Natural Theology deals with what can be known about the existence and nature of God by natural reason, apart from any supernatural revelation. According to classical theists such as Tomas Aquinas (1225-1274), all of the essential metaphysical attributes of God can be known by natural reason. This includes God's aseity, simplicity, immutability, eternality, unity, infinity, and morality.
Aseity (Self-Existence). Most classical theists see God's Aseity or Pure Existence as a key attribute. The early church fathers, as well as Augustine (354-430), Anselm (1033-1109), and Aquinas, continually cite the Bible in support of this position. In defending God's self-existence (aseity) classical theists such as Aquinas are fond of citing Exodus 3:14 where God identifies Himself to Moses as "I Am that I Am." This they understand to refer to God as Pure Being or Existence.
God is Pure Actuality, with no potentiality in His being whatsoever. Whatever has potentiality (potency) needs to be actualized or effected by another. And since God is the ultimate Cause, there is nothing Him to actualize any potential (i. e. ability) He may have. Nor can God actualize His own potential to exist, since this would mean He caused His own existence. But a self caused being is impossible, since it cannot create itself. Something has to exist before it can to do anything. Even God cannot lift Himself into being by His own ontological bootstraps. Thus, God must be Pure Actuality in His Being.
Of course, God has the potential to create other things. But He cannot bring Himself into being. He always was. And while God has the potential to do other things, He cannot be anything other than what He is. He has the power to create other things (active potency), but He does not have the power (passive potency) to exist in any other way than He does, namely, as an infinite, eternal, necessary, and simple Being.
God's aseity means that He is Being; everything else merely has being. God is Pure Actuality; all other things have both actuality and potentiality. Thus, God, cannot not exist. All creatures can be nonexistent. That is, they have the potentiality for nonexistence. Only God is a Necessary Being. All other beings are contingent.
Simplicty (Indivisibility). Since God is not composed in His Being, but is Pure Existence, Pure Actuality with no potentiality; it follows that He is simple and indivisible. A Being that by nature is not composed cannot be decomposed. One that has no parts cannot be torn apart. Hence, God has absolute simplicity with no possibility of being divided. He is literally indivisble.
Likewise, a God of Pure Actuality with no potentiality cannot be divided. For if it were divisible, then it would have the potential to be divided. But Pure Actuality has no potentiality in its Being whatsoever. Hence, it must be absolutely simple or indivisible.
God's indivisibility follows also from His immutability. For if God could be divided, He could change. But God is unchangeable by nature. Thus He cannot be divided. He must be absolutely simple in His nature.
Necessity (Noncontingency). God is by nature an absolutely necessary Being. That is, He cannot not exist. God is not a may-be but a must-be kind of Being. He is not contingent, since He does not have the possibility not to exist. If He has no potentiality not to exist, then He must exist.
This is not to say that the ontological argument is valid. Aquinas considered and rejected Anselm's proof for God. If God (i.e. Pure Actuality) exists, then He must exist necessarily. But one cannot simply define Him into existence. Aquinas offered his famous cosmological arguments for God's existence (Summa Theoligica, 1.2.3). And once we know, from reason and revelation , that God exists, then we can be sure that He must exist necessarily. Such a being has no potential not to exist.
Immutability (Unchangeability). In his epic Summa Theoligica (1a.9.1), Aquinas offers three basic arguments in favor of God's unchangeability. The first argument is passed on the fact that a God of Pure Actuality ("I-Am-ness") has no potentiality. It follows, therefore, that God cannot change (Exodus 3:14). Whatever changes has to have the potential to change. But as pure Actuality, God has no potential, so He cannot change.
The second argument for God's immutability follows from His simplicity. Everything that changes is composed of what changes and what does not change. God cannot change because an absolutely simple being has no composition. If everything about a being changed, then it would be an entirely new being. In fact, it would not be change but annihilation of one thing and a creation of something entirely new. Now if, in every change in a being something remains the same and something does not, then it must be composed of these two elements. So an absolutely simple being with no composition cannot change.
The third argument for God's unchangeability argues from His absolute perfection. Whatever changes acquires something new. But God cannot acquire anything new, since He could not be better or more complete. Therefore, God cannot change. If He did, He would not be God for He would have lacked some perfection.
