SCG I, 42

Chapter 42: THAT GOD IS ONE [Quod Deus unus est]

… [2] For it is not possible that there be two highest goods, since that which is said by superabundance is found in only one being. But God, as we have shown, is the highest good. God is, therefore, one.

[3] Again, it has been shown that God is absolutely perfect, lacking no perfection. If, then, there are many gods, there must be many such perfect beings. But this is impossible. For, if none of these perfect beings lacks some perfection…, nothing will be given in which to distinguish the perfect beings from one another. It is impossible, therefore, that there be many gods.

[4] Again, that which is accomplished adequately through one supposition is better done through one than through many. But the order of things is the best it can be, since the power of the first cause does not fail the potency in things for perfection. Now, all things are sufficiently fulfilled by a reduction to one first principle. There is, therefore, no need to posit many principles.

Whiffs of "Ockham's razor" decades before Ockham.

[5] Moreover, it is impossible that there be one continuous and regular motion from many movers. For, if they move together, none of them is a perfect mover, but all together rather take the place of one perfect mover. This is not befitting in the first mover, for the perfect is prior to the imperfect. If, however, they do not move together, each of them at times moves and at times does not. It follows from this that motion is neither continuous nor regular. … But, as the philosophers have proved, the first motion is one and continuous. Therefore, its first mover must be one.

[6] Furthermore, a corporeal substance is ordered to a spiritual substance as to its good. For there is in the spiritual substance a fuller goodness to which the corporeal substance seeks to liken itself, since whatever exists desires the best so far as this is possible. … outside the spiritual substance that is the end of the first motion, there is none that is not reduced to it. But this is what we understand by the name of God. Hence, there is only one God.

[7] Among all the things that are ordered to one another, furthermore, their order to one another is for the sake of their order to something one; just as the order of the parts of an army among themselves is for the sake of the order of the whole army to its general. For that some diverse things should be united by some relationship cannot come about from their own natures as diverse things, since on this basis they would rather be distinguished from one another. Nor can this unity come from diverse ordering causes, because they could not possibly intend one order in so far as among themselves they are diverse. Thus, either the order of many to one another is accidental, or we must reduce it to some one first ordering cause that orders all other things to the end it intends. Now, we find that all the parts of this world are ordered to one another according as some things help some other things. … Nor is this something accidental, since it takes place always or for the most part. Therefore, this whole world has only one ordering cause and governor. But there is no other world beyond this one. Hence, there is only one governor for all things, whom we call God.

This is parallel to the fifth way in ST I.2.3, which is, incidentally, my favorite way:

"We see that things which lack intelligence, such as natural bodies, act for an end, and this is evident from their acting always, or nearly always, in the same way, so as to obtain the best result. Hence it is plain that not fortuitously, but designedly, do they achieve their end. Now whatever lacks intelligence cannot move towards an end, unless it be directed by some being endowed with knowledge and intelligence; as the arrow is shot to its mark by the archer. Therefore some intelligent being exists by whom all natural things are directed to their end; and this being we call God."

[8] Then, too, if there are two beings of which both are necessary beings, they must agree in the notion of the necessity of being. Hence, they must be distinguished by something added either to one of them only, or to both. This means that one or both of them must be composite. Now, as we have shown, no composite being is through itself a necessary being. It is impossible therefore that there be many beings of which each is a necessary being. Hence, neither can there be many gods.

[9] Furthermore, given two gods that are posited as agreeing in the necessity of being, either that in which they differ is in some way required for the completion of their necessity of being, or it is not. If it is not, then it is something accidental…. …unless that something else existed, this accident would not exist; and unless this accident existed, the aforesaid distinction would not exist. Therefore, unless that something else existed, these two supposed necessary beings would not be two but one. Therefore, the proper being of each depends on the other, and thus neither of them is through itself a necessary being.

[10] If, however, that in which they are distinguished is required to complete the necessity of their being, either this will be because it is included in the nature of this necessity of being, as animate is included in the definition of animal, or this will be because their necessity of being is specified by it, as animal is completed by rational. … A difference specifying a genus does not complete the nature of the genus, but rather through it the genus comes to be in act. For the nature of animal is complete before the addition of rational. Rather, the fact is that there cannot be an animal in act that is not rational or irrational. Thus, therefore, something completes the necessity of being as to being in act, and not as to the notion of the necessity of being. This is impossible on two counts. First, because the quiddity of a necessary being is its being, as was proved above. Second, because, were it true, the necessary being would acquire being through something else, which is impossible. …

[12] What is more, if there are two gods, either the name God is predicated of both univocally, or equivocally. … But if it be used univocally, it must be predicated of both according to one notion, which means that, in notion, there must be in both one nature. … If according to one, there will not be two gods, but only one, since there cannot be one being for two things that are substantially distinguished. If each has its own being, therefore in neither being will the quiddity be its being. Yet this must be posited in God….

