Act, potency, and other preliminary remarks

The notions of act and potency have their origin within Aristotle's philosophy of nature. For change to be a real feature of the world and to avoid the Parmenidean challenge, Aristotle posited a real difference between two kinds or modes of being: being-in-act and being-in-potency. The first relates to what a given thing is here and now, simpliciter (a fertilized chicken egg, for instance); the second relates to what a thing can be (a grown adult chicken). Everything in the natural and changing world of experience thus becomes a metaphysical mixture or composite of act and potency, being in act in some respects and in potency in others, being actually some thing or other and potentially many other things. A bowl of microwaved soup is actually hot but potentially cold, it is actually in my table but potentially in my stomach (and also on the floor). What change amounts to, then, is for a potency to become actualized.

Now, within the Aristotelian tradition, act has always been considered to be more fundamental or primary than potency. It is not just that for any given potency or potential to become actual it needs to be actualized (i.e. receive actuality) from something already actual, but especially that potency could not exist purely by itself, separately, so to speak. There cannot be something that is pure potentiality, without being actual in any respect. For some separate thing or substance to be purely potential, it would have to be nothing in particular, but no thing can be absolutely nothing. On the contrary, if something exists, it has to be something. Hence, potency is always parasitic with respect to act: it can only have reality as a feature of some actual thing. In other words, potentiality is dependent on and is grounded in actuality.

The same is not true, however, in reverse. While no thing could be purely potential without being actual in any respect whatsoever, there could be something, at least in principle, that is purely actual without being in potency in any respect whatsoever. To such purely actual reality, classical or pure-act theism has traditionally given the name ‘God’, claiming it to be the unconditioned, unlimited, ultimate, and absolutely necessary foundation of everything else that is.Footnote ¹ Such would be Aquinas's esse tantum or Ipsum Esse Subsistens: the pure act of being itself.

It is not my aim in this article to substantiate any of these theses, nor to defend any of the traditional arguments (or ‘proofs’) through which classical theists have claimed to establish the existence of such a purely actual foundational reality to which omnes dicunt Deum.Footnote ² What I would like to propose instead is that, precisely because of its picture of God as a purely actual first cause of things, pure-act theism has a significant advantage over one of the major rival naturalistic theories of the First Cause, that which comes from Graham Oppy. This advantage can be argued for in two parallel and non-exclusive ways: one where causal finitism is granted (and where, as a consequence, we have strong reason to believe that there is some kind of First Cause in the distant past history of things), and another one where a foundational layer of reality is granted.

Given that the argument of this article has as its starting point the existence of a First Cause, and from there tries to elucidate its nature, pointing to a reason to think that it has to be purely actual, it belongs to the purview of the so-called ‘Gap Problem’. Though a crucial part of traditional natural theology, this is an under-researched area in contemporary philosophy of religion and deserves more attention.

As for Graham Oppy, many consider him (rightly, in my opinion) one of the most engaging and thought-provoking contemporary naturalists.Footnote ³ Additionally, he has engaged several times with both traditional and contemporary defenders of classical theism (Oppy (Reference Oppy and Marenbon2012), 687–704 and (Reference Oppy2021)). And, as we will see, he takes seriously the hypothesis of a First Cause, seemingly leaning towards it and providing one of the most fleshed-out naturalistic accounts of it. That classical theism, then, should have a significant advantage as a theory of the First Cause over such a strong naturalistic proposal may be taken as powerful evidence in its favour. Admittedly, more work should be done to see whether classical theism has this advantage over all possible naturalistic alternatives, so this will remain open for future investigation.