Aquinas also argues that God alone is immutable (Summa Theologica, 1a.9.2). All creatures exist only because of the will of the Creator. His power brought them into existence, and it is His power that keeps them in existence. Therefore, if He withdrew His power they would cease to exist. Whatever can cease to exist is not immutable. Therefore, God alone is immutable; everything else could cease to exist.
Imassability (without Passions). A long-recognized attribute of God that has recently come under attack is impassability. God is without passions. Passion implies desire for what one does not have. But God, as an absolutely perfect Being, lacks nothing. To lack something He would have to have a potentiality to have it. But God is Pure Actuality with no potentiality whatsoever. Therefore, God is completely and infinitely satisfied in His own perfection.
However, to say that God is impassable in the sense that He has no passions or cravings for fulfillment is not to say that He has no feelings. God feels anger at sin and rejoices in righteousness. But God's feelings are unchanging. He always, unchangingly, feels the same sense of anger at sin. He never ceases to rejoice in goodness and righteousness. Thus, God has no changing passions, but He does have unchanging feelings.
Eternity (Nontemporality). God is not temporal (Summa Theologica, 1a. 10, 1). He is beyond time. Aquinas offers several arguments in support of this conclusion. The first argument goes:
1. Whatever exists in time can be computed according to its befores and afters.
2. Changeless being, as God is, has no befores or afters; it is always the same.
3. Consequently, God must be timeless.
Time is duration characterized by substantial and accidental changes. A substantial change is a change in what something is. An accidental change is a change in what something has. Growing knowledge is an accidental change in a being. Aquinas sees three levels of being in relation to time and eternity:
1. God is eternity is Pure Actuality, without essential or accidental change.
2. Angels and saints who dwell in the spiritual world of heaven live in aeviternity (or aevum).
3. Human beings, comprising soul and body, form and matter, live in time.
Eternity (God) endures without any potency. Aeviternity (angels) endure with completely actualized potency. Their changes are not essential but accidental. Spiritual beings in aviternity do not change in their essence, though they do undergo accidental changes. Angels increase in knowledge by divine infusion, and they have changableness with regard to choice, intelligence, affections and places (Summa Theologica, 1a.10.6). But with no substantial changes in aeviterny, angels are immutable in their level of grace and charity. What is true of the angels is also true of the elect in heaven.
Time (humanity) endures with progressive actualized potency.
The second argument for God's eternity similarly follows from immutability. It begins with the premise that whatever is immutable does not change in the state of its being. Whatever is in time goes through succession of states. So whatever is immutable is not temporable. This argument stresses another aspect of time; whatever is temporal has successive states, one after the other. God does not, so He is not temporal.
Total immutability necessarily implies eternity (Summa Theologica, 1a.10.2). For whatever changes substantially is in time and can be computed according to before and after. Whatever does not change cannot be in time, since it has no different states by which before and after can be computed. It never changes. Whatever does not change is not temporal. Not only is God eternal, but He alone is eternal (Summa Theologica, 1a.10.3), for He alone is essentially immutable.
Aquinas distinguishes eternity from endless time (Summa Theologica, 1a.10.4). First, whatever is essentially whole (eternity) is essentially different from what has parts (time). Eternity is now forever; time includes past, present, and future, now and then. The implication of this is that God's eternity is not divided; it is all present to Him in His eternal now. So it must be essentially different from time in successive moments.
Second, endless time is just more an elongation of time. But eternity differs qualitatively. It differs essentially, not merely accidentally. Eternity is an essential, changeless state of being that transcends moment-by-successive-moment reality. Time measures that reality, or rather the stage on which reality plays out.
Third, an eternal being cannot change, whereas time involves change. By change can measurements of before and after be made. Whatever can be computed according to before and after is not eternal. Endless time can be computed according to before and after. Hence, endless time is not the same as eternity. The eternal is changeless, but what can be computed by its before and after has changed. It follows, then, that the eternal now cannot live in relation to endless befores and afters.