[13] Again, nothing that belongs to this designated thing as such can belong to another, for the singularity of some thing belongs to none other than to that singular thing. But its necessity of being belongs to the necessary being so far as it is this designated being. Therefore, it cannot belong to another, and therefore there cannot be several beings of which each is a necessary being. …

[14] The proof of the minor. If the necessary being is not this designated being as a necessary being, the designation of its being is not necessary through itself but depends on another. But so far as each thing is in act it is distinct from all other things; this is to be this designated thing [hoc aliud res designata? So much for my stab at the Latin, which in fact is: quod est esse hoc signatum.]. Therefore, the necessary being depends on another to be in act; which is against the nature of the necessary being. Therefore, the necessary being must be necessary according as it is this designated being. …

[17] Then, too, the proper being of each thing is only one. But God is His being, as we have shown. There can, therefore, be only one God.

[18] Moreover, a thing has being in the manner it possesses unity. Hence, each thing struggles as much as it can against any division of itself, lest thereby it tend to nonbeing. But the divine nature has being most powerfully. There is therefore, in it the greatest unity, and hence no plurality is in any way distinguished within it.

Cf. SCG I.41.4

[19] Furthermore, we notice in each genus that multitude proceeds from some unity. This is why in every genus there is found a prime member that is the measure of all the things found in that genus. In whatever things, therefore, we find that there is an agreement in one respect, it is necessary that this depend upon one source. But all things agree in being. There must, therefore, be only one being that is the source of all things. This is God. …

Cf. SCG I.39.7. It is also parallel to the fourth way in ST I.2.3:

"Among beings there are some more and some less good, true, noble and the like. But "more" and "less" are predicated of different things, according as they resemble in their different ways something which is the maximum, as a thing is said to be hotter according as it more nearly resembles that which is hottest; so that there is something which is truest, something best, something noblest and, consequently, something which is uttermost being; for those things that are greatest in truth are greatest in being, as it is written in Metaph. ii. Now the maximum in any genus is the cause of all in that genus; as fire, which is the maximum heat, is the cause of all hot things. Therefore there must also be something which is to all beings the cause of their being, goodness, and every other perfection; and this we call God."

[22] Now by this truth are refuted those Gentiles who accepted a multitude of gods. However, many of them said that there was one highest God, by whom all the others whom they named gods were according to them caused. For they attributed the name of divinity to all everlasting substances, and this especially because of their wisdom and felicity and the rulership of things. …

[23] Hence, it is mainly the Manicheans who seem opposed to this truth, in that they posit two first principles of which one is not the cause of the other.

[24] The Arians likewise attacked this truth by their errors, in confessing that the Father and the Son are not one but several gods; although the authority of Scripture forces me to believe that the Son is true God.

SCG I, 39–41

Chapter 39: THAT THERE CANNOT BE EVIL IN GOD [Quod in Deo non potest esse malum]

[1] From this [viz. the substantial goodness of God, cf. SCG I, 38] it is quite evident that there cannot be evil in God.

[2] For being and goodness, and all names that are predicated essentially [omnia quae per essentiam dicuntur], have nothing extraneous mixed with them, although that which is or good can have something besides being and goodness. For nothing prevents the subject of one perfection from being the subject of another, just as that which is a body can be white and sweet. Now, each nature is enclosed within the limits of its notion [unaquaeque autem natura suae rationis termino concluditur], so that it cannot include anything extraneous within itself [nihil extraneum intra se capere possit]. But, as we have proved, God is goodness, and not simply good [Deus autem est bonitas, non solum bonus]. There cannot, therefore, be any non-goodness in Him [Non potest igitur in eo esse aliquid non bonitas]. Thus, there cannot possibly be evil in God.

[3] Moreover, what is opposed to the essence of a given thing cannot befit that thing so long as its essence remains. Thus, irrationality or insensibility cannot befit man unless he ceases to be a man [sicut homini non potest convenire irrationalitas vel insensibilitas nisi homo esse desistat]. But the divine essence is goodness itself, as we have shown. Therefore, evil, which is the opposite of good, could have no place in God—unless He ceased to be God, which is impossible [Ergo malum, quod est bono oppositum, in eo locum habere non potest nisi esse desisteret. Quod est impossibile], since He is eternal, as we have shown.

[4] Furthermore, since God is His own being, nothing can be said of Him by participation [nihil participative de ipso dici potest], as is evident from the above argument. If, then, evil is said of God, it will not be said by participation, but essentially. But evil cannot be so said of anything as to be its essence, for it would lose its being [malum de nullo dici potest ut sit essentia alicuius: ei enim esse deficeret], which is a good, as we have shown. In evil, however, there can be nothing extraneous mixed with it, as neither in goodness. Evil, therefore, cannot be said of God.

