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The Necessity of Contingency, Part 3: Act and Potency

This is the third installment in the series stemming from my original post,The Necessity of Contingency.” You can view part two here. In the last post, I discussed the ontological presupposition behind classical theism, namely, man’s dependence. The goal of this post is to establish another foundational metaphysical presupposition of classical theism which will permit fuller discussion of causality, God’s knowledge, and human freedom in a later piece. What is laid out below is relatively basic but nevertheless essential to explaining how it is that the Reformed tradition conceives of God and human freedom. Much of what follows is basic Aristotelian philosophy. For readers familiar with the act-potency distinction in general, skip to the “Act, Potency, and Classical Theism” section below.

From Aristotle to Aquinas

The distinction between act and potency is the most fundamental metaphysical principle to which the Reformed scholastics of the seventeenth century subscribed, though there were debates as to how exactly the distinction should be interpreted (e.g. Thomists regard it as a real distinction whereas Scotists categorize it as a formal distinction). As Joshua Schendel has recently pointed out, there is some diversity of thought on these issues within the Reformed tradition. But most of the Reformed scholastics adopted a Thomistic formulation of act and potency even if they included some Scotistic modifications on other points.

Thomas Aquinas derived these basic principles of being (and they are that, principles; they do not subsist, nor are they intelligible, in themselves) from Aristotle. The Philosopher, as he was commonly called, developed the distinction in his Metaphysics to combat the then prevailing idea (of the Eleatics) that change is, in fact, impossible, since change (allegedly) would require being to arise from non-being. Since non-being is nothing and something cannot come from nothing, change, it was argued, was therefore impossible. On the other extreme was Heraclitus who believed that even temporary permanence was unattainable. All reality was perpetual becoming without being or stability. Aristotle argued against both extremes and held that whilst being certainly cannot arise from nothing, change was not being springing out of non-being, but rather one sort of being arising out of another sort of being.1

Aristotle’s insights were key for making sense of not only change and permanence, but multiplicity and unity. (on types of change, see Dolezal, 41-44). The Reformed did not adopted the Thomist view uncritically or without checking his work, so to speak. They too had access to Aristotle’s Metaphysics, but generally fell in line with Aquinas.2 

It is important to grasp this basic distinction for the sake of parsing questions of essence, substance, and causation (the latter being of primary interest in this whole series and the idea, as it relates to human freedom, at which I am eventually arriving).

Defining Act and Potency

Act and potency are metaphysical principles representing a complete division of being. Therefore, whatever exists is (pertaining to its intrinsic principles of being) either pure act or a composite of potency and act (since pure potency is to not exist).

What is meant by act and potency relates to states of being. There is being-in-act, the way a thing actually is; and there is being-in-potency, the way a thing could potentially be. It may be helpful, therefore, in order to get comfortable with the concepts to replace act with actuality (indeed, we will refer to God, who is pure act, as being pure actuality, having pure possession, of being) and potency with potentiality.

To illustrate this distinction, Edward Feser helpfully employs the instance of a rubber ball. In actuality, it is round, relatively solid, red, and also motionless. In potentiality it could be flat, squishy, pink or even white, and in motion. All of these potentialities are real features of the ball though not actualized. And so, the potencies (or potentialities) cannot be said to be nothing since the ball can become all of these things.

But for all of these potencies to become act, they must be acted upon in some way (e.g. the ball must be thrown by someone for the potency of motion to become actualized; it must be exposed to sunlight to become faded in color, etc.). Potencies require an extrinsic cause to be actualized. And potencies are, in a sense, derivative, or the correlative, of the act that the ball already possesses in that potencies are defined in relation to an act (i.e. the potential to become flat) and grounded in actualities (i.e. only a rubber ball, rather than a granite rock, can become squishy).

The potencies are not merely nothing because there is a referent actuality that gives rise to their potential. A ball, based on its actuality, cannot become, for example a sentient being, but it can become flattened. The actuality of its nature as a ball determines the range of potentialities. This is what’s known as a real potency, a potency grounded in the nature of real things as we know them, which is distinct from a logical potency which merely exists as an object of thought. The change that takes place in a ball moving from a stationary state to one of motion is not being arising from non-being but being-in-act arising from being-in-potency, or the actualization of potential.