Obviously, Aquinas saw a critical difference between the "now" of time, and the "now" of eternity. The now of time is moveable. The now of eternity is not moveable in any way. The eternal now is unchanging, but the now of time is ever changing. There is only an analogy between time and eternity; they cannot be the same. God's now has no past or future; time's now does.
Some has mistakenly concluded that Aquinas did not believe in God's duration for eternity, because he rejected temporality in God. Aquinas argued that duration occurs as long as actuality exists. But eternity, aeviternity, and time endure in different ways.
It follows, therefore that the essential difference in the quality of the duration in time, aeviternity, and eternity comes from the condition of the actuality. God is Pure Actuality. Angels have received total actuality from God in their created spiritual forms. Human beings progressively receive actuality in both spiritual form and material body.
Since God endures without potentiality, He cannot endure progressively. He endures in a much higher way -as Pure Actuality.
Immensity. Along with eternity is the attribute of immensity (nonspatiality). God is not limited in time, nor is He limited in space. In God's immanence He fills space, but He is not spatial. Only material things exist in space and time, and God is not material. "God is a spirit" (John 4:24). As spiritual, God is not material or spatial. It is part of God's transcendence that He is beyond both time and space.
Unity. Classical theists have offered three reasons for God's unity (Summa Theologica, 1a.11.3). The first argument is from the simplicity of God. An absolutely simple being cannot be more than one, since to be more than one there must be parts, but simple beings have no parts. Absolutely simple beings have no parts. Absolutely simple beings are not divisible. God is an absolutely simple being. Therefore, God cannot be more than one being.
God's perfection argues for His unity. If two or more gods existed, they would have to differ. In order to differ, one must have what the other lacks. But an absolutely perfect being cannot lack anything. Therefore, there can only be one absolutely perfect being. God's unity also can be inferred from the unity of the world. The world is composed of diverse things. Diverse things do not come together unless they are ordered. But the world has ordered unity. Therefore, there must be one Orderer of the world.
Theists argue that essential unity is better explained by one Orderer than by many orderers. For one is the essential cause of oneness, but many is only the accidental cause of oneness. Therefore, it is reasonable to infer that there is only one cause of the world, not many.
Relatability (to the World). One criticism of classical theism is that an eternal, unchanging God could not relate to a changing world. Aquinas anticipated this objection and treated it extensively.
There are three kinds of relations: One where both terms are ideas; one where both terms are real; and one where one term is real and one is an idea (Summa Theologica, 1a.13.7).
Now since creatures are dependent on God but God is not dependent on them, they are related as real to an idea. That is, God knows about the relationship of dependence but He does not have it. When there is a change in the creature there is no change in God. Just as when the man changes his position from one side of the pillar to the other, the pillar does not change; only the man changes in relation to the pillar. So, while the relationship between God and creatures is real, God is in no sense dependent in that relationship.
Aquinas is only denying dependent relationships, not all real ones. God never changes as He relates to the world, but real changes do occur in that relation with the world. The man's relation to the pillar really changes when he moves, but the pillar does not change.
The real but unchanging relation of God to the world is made even more clear when Aquinas considers how the eternal God relates to a temporal world (Summa Theologica, 1a13.7, ad 2). God condescends to relate to humans as if He shared time with them. He can create a temporal relation that in no way changes Him. Eternity can move in time, though time cannot move in eternity. To have a relationship with the temporal world, God does not have to be temporal. It makes no more sense to say God has to be temporal in order to relate to a temporal world than to say He has to be a creature in order to create.
God is really related to creatures as their Creator. But creatures are really related to God only because He is their Creator. They are dependent on that Creator-creature bond, He is not. Therefore, the relation of God to creatures is real and not merely ideal. However, it is a real relationship of dependence on the part of the creatures but not a relation of dependence on the part of God (Summa Theologica, 1a.13.7, ad 5).
God's Knowledge. God knows Himself. If God is absolutely simple, can He know Himself? All knowledge involves both a knower and a known. But God has no such duality. Aquinas argues that in self-knowledge the knower and known are identical. Hence, God can only know Himself through Himself (Summa Theologica, 1a.14.2). Since God is simple. He knows Himself simply.
