Q. 3 “Of the Simplicity of God”
As it is, Thomas thinks that his five proofs for God’s existence have hardly proven much. They have shown that God is (1) an unmoved mover, (2) an uncaused first cause, (3) a necessary being, (4) a perfect being, and (5) an intelligent, ordering being. Should you feel that this isn’t much to go on, let it be known that Thomas is in complete agreement. (Compare Augustine in the Confessions: saturated with a knowledge of who God is, he struggles to arrive at a philosophically satisfactory understanding of what God is.) So far we have only shown that God exists; we still don’t have a clue as to what, much less who, he is. Nor, as it turns out, does Thomas even think that we can know what God is in this life. As Thomas writes in the prologue of the very next question, question three on God’s simplicity, “because we cannot know what God is, but rather what he is not, we have no means for considering how God is, but rather how he is not.” Don’t let all the philosophical proofs in the Summa fool you: after proving (by philosophical reason) that God, understood as some super-nebulous, powerful thing, does in fact exist, Thomas basically goes agnostic. What this means is that the rest of Thomas’s treatise on God, with its otherwise philosophical treatment of such traditional divine attributes as divine simplicity, goodness, unity, eternality, infinity, immutability, and so forth, is put forward by St. Thomas as a lengthy exercise, not of using reason to determine what God is, but precisely of what God is not. This is negative theology, Thomistic style: if you say what God isn’t a sufficient number of even times, it turns out to be something positive. The role of Thomas’s natural theology, accordingly, at least as he understands it, far from making God comprehensible and perspicuous to the finite human intellect, is rather to persuade the human mind of the utter mystery and transcendence of God. Natural theology is always negative theology: to know what God is by the natural light of human reason is only ever to know what God is not. Again, if you want to know God, you’re going to need revelation.
The third question of the Summa asks whether God is simple, by which Thomas means whether God is not complex or composed of parts (again, we see God’s attributes being defined negatively). Thus, turning to the first article of the third question on divine simplicity, we find Thomas asking if God is a body, the answer to which is that he is not (bodies are always composed of, and thus are divisible into, smaller parts). In article two he asks if God is composed of form and matter, the answer to which is that he is not. In article three, however, things become a little more difficult, as Thomas asks if God is identical with his own essence or nature. The essence or nature of a thing identifies what kind of thing a particular being is. As a consequence, you might say that a thing’s essence is something that transcends the thing itself and hence determines the kind of thing that it is. The essence of dogness, for example, transcends (not literally, as in the fashion of Plato’s forms) any individual dog, which is to say that the idea or reality of dogness is always something greater than any individual dog: no particular dog is able to exhaust what it means to be a dog, or put in more Thomistic terms, no dog is identical to the essence of dog, otherwise there would be no “room,” so to speak, for other dogs to exercise their dogness. This cannot be the case for God, however, who isn’t God because he merely happens to “fall into” a more overarching, encompassing category of “godness.” For Aquinas, not only is it the case that there are no other gods besides the one true God, but there can’t be any gods besides him either. The reason for this is because the “category” of god, if you will, isn’t something other than God himself: God is not only God, but he is also what it means to be God. He not only is what he is, but he also defines what he is: he is one with his definition. Nothing stands outside God measuring, defining, or otherwise determining him. And Thomas’s way of saying this is to say that God is one with or identical with his essence.
However, according to Aquinas God is not the only being who is identical with his essence, for he believes this is true of the angels as well: no angel is identical in essence or species to any other angel, making every angel radically unique and sui generis. It is thus in the following fourth article of the third question that Thomas makes one of his most radical, famous, and difficult of claims. Granted that God, like the angels, is identical with and not distinct from his own essence, can it be further said that God, unlike the angels, is also identical with his own act of existence? Or as Thomas himself puts the question, are “essence and existence the same in God?” This is where Thomas’s true metaphysical revolution takes place, where he gets real metaphysical “lift off.” In the first three articles, after all, Thomas says nothing all that new. Here, however, he makes the jump to light speed. If you can get a handle on what Thomas does here, and why it is important, you will have understood what is perhaps the most important thought that Thomas felt he ever had.
One way to get our minds around this claim is to see Thomas as trying to synthesize not only Christianity with Aristotle, but indeed, even Plato with Aristotle. (This reminds us of the oversimplification involved in pitting Christian theology over against “pagan philosophy,” monolithically conceived, for as the case of St. Thomas would indicate, it is only through the lens of Christian theology, that great reconciler of men, that pagan philosophy can even be made to agree with itself.) On Plato’s ontology, we recall, the physical world is composed of corporeal, sensible objects which participate for their being in a transcendent, separated, intelligible realm of the forms. Aristotle, by contrast, while retaining Plato’s form-matter distinction, nevertheless revised Plato’s ontology by making the forms integral to and immanent within, rather than extrinsic to the things themselves. According to Aristotle, therefore, individual substances are composed of form and matter. It is the differing degree to which the matter in a thing is assimilated or conformed to its form, moreover, that determines where a thing is in the great hierarchy of being. The more a given form, in other words, determines, organizes, or “gathers up” the matter in a thing, the more being that thing will have. Thus, a rock, for example, that retains its “form of rockness” is more of a rock than one that easily crumbles into pieces (its “potentiality” for being a rock is more “actualized”). The same thing is true when we compare different species with each other. No matter how good a given rock is at being a rock, as a rock it’s never going to have as much form (which is to say, as much actuality, dynamism, order, and therefore being) as may be found in even the simplest plant (the more complex a thing, the more “form” or actuality it has—the more it has “going for it,” metaphysically speaking). Above both inanimate objects and vegetable life, however, are animals with the power of sensation, which demonstrates overall an even greater purchase power of form over matter, of actuality over potentiality. (Think about it: although physical sight, for example, is just as much a material process as one rock crashing into another, the level of sophistication and subtlety—which is to say, of form—of the former is far, far greater. Indeed, for Aristotle, in physical sight you have form taking hold over and utterly transforming matter to such a degree that, even more than the other four senses, it is the closest thing in the material realm that you have to a purely spiritual and hence immaterial process and phenomenon.) Above sensible animals in this process of form’s domination over matter are human beings, who exercise the power of intelligence and reason, powers which in fact make use of no physical organ whatsoever but are purely immaterial and incorporeal activities (and who, incidentally, use their powers of intelligence and reason to transform their environment in a way far exceeding that found in any lower beings). Finally, above man further still are, for Aristotle, the gods, who having no matter at all, have no unactualized potentiality whatsoever, but are pure form, pure essence. Aristotle thus describes the Unmoved Mover as “self-thinking thought”: as pure form, pure thought, it thinks only that which is itself pure form or thought, namely itself.