The argument with causal finitism

Causal finitism is the thesis that nothing can have an infinite causal history – that it is metaphysically impossible for something to be preceded by an infinite number of causes. As such, it has been masterfully defended by Pruss (Reference Pruss2018a).Footnote ⁴ What matters for us here is that, if causal finitism is true (and granted that something has a cause), then it follows that there is an ultimate uncaused cause, or in other words, a First Cause. Let's assume for the purposes of this article that causal finitism is in fact true and that, hence, we have the best of reasons to think that there is indeed a First Cause.Footnote ⁵ Now, per Alexander Pruss's own admission (Pruss (Reference Pruss2018b), 3), causal finitism is silent as to the number of entities making up its implied ‘First Cause’ (as well as to its nature). For all it tells us, the First Cause could be a plurality of things or items, and so ‘First Cause’ should be taken as a stipulated expression that is neutral with respect to this point. Hence, causal finitism as such does not commit us to any particular account of the First Cause, being in principle compatible with both theism and naturalism, but also even with polytheism. In other words, while if causal finitism is true, we know that there has to be a First Cause,Footnote ⁶ what we do not know is how many First Causes there are.

Granting, then, causal finitism, let's ask ourselves such a question: How many First Causes are there? Before trying to answer it, we should notice that any attempted response would raise an even further question. Imagine we were to say that there are exactly 47 First Causes, or 55, or 10⁸⁰. The next question we would naturally want to know the answer to would be: why are there 47/55/10 ⁸⁰ First Causes? And notice that whatever answer one were to give to this second question, it could not be one involving a causal explanation, since we are talking here about the First Cause. If there were to be a cause that explained why there are exactly that many First Causes, then we would not be speaking of the First Cause in the first place. Instead, the First Cause would be that which explained such a thing, and given causal finitism's indeterminacy in this respect, we would still want to know how many entities made up this newly hypothesized First Cause, and why.

So there cannot be a causal explanation of the number of First Causes, precisely because we are speaking ex hypothesi of the First Cause. Any purported answer to the question of why there are that many First Causes – no more and no less – would have to be either (a) that it's a brute fact with no explanation, or (b) that it's a necessary fact that could not have been otherwise. And I take it that, when possible, (b) is to be preferred to (a), even if one were not to grant the PSR.Footnote ⁷

Also, and to take things a little further, it is widely acknowledged that, due to Ockham's Razor, out of two equally explanatorily efficacious accounts, we should prefer that which posits fewer entities and is, hence, simpler. So, ceteris paribus, a theory which posited 47 First Causes should be preferred to one which posited 55 or 10⁸⁰, and one which posited a finite number of First Causes to one which posited an infinite number of them.Footnote ⁸

Taking all these points into account, the advantage I want to ascribe to the pure-act theist's candidate for a First Cause is that, by adopting it, we are able to (1) get an answer to the question of how many First Causes there are; (2) explain why there is that number rather than another (namely, as we'll see below, because there can be no other) and (3) such a number could not possibly be lower.

(1) and (3) are fairly obvious. To the question ‘How many First Causes are there?’, the classical theist answers ‘One’, giving thus the simplest possible answer to the question.Footnote ⁹ But what is the rationale behind (2)? Why is it that there is one and only one purely actual First Cause? To this, the classical theist responds that there is one and only one purely actual First Cause because there can only be one purely actual thing. In other words, it is because a purely actual thing is not susceptible of multiplication.

The arguments for this conclusion are well known from the tradition.Footnote ¹⁰ Given Aquinas's metaphysics of being (esse), and how it relates to essence as act to potency, a purely actual reality would have to be pure being itself (Ipsum Esse Subsistens) – instead of having an essence really distinct from its esse, its essence would just be pure esse itself. But then, such a thing could not be multipliable, because it could not be subjected to any differentiating feature, as a genus (animal) is multiplied in its species (human) by the addition of a specific difference (rationality) or a species (human) in its individuals (Peter, Mary, and James) by the addition of matter. There is nothing outside pure being that could act, with respect to it, as a differentiating feature, as the specific difference rationality is outside the genus animal or as matter is outside form, because ‘outside’ pure being there is only non-being, and non-being is nothing. So pure being could not be differentiated, as pure being, into multiple instances of itself, such as pure being A, pure being B, pure being C, and so on. Hence, a purely actual reality that was pure being itself – and such is the classical theist's picture of God – would have to be unique, out of metaphysical necessity.