God also knows Himself perfectly. Something is known perfectly when its potential to be known is completely realized. And there is no unactualized potentiality to know Himself. Therefore, God's self-knowledge is completely actualized (Summa Theologica, 1a.14.3).
God's knowledge is identical with His essence. For if God's acts of knowledge were really distinct from His essence, then they would be related as actuality to potentiality. But there can be no potentiality in God. Therefore, God's knowledge and essence are really identical (Summa Theologica, 1a.14.4). This does not mean that God cannot know things other than Himself. For God is the efficient cause of all things.
God Knows and Does. Even though God knows other things than Himself, nonetheless, He knows then through Himself. For God does not know other things Himself either successively or inferentially but simultaneously and intuitively (Summa Theologica, 1a. 17.7, ad 2). God's knowledge is more perfect because He does not have to know things discursively through their causes but knows them directly and intuitively (Summa Theologica, 1a.14.7 ad 3,4). God not only knows all things in and through Himself, but He also causes all things by His knowledge. God causes all things by His being, but God's being and His knowledge are identical (Summa Theologica, 1a.14.8). This does not mean that creation is eternal because He is eternal. For God causes all things as they are in His knowledge. But that creation should be eternal was not in God's knowledge (Summa Theologica, 1a.14.8, ad 2).
An effect pre-exists in the mind of its efficient cause. Hence, whatever exists must pre-exist in God, who is its efficient cause. God knows all of the various kinds of perfection in Himself, as well as those which participate in His likeness. Therefore, God knows whatever exists perfectly, insofar as it pre-exists in Him (Summa Theologica, 1a.14.5).
God Knows Every Creature Ideally. God knows His own essence perfectly. And knowing His essence perfectly entails knowing it according to every mode by which it can be known, namely, in itself and as participated in by creatures. But every creature has its own proper form, in which it is like God. It follows, therefore, that God knows the form or idea of every creature as it is modeled after Him. Perfect knowledge involves the ability to distinguish one thing from another. That is, He knows not only what things have in common (esse) but how they differ (essence). Therefore, God knows all things in their individual essences. But all things pre-exist in God's knowledge. Therefore, all things pre-exist in God's knowledge, not only with regard to their existence but also with regard to their individual essences.
The basis for what God knows is His own essence, but the extent of what He knows is not limited to that one essence but reaches to all things like it (Summa Theologica, 1a.15.2). God's knowledge of all things in Himself does not mean that He only knows other things in general but not in particular. For God's knowledge extends as far as does His causality. And God's causality extends to singular things, since He is the cause of every individual thing. Therefore, God knows singular things (Summa Theologica, 1a.14.11). God has a perfect knowledge of everything. And to know something only in general but not in particular is improper knowledge. So, God knows everything properly. That is, He does not know the radii of circles merely by knowing the center; He knows the radii as well as the center.
God Knows Evil. For perfect knowledge of things must include knowing all that can occur to them. Evil can occur as a corruption of good things. Hence, God can know evil. But things are knowable in a way in which they exist. Evil is a privation in good things. Therefore, God knows evil as a privation in a good (Summa Theologica, 1a.14.10).
God Knows Changing Things. Since God is unchanging and His knowledge is identical with His essence, He knows past, present, and future in one eternal now. Therefore, when time changes, God's knowledge does not change, since He knew it in advance. God knows change, but not in the way we know it, in successive time frames. From eternity God knows the whole of before and after the temporal now of human history (Summa Theologica, 1a.14.15).
God knows the same things we do, but He does not know them the same way we know them. Our knowledge is discursive, moving from premises to conclusions. In human knowledge there is twofold discursiveness: One thing is known after another, and one thing is known through another. But God cannot know things sequentially, since He is timeless and knows all things eternally at once. Nor can God know things inferentially, for He is simple and knows all things through the oneness of Himself. Therefore, God cannot know anything discursively (sequentially, from topic to topic), inasmuch as discursive knowledge implies a limitation to consider one thing at a time on the part of the knower (Summa Theologica, 1a.14.7).
