neither per se nor accidentally, as we have proved above.[7] Now the body of the heavens is moved in a circle with an everlasting movement. Therefore its first mover is not moved, neither per se nor accidentally. Now no body causes local movement unless itself be moved, because moved and mover must be simultaneous; and thus the body that causes movement must be itself moved, in order to be simultaneous with the body that is moved. Moreover no power in a body causes movement except it be moved accidentally; since, when the body is moved, the power of that body is moved accidentally. Therefore the first mover of the heavens is neither a body nor a power residing in a body. Now that to which the movement of the heavens is ultimately reduced as to the first immovable mover, is God. Therefore God is not a body.vii


iWho knew St Thomas was familiar with analysis! (The first argument above I left uncommented, it being obviously sound.)

iiDon’t forget to review what these terms mean, particularly act and potential. Don’t assume you know how St Thomas and Aristotle meant them.

iiiFrom The Philosopher, lovely as always (yes, but was this peer-reviewed?):

A question connected with these is whether numbers and bodies and planes and points are substances of a kind, or not. If they are not, it baffles us to say what being is and what the substances of things are. For modifications and movements and relations and dispositions and ratios do not seem to indicate the substance of anything; for all are predicated of a subject, and none is a ‘this’…

But if this is admitted, that lines and points are substance more than bodies, but we do not see to what sort of bodies these could belong (for they cannot be in perceptible bodies), there can be no substance. Further, these are all evidently divisions of body, one in breadth, another in depth, another in length…

iv(Heaven and Earth.) St Anselm, anyone? Don’t let’s forget that Contra Gentiles came before Summa Theologica in Aquina’s thinking. See 2c here.

vAs a sound argument, this bullet is shaky, assuming what it seeks to prove, it seems to me, at the end, in much the same way as the ontological argument fails. But, the first premise is certainly true: “Intellective knowledge is more certain than sensitive.” One can mistake cold for hot, but not that you know. This is why many also say mathematical knowledge is supreme.

viThis one is too telegraphic, maybe. We have “Therefore that which is excelled by nothing, is not a body”, which we can grant. But angels are not bodies, and we haven’t yet shown that these are lesser than God. Certainly, this argument is weak. But. If, as he does, St Thomas offers two dozen arguments for a proposition, and one or two fail, this does not imply the others fail, which (as shown) they do not. Do not be intellectually lazy and ponder only that which is admitted to fail. And anyway, like the ontological argument, much can be learned from the failures of these arguments.

viiIf you key in on the heavens moving circularly bit, you’ll be missing the point. This argument, which does not for a mote rely on that contention, is really no different than the proof of God’s existence because in order for anything to move—here and now—we need a first unmoved mover. Go back and read Chapter 13, as St Thomas himself commands in the footnotes.

[1] Ch. xviii.
[2] Ch. xvi.
[3] 2 Metaph. v. [This is a typo; it should be 3 Metaph. v.]
[4] Ch. xiii.
[5] Ch. v. seqq.
[6] 7 and 8 Phys. See above, ch. xiii.
[7] Ch. xiii.

[6] 7 and 8 Phys. See above, ch. xiii.