For change to occur then, there must be the composite of act and potency, and for the potency to be realized, something (an efficient cause) must act upon the thing that possess them. As will be discussed more in the next post, an efficient cause is that which actualizes potency by the exercise of its own active potency (see below).

To be composite means that you possess potency and can receive further actuality of being. But you are not only potency, else you would not constitute a combination of act and potency. To be pure act, means that you lack potency and cannot receive further actuality of being (i.e. change) in any respect.

By way of an additional example, Charles J. Rennie refers to the slab of marble used by Michelangelo to sculpt David. The slab was being-in-act because it actually was a marble slab, but it was also being-in-potency with respect to the sculpture it could become (i.e. the likeness of David). This potential was actualized by Michelangelo.3  

The distinction between act and potency is applicable to any change, not just those relative to physical matter. It also encompasses both positive and negative change in states of being. To gain knowledge is to undergo change, for example, as is fluctuation in emotion. In the case of knowledge, when humans acquire knowledge, not only do they have something that they didn’t have before, but their entire state of being is affected thereby. In a very real sense, they are not the same being as they were prior to undergoing the acquisition of additional knowledge, which constitutes a change.  

Another helpful way of distinguishing between act and potency is to think of act as (metaphysical) perfection or completion and potency as the mere capacity for perfection. All things that exist possess some measure of perfection. I am fully human. That is a metaphysical perfection. But my accidents (e.g. hair length and color, height, weight, etc.) still possess potency without frustrating by basic form as human, the potency for which has been fully actualized at this juncture. Unfortunately, I appear to possess no further potency for taller stature.

In the Thomist formulation, act can only by limited by potency, so that where there is potency there is imperfection. When a thing possesses potency, it has the capacity to take on different forms and come to further actuality (perfection) of being.4

Types of Potency

An additional quick point is required. The scholastics weren’t satisfied with the simple distinction between act and potency. They often divided each aspect of the distinction into several types, which often yielded subtypes, and so forth.5 The important one to grasp for our purposes is the distinction between active and passive potency. The former refers to the capacity to bring about change or effect in something else. It is causal power. The latter is the capacity to receive change. As humans we possess both types of potency, but because we possess passive potency, when we exercise, so to speak, active potency, we are ourselves subject to change by the respective action. God, however, lacks passive potency and his active potency does not induce change in himself, though he can, obviously, bring about change in other beings. Pure (or uncreated) active potency such as this is simply implied in references to pure actuality.6

A Real Distinction

As alluded to above, Thomists conceive of act and potency as a real distinction because the difference between the two is said to exist in reality or in the objects (or substance) itself. It is not merely a virtual or formal distinction constructed in the mind. They are not identical. David Oderberg summarizes the neo-Aristotelian view or the real distinction well: “The only possible explanation for the fact that reality is able to take on new kinds of existence, whether substantial or accidental, is that there is some principle of potentiality inherent in reality.”7

It is necessary to affirm the real distinction in order to affirm that potency is grounded in actuality and to be able to say that there is something inherent in the rubber ball or a marble slab that gives it potential to change, but is limited in the range of possible change by the inherent nature of the substance (i.e. the David sculpture isn’t actually a living man). “In other words, the range of change that a thing may potentially undergo is determined and limited by the nature and mode of the thing that actually is.”8

To summarize some of the previous sections, “potency is the ability or capacity for a thing to become either substantially or accidentally different than it is. An entity is in potency to whatever perfections it can acquire but presently does not possess in actuality.”9 Another way of stating it is that “Being in potency is the condition of not really having, but being able to acquire, some perfection.”10 All created things exist in a state of being-in-act and being-in-potency according to different aspects. Since we exist, humans obviously possess some actuality, some perfection, of being. But because we change (i.e. mutability), we can receive further perfection, limited in range or scope by our present actuality. The presence of potentiality has a double-effect limitation. A thing that possesses potency is limited by the actuality the same thing already possesses, and it is limited by outside act(s) that are the catalyst for the actualization of potency. A thing that has both act and potency is both composite (not fully perfect; not pure actuality) and dependent, and it therefore cannot account for itself.

