Article 3 — Whether God is contained in a genus

The third point of inquiry is whether God is contained in a genus. (Parallel texts: ST I.3.5; SCG I.25; In I Sent. 8.4.2; 19.4.2; Compendium theologiae, ch. 12; On Being and Essence, ch. 4.)

Obj. 1: And it seems that he is. For Damascene says: “substance” in God denotes the common species of the three persons like in species; “hypostasis” indicates the individual, for instance, the Father, the Son, and Holy Spirit, Peter or Paul. (John Damascene, On the Orthodox Faith 3.4 (PG 94:997–98).) Thus, God is compared to the Father, Son, and Holy Spirit as a species to individuals. Now, wherever there is a species with individuals, there is a genus, since the species is composed of its genus and a difference. Therefore, it seems that God is contained in a genus.

Obj. 2: Things which are in no way different are identical. But God is not identical with other things; therefore, in some way he is different from them. Now, that which is different from something else differs therefrom by some difference. Therefore, there is a difference in God, by which he differs from other things. But it is not an accidental difference, since nothing in God is accidental, as Boethius says in On the Trinity. (Boethius, On the Trinity 5 (PL 64:1254).) And every substantial difference makes a division of a genus. Therefore, God is contained in a genus.

Obj. 3: Things may be the same either in genus, or in species, or in number, as is said in Topics 1. (Aristotle, Topics 1.7, 103a6–15.) Therefore, things may also differ in these ways, since if one of two opposites admits of multiplicity, the other does so too. Therefore, God is distinct from a creature, either in number only, or in number and species, in which case he will be in the same genus as the creature and consequently will be contained in a genus. However, if he will differ from the creature in genus, he will be in a different genus than the creature; for diversity results from multitude, and thus that difference of genus implies a multitude of genera. Therefore, in any case God must be contained in a genus.

Obj. 4: Anything to which the account of the genus substance applies is in a genus. Now, the account of substance is self-subsistence, which is most applicable to God. Therefore, God is in the genus of substance.

Obj. 5: Anything that can be defined must be in a genus. Now, God can be defined, for he is said to be pure act. Therefore, God is contained in a genus.

Obj. 6: Whatsoever is predicated of another as what it is, and is predicated of other things besides, is compared to that thing either as its species or as its genus. Now, all things predicated of God are predicated of him as what he is, since all the categories when applied to God refer to his substance, as Boethius says. (Boethius, On the Trinity 4–5 (PL 64:1253–54).) And it is clear that they are applicable not only to God but to other things besides. Therefore, they are compared to God either as a species to an individual or as a genus to its species, and in either case God must be contained in a genus.

Obj. 7: A thing is measured by what is least in its own genus, as is said in Metaphysics 10. (Aristotle, Metaphysics 10.1, 1052b19–22; 10.2, 1053b16–105412.) Now, according to the Commentator, God is the measure of all substances. (Averroes, Commentary on the Metaphysics 10.) Therefore, God is in the same genus as other substances.

On the contrary (1), whatsoever is contained in a genus contains something in addition to the genus, and therefore it is composite. But God is utterly simple. Therefore, he is not contained in a genus.

Furthermore (2), whatsoever is contained in a genus can be defined or else comprised under something that is defined. But this cannot apply to God, since he is infinite. Therefore, he is not in a genus.

I answer that God is not contained in a genus, and for the present this may be proved by three arguments.

The first argument is that nothing is assigned to a genus by reason of its own being but by reason of its quiddity; this is clear from the fact that the being of a thing is proper to that thing and distinct from the being of anything else, while the account of its substance can be common. This is also why the Philosopher says that being is not a genus. (Aristotle, Metaphysics 3.3, 998b11–999a23.) Now, God is his own being itself; therefore, he cannot be in a genus.