In review, then, it is the dialectical interplay between form and matter, potentiality and actuality, that defines Aristotle’s universe: the more matter/potentiality a thing has, the lower it is in the hierarchy of being; the more form/actuality it has, the higher it will be. And St. Thomas, it should be said, agrees entirely with this analysis: this is how God, he believes, has made the world. But in making this latter observation, one has effectively introduced a distinction between Aristotle and St. Thomas as important as anything they held in common: Thomas’s world is created and Aristotle’s is not, and this leads St. Thomas to ask questions that Aristotle never thought to ask, and indeed, to apply Aristotle’s own potentiality/actuality distinction in ways Aristotle never thought to apply it. For consider this: once you have posited Aristotle’s hierarchy of substances, ranging from the inanimate stone to the transcendent self-thinking thought of the unmoved mover, and all differing from each other according to their proportion of actuality to potentiality, despite the radical differences measured by this scale, what can you nevertheless say that everything on Aristotle’s hierarchy still has in common? They may all exist in different ways, but they all exist. Being is something they all “have,” something they all “share.” Now, because Aristotle believed the universe, including his hierarchy, to be eternal, he ended up taking this seemingly obvious point for granted. Sure, to account for a thing you must identify the matter it’s made out of (material cause), what kind of thing it is (its form), the agent(s) responsible for this matter coming to have this form (efficient cause), and the purpose or goal that the thing is existing for (final cause). What Aristotle failed to include in his reckoning, however, was the sheer fact of existence itself. And this is where we can see Thomas, under the influence of the Christian doctrine of creation, attempting to bring Plato back into the picture. You see, the problem with Aristotle is that in tracing the form/matter distinction all the way up the hierarchy of being until it reached its upper threshold in man, Aristotle thought he had also exhausted the actuality/potentiality distinction. Once we reach a level of being, namely the gods, in which there is no matter, we no longer have any potentiality either, right? Wrong. What Aquinas saw (and here the Christian doctrine of creation was not only crucial, but also the Christian doctrine of the angels) was that you could have a completely immaterial being (in Thomas’s case, an angel) that nevertheless was not pure actuality, but still had some remaining potentiality, namely its potentiality, if for nothing else, then at least for existence itself. In such a being, even if there was no distinction between form and matter (since there is no matter in angels, according to Aquinas), one could nevertheless distinguish between its form and its actual existence, between what a thing is and that a thing is. What this means is that the actuality/potentiality distinction of Aristotle doesn’t quite run out or reach the end of its tether when the form/matter distinction does, but in fact can be traced all the way up Aristotle’s hierarchy, even to the level of the gods (the fact that Aristotle was unsure how many gods there were is indication in itself that, even if it is necessary that at least one or more gods exist, no one of these gods is necessary as such). The actuality/potentiality distinction, therefore, is not coextensive or coterminous with the form/matter distinction. Thus, even in the case of Aristotle’s gods we can ask what efficient cause is responsible for giving existence itself to his gods. More generally still, even after we have let Aristotle have his say in terms of analyzing all the explanatory causes that are immanent, intrinsic, or integral to a bodily substance, we still have to step back and give an account of the cause of existence itself. Using the participation language of Plato, therefore, Thomas argues (in article four of question 3) that things exist by virtue of participating in that which is Existence Itself (ipsum esse se subsistens), and that Existence Itself is God.
As for God himself, Thomas’s argument is not simply that God has being, as though God were one thing and his being or existence something else, but that God simply is being. God is being essentially, whereas all other entities have being only by “participation,” by participating, that is, in God who is the “form” of being, if you will. God is Being, existence itself, divine esse. As one might recall from the Confessions, Augustine also said this, and what he primarily meant by it was that God was unchanging. For Thomas, God is being, which means he is pure, undiluted, unadulterated, unlimited or unconstrained act, actuality, actualization, activation. He is the act of all acts, he is the act behind all acts, he is the one who gives actuality its actuality; he is not simply perfection, he is the perfection of all perfections. He is the one who makes perfection to be perfect. This is what it means when Thomas says that God’s essence is his existence.
Having proven that God is existence itself, self-subsisting being (ipsum esse se subsistens), Thomas spends the next several questions teasing out what that exactly means (cp. Anselm’s Proslogion, which deduces the attributes of God from his being “that which nothing greater can be thought”).