Act, Potency, and Classical Theism

Classical theism, and its assertion of divine simplicity in particular, heavily relies on the distinction between act and potency. For God to be absolute, perfect, independent, and simple he cannot be physically, logically, or metaphysically composite. Per James Dolezal, “Non-composition, it is argued, must characterize God inasmuch as every composite is a dependent thing that cannot account for its own existence or essence and stands in need of some composer outside itself… Furthermore, composition signifies the capacity of a thing to change or even be annihilated.”11

In contrast, humans are created, finite, and composite, and therefore caused and dependent beings. In the words of Aquinas, “[E]very composite has a cause for things in themselves different cannot unite unless something causes them to unite. But God is uncaused [and therefore independent] … since He is the first efficient cause.”12 Because of the implications of composition, proponents of classical theism are militant about insulating the being of God from predications involving composition.

Kinds of Composition

In the Summa, Aquinas describes six kinds of composition, all of which must be denied of God. But all the models of composition are really variations of the act-potency distinction. Remember that the very presence of act and potency constitutes composition, and that this applies to everything except God. Aquinas gives several reasons for denying all models of composition of God.13 The basic conclusion of the Angelic Doctor is that composition of any sort in God would frustrate his aseity, absoluteness, or independence (stated above) because composition necessarily implies dependence on a posterior cause and imperfection (i.e. the process of becoming).

Briefly, Aquinas first denies that God has bodily parts. Rather, he is pure spirit. The are detailed reasons for this, but Aquinas’ main reason for denying such is that scripture explicitly states that God is incorporeal (Lk. 24:39; 1 Tim. 1:17; John 4:24). Additionally, flesh and bones are matter and matter is created substance and therefore composite and contingent. It cannot be in motion unless put into motion (like the rubber ball). And, most importantly, bodily parts are perpetually (in fact, infinitely) in potency for division and necessarily distinct from the whole, which means that a unifying principle must put them together (i.e. dependency).

Aquinas does similar work on the distinction between matter and form, a denial of which in God is a necessary consequence of the denial of a body. Form is the principle of actuality for matter in that it supplies quiddity and character to matter, but form is not an essence in itself. If God were to be a composite of form and matter, he would owe his perfection to the form which would mean that his whole self, God as he is, is dependent for his perfection on something other than the fullness of his being.14

Since God is simple and identical to his nature, there cannot be in him a distinction between himself and his essential form. With humans, we are not identical to our form, but a mere instance or supposit of the form. Each of us participates in the form of humanity, but an individual instance of humanity is not identical with humanity itself.  The opposite is the case with God. Accordingly, Aquinas also denies that God participates in a genus or species and that there is any substance-accident composition in him. And most profoundly, Aquinas argues that God’s act of existence is identical to his essence. Stated differently, it is the essence of God to exist as the only necessary being (i.e. aseity). This last point, per Aquinas, is mainly because anything that has existence but is not existence itself has existence by participation in it and is therefore dependent. Since that cannot be the case with God, his essence and existence are identical.

Creator-Creature Distinction

To invoke Dolezal again, “a composite being is a creature.”15 Only ontologically contingent things are subject to composition. God cannot be the first efficient cause (or sufficient reason for creatures) if he is not pure act, if he were becoming rather than being itself. For God to be an appropriate object of worship, and for the claims of scripture to be true, he cannot be a creature, and therefore cannot be composite (and must lack potency).

This being the case, he cannot be affected by creatures in any respect, which necessarily includes his knowledge, power, and will. God cannot be induced from outside of himself to do anything. He cannot derive felicity or glory from anything but the inter-Trinitarian communion. And his knowledge cannot be increased (or decreased, for that matter) by the existence or actions of other beings. Jumping ahead to some content that will be taken up in the next post, God’s knowledge cannot be increased by the future (or present) actions of creatures. Likewise, his will and power cannot be affected by the same. God cannot react, which is why the Reformed would often refer to his will as arbitrary (but not in the contemporary sense).

This setup constitutes the most basic supposition of the creator-creature distinction. Indeed, it could be said that the entire driving force behind classical theism is to remove creaturely predications of God and highlight the difference between creator and creature, and the dependence of the latter on the former.

Act, Potency, and the Confessions

Many modern Reformed Christians will ask whether this distinction is represented in the Reformed confessional heritage. Of course, the two terms are not explicitly used. And in many treatments of the doctrine of God itself by Reformed theologians of ages past, the terms will not be found. This is because the act-potency distinction was a metaphysical presupposition. It was not thought to be necessary to fully explicate it every time the doctrines which depend on it were discussed. But this does not mean that the concepts are not there.

