See the first post in this series for an explanation and guide of our tour of Summa Contra Gentiles.
This is the last of the necessary but, it must be admitted, less-than-riveting introductory posts. It must be kept in mind that Summa Contra Gentiles is primarily a Teacher’s Guide and not per se a text for students. We’re adapting it as we go. Next week we launch into the good stuff, the first proofs for the existence of God. We’ve sped up to get here, but next week we reduce pace dramatically since to progress we need material Aquinas assumes but which we Moderns have largely forgotten.
Chapter 8: In what relation human reason stands to the truth of faith
(1) IT would also seem well to observe that sensible things from which human reason derives the source of its knowledge, retain a certain trace of likeness to God, but so imperfect that it proves altogether inadequate to manifest the substance itself of God. For effects resemble their causes according to their own mode, since like action proceeds from like agent; and yet the effect does not always reach to a perfect likeness to the agent…i
Chapter 9: Of the order and mode of procedure in this work
…(2) Wherefore in order to deduce the first kind of truth we must proceed by demonstrative arguments whereby we can convince our adversaries. But since such arguments are not available in support of the second kind of truth, our intention must be not to convince our opponent by our arguments, but to solve the arguments which he brings against the truth, because, as shown above, natural reason cannot be opposed to the truth of faith.ii
In a special way may the opponent of this kind of truth be convinced by the authority of Scripture confirmed by God with miracles: since we believe not what is above human reason save because God has revealed it. In support, however, of this kind of truth, certain probable arguments must be adduced for the practice and help of the faithful, but not for the conviction of our opponents, because the very insufficiency of these arguments would rather confirm them in their error, if they thought that we assented to the truth of faith on account of such weak reasonings.iii
(3) …we shall first of all endeavour to declare that truth which is the object of faith’s confession and of reason’s researches, by adducing arguments both demonstrative and probable, some of which we have gathered from the writings of the philosophers and of holy men, so as thereby to confirm the truth and convince our opponents…
(4) Seeing then that we intend by the way of reason to pursue those things about God which human reason is able to investigate, the first object that offers itself to our consideration consists in those things which pertain to God in Himself…Of those things which we need to consider about God in Himself, we must give the first place (this being the necessary foundation of the whole of this work), to the question of demonstrating that there is a God: for unless this be established, all questions about divine things are out of court.iv
Chapter 10: Of the opinion of those who aver that it cannot be demonstrated that there is a God, since this is self-evident
(1) POSSIBLY it will seem to some that it is useless to endeavour to show that there is a God: they say that it is self-evident that God is, so that it is impossible to think the contrary, and thus it cannot be demonstrated that there is a Godv…
(2) Those things are said to be self-evident which are known as soon as the terms are known: thus as soon as it is known what is a whole, and what is a part, it is known that the whole is greater than its part…
Chapter 11: Refutation of the foregoing opinion and solution of the aforesaid arguments
(5)…For just as it is self-evident to us that a whole is greater than its part, so is it most evident to those who see the very essence of God that God exists, since His essence is His existence. But because we are unable to see His essence, we come to know His existence not in Himself but in His effectsvi…
Chapter 12: Of the opinion of those who say that the existence of God cannot be proved, and that it is held by faith alone
(1) THE position that we have taken is also assailed by the opinion of certain others, whereby the efforts of those who endeavour to prove that there is a God would again be rendered futile. For they say that it is impossible by means of the reason to discover that God exists, and that this knowledge is acquired solely by means of faith and revelationvii…
(5) [Another potential counterargument.] If the principles of demonstration become known to us originally through the senses, as is proved in the Posterior Analytics, those things which transcend all sense and sensible objects are seemingly indemonstrable. Now such is the existence of God. Therefore [opponents say] it cannot be demonstrated…
(9) It is also evident from the fact that, although God transcends all sensibles and senses, His effects from which we take the proof that God exists, are sensible objects. Hence our knowledge, even of things which transcend the senses, originates from the senses.viii
iWe made this point before, but you watching a man crush an aluminum can would not allow you to infer his complete strength, neither would following him solve “2 + 7” allow you to plumb his intellectual depths. Neither can we look out into the world and learn all about God. However, that you see a man crush a man indicates that there is a man crushing the can, and that you see a man solve an equation proves there is an existing intellect.
iiAs promised, nothing but logical proof for our fundamental claims. No revelations drawn upon. All unbelievers can play. But if somebody makes a claim against Scripture, Aquinas is ready to defend.
iiiWe wouldn’t want our adversaries thinking we believe in flying spaghetti monsters simply because we wanted to believe. Indeed, the pasta sauce will soon be on the other foot. Opponents are going to have to work very hard indeed to counter the arguments which are coming. Be warned that they stood for roughly two-and-a-half millennia. Your task won’t be easy; in fact, it will be impossible.
ivWe are all in agreement here, I hope and pray.
vWhat follows here and in Chapter 11 is St Anselm’s so-called ontological argument and a refutation of the same and two other similar arguments. That God is self-evident and not in need of proof is not a problem for moderns in the least. Consequently, as interesting as Thomas’s arguments are on this matter, we pass on quickly.
viWe cannot know God as He is in himself. Most of us can barely remember what we had for lunch last Tuesday, let alone grasp the Infinite. Aquinas is not trying to slip in an Intelligent Design (as moderns know the term) argument. And he was most certainly not a Creationist in any sense beyond believing that God was—and is, even at this moment—the cause of the universe (for the universe had to and must currently have a cause, as we’ll see).
viiThis has become a slur in our time. Only fools believe by faith. The intelligent know by science. Of course, this sad formula ignores that many things must be taken on faith or reason goes nowhere. We have discussed axioms as a primary instance. But never mind all that. This is our last warning, one I predict which will be forgotten in the weeks to come, that our proofs are fundamental and require the exact same amount of faith that any mathematician or physicist brings to his tasks.
viiiJust as in mathematics we know of infinity, and its various flavors and sizes, but cannot savor these flavors nor comprehend these sizes, so can we prove (and will) certain things about God’s nature. For instance, we can say He is Omnipotent, and even define the broad outlines of this quality, but moving from that to knowing just what’s on God’s mind? You can’t get there from here, not using unaided the weak powers of the human mind.
But enough! We are at this point in the position of children rankling under the forced repetition of scales, anxious to move to our first melody. It is a sweet tune, our starting one. Aristotle started humming it a long time ago and it hasn’t lost any of its vigor or shine by repetition. To continue this silly metaphor, it’s a song that once you hear it you can’t get out of your head. Nor will you want to.
 Ch. vii.
 2 Poster. ix. i., xviii. [Aristotle]