This is a classical argument from the impossibility of multiplication that can be (and has been) stated in multiple ways. Other versions, for instance, draw the same conclusion out of additional attributes that are derived from the nature of a purely actual thing, such as its absolute simplicity. If a purely actual thing has to be absolutely simple or non-composite (and plausibly it has to, given that any composite is in potency with respect to its parts, or is a mixture of act and potency), then for there to be two absolutely simple beings, A and B, A would have to exhibit feature X that B lacked, in order for them to be differentiated. But then A would not be an absolutely simple being, because it would have parts, contrary to the hypothesis – A would be what B is plus feature X. So, once more, there could not be any feature that distinguished two hypothetical absolutely simple things, without making it the case that one of them or both were not, after all, absolutely simple.Footnote ¹¹

Thus, in principle, there can be no more than one absolutely simple being or one purely actual thing.Footnote ¹² Pure-act theism, then, both gives us the simplest possible answer to the question of how many First Causes there are and provides us with an explanation of why there has to be that number instead of any other – namely, because there could in principle be no more than one purely actual thing, so it is a necessary feature of a purely actual thing that it be unique.

But now, to compare, let's take Graham Oppy's proposal that there is a first necessary initial state of physical reality, from which every other non-initial state follows by indeterministic causation (Oppy (Reference Oppy2013a), 12–13 and (Reference Oppy and Goldschmidt2013b), 134).Footnote ¹³ And let's ask ourselves the same question: how many things or items make up such a first necessary initial state? Presumably, any number we were to give would have to be necessary, because, since we are talking about a necessary initial state, it could not have been otherwise than it is. So the number of items that make it up must be necessary. The problem, however, is twofold. First, there does not seem to be any way to even guess how many items make up such a first initial state, so that any number we were to pick (47, 55, 10⁸⁰, but also even 1) would seem entirely arbitrary. But second, there does not seem to be a way either of explaining why any given number of initial items would have to be necessary. Why would such a number be necessarily 1 or 47 instead of 55 or 10⁸⁰? What about the nature of initial physical items would make it impossible for there to be one more or one less than a given number N? We can, of course, say that, whatever number is the correct one, it will have to be necessary, but we can't say which number it is nor why.

Indeed, Oppy (or the naturalist in general) could simply plead ignorance about the number of initial items and leave its determination to future physics.Footnote ¹⁴ However, I think this would be problematic mainly for three reasons. First, the appeal to currently unknown future science cuts both ways. For all we know, maybe future physics will teach that the First Cause is a purely actual reality and that this is the best way to give an ultimate explanation of the existence of everything else. We may not want to call such a future science physics, but something like physics* (more akin to metaphysics or philosophy of nature), but when dealing with future science we can't anticipate what paradigm shifts we will undergo or how radical they may be.

Second, it is not at all clear that physics per se (or future physics, in case it remains physics as we understand it) can determine whether a given past physical state is truly initial (that is, first), or not. I think the current clash between those scientific models that take the Big Bang to be the beginning of all physical reality and those that take it to be merely the beginning of our spatio-temporal region illustrates this point. It seems, then, that whether a given past physical state of the universe is the First Initial State or not will have to remain an open question for future physics just as much as for current physics. This may be an indication that the question about the First Cause's nature is of the purview of metaphysics, not physics – it is the question about what could there possibly be at the origin of reality.

But third, even if future physics could determine the number of initial items, it is even harder to see how it could explain why there had to be, necessarily, that many initial items, not one more, not one less. I can at least picture, extrapolating from current scientific practice, how a future physics could determine the number of initial items, granting it could determine that a given state was truly initial. But there doesn't seem to be anything in current physics that would allow us to expect that future physics (again, qua physics) will be able to explain why a number N of initial physical items could not have been possibly different. So the appeal to future physics would seem to boil down, in the end, to an expression of naturalistic faith.