God Knows All Possibilities. By knowing Himself perfectly God knows perfectly all the different ways His perfections can be shared by others. For there is within the essence of God all the knowledge of all the possible kinds of things His will could actualize. Hence, God knows all the particular things that could ever be actualized (Summa Theologica, 1a.14.6).
God's Knowledge Allows Free Will. Pulling these strands of thought about God's knowledge together shows us how God's sovereignty works alongside human free will. God's knowledge is not simply of the actual; He also knows all possible sorts of potential. He knows what is and what ever could be. For God knows whatever is in any way it can be known. Now both the actual and the potential are real. Only the impossible has no reality. Thus, whatever is potential is real. It follows that God can know what is potential as well as what is actual (Summa Theologica, 1a.14.9).
This means that God can know future contingents, that is, things that are dependent on free choice. For the future is a potential that pre-exists in God. And God knows whatever exists in Himself as the cause of those things (Summa Theologica, 1a.14.13). Since God is a timeless being, He knows all of time in one eternal now. But the future is part of time. Therefore, God knows the future, including the free acts performed in it. Of course, whatever God knows is known infallibly, since God cannot err in His knowledge. Future contingents are known infallibly. They are contingent with regard to their immediate cause (human free choice) but necessary with regard to God's knowledge. God can do this without eliminating free choice, for an omniscient being can know whatever is not impossible to know. And it is not impossible for a timeless being to know a necessary end caused by a contingent means. God can know a must-be through a may-be but not a can't-be.
Therefore, an omniscient Being knows future actions as necessarily true events. If an action will occur and God knows it, then that event must occur, for an omniscient Mind cannot be wrong about what it knows. Therefore the statement "Everything known by God must necessarily be" is true if it refers to the statement of the truth of God's knowledge, but it is false if it refers to the necessity of the contingent events (Summa Theologica, 1a.14.5).
God's Will. Will can be defined as a being's rational inclination toward its own good. Whatever has intellect also has will, for will follows upon intellect. Further, every nature inclines to its own proper end or good. When the end is rational then the inclination is a rational inclination. God has rational inclination toward the good of His own nature. Therefore, God has will (Summa Theologica, 1a.19.1).
Having will does not mean that God changes. For the object of God's will is His divine Goodness. And whatever is in oneself necessitates no movement outside oneself to attain. Hence, God does not have to move outside Himself to attain His proper end. And will is an inclination toward one's own end. So, there is will in God, inasmuch as He inclines toward His own good. Will also involves love and delight in what is possessed. God loves and delights in the possession of His own nature. Therefore, God has will in the sense of delight but not in the sense of desire. (Summa Theologica, 1a.19.1).
God's Will Causes Things to Be. Simple because God wills things only in Himself does not mean that He wills only Himself. For it is in accord with the nature of being to communicate its good to others. And God is being par excellence; He is the source of all being. Hence, it is in accord with the nature of God to will other beings than Himself (Summa Theologica, 1a.19.2). So God wills things other than Himself in and through Himself. God is not other than Himself, but He can will things other than Himself in Himself. For will implies a relationship. Hence, although God is not other than Himself, yet He wills things other than Himself (Summa Theologica, 1a.19.2, ad 1).
God is not moved by anything outside of Himself when He wills to create through Himself (Summa Theologica, 1a.19.2, ad 2). But in willing things other than Himself, God is not moved by any insufficiency in Himself but by the sufficiency in Himself, that is by His own goodness. Therefore, willing other things through His own sufficiency denotes no insufficiency in God (Summa Theologica, 1a.19.2, ad 3). Just as God knows many things through the oneness of His essence, He can will many things through the oneness (good) of His will (Summa Theologica, 1a.19.2 ad 4).
God Must Will and Can Will. God wills things in two ways. Some things -His own righteousness, for example -He must will. He cannot choose to will otherwise. These things He wills with absolute necessity. Other things God wills with conditional necessity -the righteousness of creatures, for example. Whatever is willed by conditional necessity is not absolutely necessary. Creation is willed by conditional necessity.