The second argument is that, although matter is not a genus nor form a difference, nevertheless the account of the genus is taken from the matter, and the account of the difference from the form. For instance, in man the sensible nature, from which the account of animality is taken, is material in relation to reason, from which is taken the difference of rationality. For an animal is that which has a sensitive nature, and a rational being is one that has reason. Hence, in everything that is contained in a genus there must be composition of matter and form or of act and potency, and this cannot be in God who is pure act, as we have shown. (Q. 7, a. 1.) Therefore, he cannot be in a genus.

The third argument is that, since God is simply perfect, he contains the perfections of all genera, for this is what is meant by being simply perfect, as is said in Metaphysics 5. (Aristotle, Metaphysics 5.16, 1021b30–1022a1; cf. 10.4, 1055a10.) Now, that which is contained in a genus is confined within the limits of that genus. Therefore, God cannot be in a genus, for in that case his essence would not be infinite nor absolutely perfect, but his essence and perfection would be confined within the account of a definite genus.

Hence, it is also evident that God is neither a species nor an individual, nor is there difference in him. Nor can he be defined, since every definition is taken from the genus and species. Therefore, neither can we demonstrate anything about him, save from his effects, since the middle term of a demonstration through the cause is a definition.

Reply Obj. 1: Damascene uses the word “species” metaphorically and not in the strict sense. (John Damascene, On the Orthodox Faith 3.4 (PG 94:997–98).) The name “God” is like a species in that it is predicated essentially of several distinct individuals, but it cannot be called a species strictly speaking, since a species is not something numerically one that is common to the many; rather it is one only in account, while the numerically one divine essence is common to the three persons; therefore, Father, Son, and Holy Spirit are one God, but Peter, Paul, and Mark are not one man.

Reply Obj. 2: A distinction is to be noted between difference and diversity, according to the Philosopher. (Aristotle, Metaphysics 10.3, 1054b23–31.) For what is not the same is called “diverse” absolutely, whereas “different” is said in reference to something, since everything different differs in some respect. Accordingly, if we take the term “different” properly, it is not true that things that are and are in no way different are the same; but if we take the term “different” in a broad sense, it is true, and in this sense we grant that God differs from other things. It does not follow, however, that he differs by some difference but that he differs from other things through his own essence; for this must be the case in first and simple things. Thus, man differs from a donkey by the difference of rationality, but rationality is not distinguished from a donkey by a still further difference (since thus this would go on to infinity); rather, it differs therefrom by itself.

Reply Obj. 3: God is said to be diverse in genus from creatures not as though he were contained in another genus, but because he is altogether outside a genus.

Reply Obj. 4: According to Avicenna, substance is not rightly defined as a self-subsistent being, (Avicenna, The Metaphysics of the Healing 3.8.) for being cannot be the genus of a thing, as the Philosopher proves; (Aristotle, Metaphysics 3.3, 998b11–999a23.) because nothing can be added to being that has not a share of being, and a difference should not be a part of the genus. If, however, substance could have a definition, setting aside the fact that it is the most universal genus, its definition will be: substance is the reality whose “whatness” ought not to exist in something. Hence, the definition of substance cannot be applied to God, whose “whatness” is not distinct from his own being. Therefore, God is not contained in the genus substance but is above all substance.

Reply Obj. 5: God cannot be defined. For whatsoever is defined is comprehended by the intellect of him that defines it; and God is incomprehensible to the intellect. Hence, it is not a definition of God when we say that he is pure act.

Reply Obj. 6: It is required by the account of a genus that it is predicated univocally. Now, nothing can be predicated univocally of God and created things, as we shall prove further on. (Q. 7, a. 7.) Therefore, although things predicated of God are predicated of him substantially, they are not predicated of him as genus.

Reply Obj. 7: Although God does not belong to the genus substance as though contained in the genus, as a species or an individual is contained in its genus; yet we may say that he is in the genus substance by reduction, as its principle, just as even a point is in the genus continuous quantity, and the unit in the genus number. In this way, he is the measure of all substances, as the unit is the measure of all numbers.