On the contrary, as we've already seen, if we say that the first initial state is a purely actual reality, we can immediately know how many First Causes there are and why, with the additional virtue that we get the simplest possible answer (namely, one). I take it that, for anyone who finds the evidence in favour of causal finitism to be compelling, this may become a tempting reason to adopt a theory of the First Cause (or the initial state) as purely actual.Footnote ¹⁵

The argument without causal finitism

In the previous section, I have framed the argument in the context of causal finitism because I consider it to be a very promising and plausible hypothesis, capable of gathering over time a growing consensus among professional philosophers. So the fact that pure-act theism may have this advantage as a theory of the First Cause could become a strong enough reason to bring it back to the fore of contemporary philosophical debate, thus accepting Pruss's invitation to a joint inquiry into the nature of causal finitism's implied ultimate cause (Pruss (Reference Pruss2018b), 17). But the same point could be made in a more traditional way, to someone who did not grant causal finitism. Historically, the main arguments for classical theism have not tried to establish God as a First Cause in the distant-past causal history of things (that is, as the first member of a linear or per accidens causal series), but as that First Cause which here and now sustains everything else in existence, providing the ultimate explanation of their present and continued being (that is, as the first member of a hierarchical or per se causal series).Footnote ¹⁶

If one were to accept, maybe through an appeal to the PSR or other arguments, that there has to be some necessary foundational layer of reality whose being, so to speak, ‘held’ the ordinary objects of our experience in existence,Footnote ¹⁷ then we could speak of such reality as a First Cause and the same questions as before would arise: How many entities make up this First Cause, this foundational reality, and why? And here, again, pure-act theism would be able to answer both questions, whereas Oppy's parallel alternative account could not.

Let's take, for instance, a proposal inspired by some remarks of Graham Oppy in his 2019 debate with Edward Feser.Footnote ¹⁸ Responding to Feser's Neo-Platonic proof, which argues that composite objects could not exist here and now unless an absolutely simple and purely actual cause was continuously sustaining their existence (Feser (Reference Feser2017), 69–86), Oppy seemed to want to block the inference to an absolutely simple and divine cause by positing, in the foundational necessary layer of reality, a multiplicity of ‘metaphysical simples’, which in turn were supposed to make the same explanatory work as Feser's absolutely simple and purely actual God.

Now, leaving aside whether Oppy's undercutting objection succeeds (and the classical theist would not grant that it does, for metaphysical reasons), the point I want to make now is that the classical theist could, for the sake of argument, bracket the question of whether the existence of a purely actual cause follows of necessity from his premises and go on to argue, in an abductive fashion, that his is a better candidate of a First Cause than Oppy's. And this because, again, there does not seem to be a way to answer the question of how many ‘metaphysical simples’ make up the foundational layer of reality, and any number one may posit will seem arbitrary in the absence of an explanation of why there have to be that many, no more and no less. What would it be about the nature of 47, 55, 10⁸⁰ ‘metaphysical simples’ (or even 1!) that would make it the case that such an elusive number was actually necessary? What is it about the nature of ‘metaphysical simples’ that would make it impossible for there to be more or less than a given number N of them? No answer seems to be forthcoming.

On the other hand, by adopting the pure-act theist's hypothesis – namely, that at the foundational layer what we have is a purely actual reality – the same advantage as before obtains: we get to know how many items make up such a necessary foundation and why. So, if both (purportedly) do the same explanatory work, the pure-act theist's candidate has the advantage of shedding some additional light and intelligibility into such a foundational reality. Classical theism, then, appears both simpler and more fruitful than Oppy's naturalism, since it can answer more questions about the First Cause with fewer principles (namely, with just one purely actual thing). This is a significant advantage vis-à-vis Oppy, who tends to favour the weighing of theories according to their theoretical virtues (Oppy (Reference Oppy2013a)).

At this point, a naturalist who accepted that the classical theist has here a non-negligible theoretical advantage might wonder whether he could not just adopt the idea of a purely actual first cause without committing himself altogether to theism. He would grant, then, that both at the first initial state of reality and at its core foundational layer there is a purely actual natural entity, in regard to which everything else would be dependent for its ultimate metaphysical explanation. Instead of a pure-act theism, we would have a kind of pure-act naturalism, the difference being that the naturalist would not call such a being ‘God’, nor consider it to be worthy of any kind of religious reverence. To this I would say that, in the absence of any alternative account of the First Cause that met the classical theist's advantage or any considerations that counterbalanced it, extending his view into a kind of pure-act or pure-being naturalism seems to be the reasonable move for the naturalist, constituting a sign of philosophical progress. However, the question of whether such an account would not be, after all, theism under a different name could be raised, especially if further inquiry into the nature and attributes of such a purely actual first reality was to continue.