Of course, God wills other things because of His own righteousness but not as necessitated by it. For God can exist without willing other things. God need only will His own righteousness necessarily and other things contingently. Therefore, these other things need not be willed with absolute necessity. Of course, it is necessary to God's will that He will His own nature necessarily. But God need not will anything other than Himself. When God did will things other than Himself, He must have willed these things voluntarily (Summa Theologica, 1a.19.3, ad 3).
It would seem that God must will things necessarily. As a Necessary Being He must know necessarily whatever He knows. It would seem then that He must will necessarily what He wills.
Aquinas responds that divine knowing is necessarily related to the created thing known, because the knowledge in the Knower is one with His essence. But divine willing is not necessarily related to the created thing willed. Willing relates to things to things as they exist in themselves, outside of the divine essence. God knows necessarily what He knows but does not will necessarily what He wills. Further, all things exist necessarily in God, but nothing exists necessarily outside of Him. But God need only will what is necessarily of His own nature. Therefore, God need only will other things as they exist in Him but not as they exist in themselves outside of Himself (Summa Theologica, 1a.19.3).
All Created Effects Pre-exist in God's Will. God's will is the cause of all things, so all created things pre-exist in God's knowledge. Will is the inclination to put into action what one knows. Therefore, all created effects flow from God's will (Summa Theologica, 1a.19.4). Of course, God must bestow good on all He chooses to create; God cannot create evil. But it is not necessary that God should will any other being or good than Himself. Therefore, God need only bestow good on what He chooses to create (Summa Theologica, 1a.14.4, ad 1).
God's Will Is Uncaused. As to whether God's will is caused, Aquinas says that, rather, God's will is the cause of all things. What is the cause needs no cause. For in God the means and the end pre-exist in the cause as willed together. Human will looks to a desired end and what may be done to reach the goal. God's will causes both the end willed and the means to that end. And since all things pre-exist in the First Cause (God's will), there is no cause for God's will (Summa Theologica, 1a.19.5).
God's Will Can Never Fail. The will of God is the universal cause of all things. Therefore, the will of God is always fulfilled. What fails to accomplish God's will in one order does so in another order. For example, what falls from the order of His favor returns to the order of His justice. When particular causes fail, the universal cause does not fail. God cannot fail (Summa Theologica, 1a.19.6).
One may speak of an antecedent and consequent will of God. God wills antecedently that all should be saved (2 Peter 3:9). But God wills consequently that some will be lost, namely, those whom justice demands. But what is willed antecedently is not willed absolutely but conditionally. Only the consequent is willed is willed absolutely in view of all the circumstances. Of course, God wills some things through secondary causes. And first causes are sometimes hindered through defects in secondary causes. The movement of the body is hindered by a bad leg. Likewise, God's antecedent will is sometimes hindered by a defect in a secondary cause. But His consequent will is never frustrated. For first universal causes cannot be hindered by defective secondary causes, anymore than righteousness can be hindered by evil. However, God is the universal first cause of being, and His will cannot be hindered in His causing being (Summa Theologica, 1a.19.6, ad 2).
God Does Not Change His Mind. Neither can God's will be changed, for God's will is in perfect accord with His knowledge. He is omniscient, so what He knows will be, will be. Therefore, God's will is unchangeable. This does not mean that God does not will that some things change. But God's will does not change, even though He does will that other things change (Summa Theologica, 1a.19.7). When the Bible speaks of God "repenting," it means that from where we stand it looks as if He has changed His mind. God knew from eternity how it would fall out. And God's will includes intermediate causes, such as human free-will. So God knows what the intermediate causes will choose to do. And God's will is in accord with His unchangeable knowledge. Therefore, God's will never changes, since He wills what He knows will happen. What is willed by conditional necessity does not violate human freedom, since what is willed is conditioned on their freely choosing it. God wills the salvation of human beings conditionally. Therefore, God's will to salvation does not violate human free choice, but uses it.
Sources
Augustine, The City of God
S. Charnock, Discourse upon the Existence and Attributes
of God
R. Garriguou-LaGrange, God: His Existence and His Nature
N.L. Geisler, Philosophy of Religion
Thomas Aquinas, Summa contra Gentiles, Summa Theologica
From the Encyclopedia of Christian Apologetics
(ISBN 0-8010-2151-0)