The Westminster Confession of Faith 2.1 says,

There is but one only, living, and true God, who is infinite in being and perfection, a most pure spirit, invisible, without body, parts, or passions, immutable, immense, eternal, incomprehensible, almighty, most wise, most holy, most free, most absolute, working all things according to the counsel of his own immutable and most righteous will, for his own glory, most loving, gracious, merciful, long-suffering, abundant in goodness and truth, forgiving iniquity, transgression, and sin; the rewarder of them that diligently seek him; and withal, most just, and terrible in his judgments, hating all sin, and who will by no means clear the guilty. 

There is a lot that could be unpacked in this article of the confession, but noteworthy for our purposes is the string of most’s. This is the confession’s way of communicating that God cannot be added to (or changed) regarding his attributes. Not only is he perfectly actualized in each of these attributes, he is those attributes.

Especially important is the affirmation that God is “without body, parts, or passions.” This means that God is not a composite being made of pieces. He was not and is not brought to further actuality of being by something outside of himself. He is “most absolute.” He is perfectly actualized. Why? Because he lacks passive potency; he is not a composite creature. He cannot be acted upon because he is actus purus.

It is interesting to note that the reference to “passions,” whilst certainly referring to the fact that God cannot undergo emotional change (because he has no potency) whatsoever, it has a broader meaning as well. In Aquinas’ Summa, he makes clear that “passions” (pati) can refer to any change.

Thirdly, in a wide sense a thing is said to be pati, from the very fact that what is in potentiality to something receives that to which it was in potentiality, without being deprived of anything. And accordingly, whatever passes from potentiality to act, may be said to be pati, even when it is perfected. And thus, with us, to understand is to be pati.16

An even more clear declaration of God’s pure actuality comes in 2.2 of the confession.

God hath all life, glory, goodness, blessedness, in and of himself; and is alone in and unto himself all-sufficient, not standing in need of any creatures which he hath made, nor deriving any glory from them, but only manifesting his own glory in, by, unto, and upon them.17

This is a robust statement of God’s independence, his aseity, his un-creatureliness, if you will. Not only is God uncaused in his being, he derives nothing from outside of himself. Not even his glory is properly added to. The confession does a good job of weaving all of these predications of God together to show their interdependence. If God is perfect, he is simple. If he is simple and perfect, he must also be immutable. If he is uncaused and independent (a se) he must be infinite and eternal, since an uncaused, perfect thing can have no beginning, and so on.

Concluding Thoughts

Mentioned earlier was the point that potency is grounded in actuality, and that actuality determines the type of potency a thing has. A rubber ball can’t become a man, but it can become flat. Likewise, a human being has the potency to grow in character and love, to have moments of compassion, and to acquire greater knowledge, etc. But man does not have potency to become those things themselves. His potency is limited by the nature of his actuality.

In the same vein, God actually is infinite, simple, immutable, and perfect. The nature of God’s actuality dictates what he is. Since he is pure act and utterly without passive potency (and not effected by his active potency), his actuality dictates that he cannot change; he cannot come to further actuality of being. If he were to have capacity or potency to grow in love, compassion, or knowledge, he would no longer be perfect, which would defy his actuality. This also means that his felicity cannot be displaced by suffering lest, again, he no longer be perfect. If God had any potency in any respect, he would cease to be perfect (metaphysically complete).

The bottom line is that there is no capacity in God for him to be anything other than what he already is. This gets us to the meaning of the title of James Dolezal’s book, All That is in God. If God possesses potency (or any other model of composition denied by Aquinas), and then necessarily relies on anything outside of himself for further actuality of being, all that is in God is not God, and whatever stands back of God with the power to provide him with further actuality of being, that thing should be our object of highest worship.

Having outlined this vital piece of the conceptual framework of classical theism, I will further discuss the Reformed understanding of causality and contingency vis-à-vis God’s knowledge and human freedom in the next installment of this series, and in so doing will refer back to principles of act and potency.


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Timon Cline

Timon Cline

Timon Cline is a graduate of Wright State University, Rutgers Law School, Westminster Theological Seminary. He also writes at Modern Reformation and works as an attorney in Philadelphia where he lives with his wife, Rachel.

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