[5] Again, evil is the opposite of good. But the nature of the good consists in perfection, which means that the nature of evil consists in imperfection [i.e. inverted, regressive teleology]. Now, in God, Who is universally perfect, as we have shown above, there cannot be defect or imperfection. Therefore, evil cannot be in God.

[6] Then, too, a thing is perfect according as it is in act. A thing will therefore be imperfect according as it falls short of act [imperfectum erit secundum quod est deficiens ab actu]. Hence, evil is either a privation or includes privation. But the subject of privation is potency, which cannot be in God. Neither, therefore, can evil.

Annotated: "Denied by Buddhists, and by other Asiatic-minded and dissatisfied persons, who will have it that being is thought, or will, and that thought, will, and all conscious effort is misery."

[7] If, moreover, the good is “that which is sought by all,” it follows that every nature flees evil as such [malum unaquaeque natura refugit inquantum huiusmodi]. Now, what is in a thing contrary to the motion of its natural appetite is violent and unnatural. Evil in each thing, consequently, is violent and unnatural, so far as it is an evil for that thing; although, among composite things, evil may he natural to a thing according to something within it. But God is not composite, nor, as we have shown, can there be anything violent or unnatural in Him. Evil, therefore, cannot be in God.

[8] Scripture likewise confirms this. For it is said in the canonic Epistle of John (I, 1:5): “God is light and in Him there is no darkness”; and in Job (34:10) it is written: “Far from God be wickedness; and iniquity from the Almighty.”

Chapter 40: THAT GOD IS THE GOOD OF EVERY GOOD [Quod Deus est omnis omni bonum]

[1] From the foregoing it is also shown that God is “the good of every good.”’

[2] For the goodness of each thing is its perfection, as we have said. But, since God is absolutely perfect, in His perfection He comprehends the perfections of all things [sua perfectione omnes rerum perfectiones comprehendit], as has been shown [cf. SCG I, 31?]. His goodness, therefore, comprehends every goodness. Thus, He is the good of every good.

[3] Moreover, that which is said to be of a certain sort by participation is said to be such only so far as it has a certain likeness to that which is said to be such by essence. Thus iron is said to be on fire in so far as it participates in a certain likeness of fire [inquantum quandam similitudinem ignis participat]. But God is good through His essence, whereas all other things are good by participation, as has been shown. Nothing, then, will be called good except in so far as it has a certain likeness of the divine goodness. Hence, God is the good of every good.

[4] Since, furthermore, each thing is appetible because of the end, and since the nature of the good consists in its being appetible, each thing must be called good either because it is the end or because it is ordered to the end [boni autem ratio consistat in hoc quod est appetibile: oportet quod unumquodque dicatur bonum vel quia est finis, vel quia ordinatur ad finem]. It is the last end, then, from which all things receive the nature of good [Finis igitur ultimus est a quo omnia rationem boni accipiunt]. As will be proved later on, this is God. God is, therefore, the good of every good [Est igitur Deus omnis boni bonum].

[5] Hence it is that God, promising to Moses a vision of Himself, says: “I will show you all good” (Exod. 33:19). And in Wisdom (7:11), it is said of the divine wisdom: “All good things come to me together with her.”

Chapter 41: THAT GOD IS THE HIGHEST GOOD [Quod Deus sit summum bonum]

[1] From this conclusion we prove that God is the highest good.

[2] For the universal good stands higher than any particular good, just as “the good of the people is better than the good of an individual,” since the goodness and perfection of the whole stand higher than the goodness and perfection of the part. But the divine goodness is compared to all others as the universal good to a particular good, being, as we have shown, the good of every good [omnis boni bonum]. God is, therefore, the highest good.

[3] Furthermore, what is said essentially is said more truly than what is said by participation. But God is good essentially, while other things are good by participation, as we have shown. God is, therefore, the highest good.

[4] Again, “what is greatest in any genus is the cause of the rest in that genus,” [Quod est maximum in unoquoque genere est causa aliorum quae sunt in illo genere] for a cause ranks higher than an effect [causa enim potior est effectu]. But, as we have shown, it is from God that all things have the nature of good. God is, therefore, the highest good.

This is a key passage for understanding the fourth way in the Summa theologica I, 2, 3, which in turn must be read in conjunction with SCG I, 38: each thing's good is the motor for its act of being, its formal perfection, and, as God is the highest good and cause of all beings' be-ing, so He is the perfection of every formal category of being, though He is not properly contained within any genus (cf. SCG I, 25–27).

[5] Moreover, just as what is not mixed with black is more white, so what is not mixed with evil is more good. But God is most unmixed with evil, because evil can be in God neither in act nor in potency; and this belongs to God according to His nature, as we have shown. God is, therefore, the highest good.

[6] Hence what is written in 1 Samuel (2:2): “There is none holy as the Lord is.”