After all, the pure-act theist would argue that several traditional divine attributes can be deduced from the nature of the First Cause as purely actual. It would be interesting, then, to see how many of the divine attributes such a hypothetical pure-act naturalist could consistently admit into his or her understanding of the First Cause. Both immutability and immateriality, for example, seem unavoidable and straightforward once the pure actuality of the First Cause is embraced, since change is essentially the passage from potency to act and every material thing is both mutable and potential in many ways. Would the naturalist feel comfortable adding to his ontology a purely actual, immutable, and immaterial First Cause of things? It's hard to say. Maybe he could, granted that he resisted strongly the derivation of the more personal attributes, such as intellect and will.

In any case, these considerations would take us beyond the purposes of this article and much more into the so-called ‘Gap Problem’. However, given the powerful arguments both for a First Cause and for a Necessary Foundation, I take it that the Gap Problem is the next frontier in the theism–naturalism debate. If the argument in this article is correct, it could constitute a first step in that direction, making pure actuality an attractive foundational feature of the First Cause to consider.

The argument without pure-act theism?

Now, I do not want to propose that this is some kind of decisive or knock-down argument or reason to definitively prefer pure-act theism over all rival alternative accounts of the First Cause, even non-classical theistic ones. I do want to say that, all things being equal, and given the fact that Oppy gives the most fleshed out naturalistic account of the First Cause, this advantage may be sufficient to incline the balance of theoretical virtues in favour of classical theism over naturalism. But, of course, all things are not always equal. Multiple considerations could be brought to bear in order to counterbalance this purported advantage.

For instance, it is hardly ingenious to notice that classical or pure-act theism has become a pretty controversial brand of theism in contemporary philosophical debate, especially in the analytic tradition. Hence, someone who found problematic such derived attributes of a purely actual reality as immutability or simplicity could have here a very strong reason to resist my argument. Such a person could justifiably think that the classical theist's advantage is not worth the price of having to accept such a counterintuitive first entity. More to the point, a Christian theist who thought that there was a severe incompatibility between absolute divine simplicity and the doctrine of the Trinity would probably consider the ascribed advantage as minimal, if not monstrously outweighed by its disadvantages.Footnote ¹⁹

So, what I want to explore now is how the argument in this article could be adapted to fit theism in general, and not only classical or pure-act theism. Two avenues seem to me clearly available: one that focuses on God's omnipotence and another that focuses on God's unlimited or perfect nature. As we'll see below, I think it is the last one that appears most promising.

To start with the first, almost all branches of theism will ascribe omnipotence or maximal power to God. But there are several arguments to the effect that there could only be one omnipotent being. Joshua Hoffman and Gary Rosenkrantz, for instance, ask us to imagine that there could be two omnipotent beings, Dick and Jane, both existing at the same time in the same possible world:

With an argument like this, the non-classical theist could claim the same advantage we have been arguing over in this article – namely, that by adopting the hypothesis that the First Cause is God, who possesses omnipotence as one of his essential attributes, we get to know how many First Causes there are (one) and why (because, necessarily, there can only be one omnipotent being). The worry here would be that the cost, for the naturalist, of adopting this attribute in order to meet the challenge seems to be significantly lower than before. It is hard to see how one could ‘re-construct’, so to speak, the traditional picture of God just from the attribute of omnipotenceFootnote ²⁰ and without having to appeal to metaphysical principles that would, in the end, commit us to classical or pure-act theism, which the non-classical theist wants to avoid.Footnote ²¹ So it seems that the naturalist could just stop at some kind of omnipotent-being naturalism and leave it there.

Hence, it may be better to try to frame the argument in light of God's unlimited or perfect nature.Footnote ²² Again, nearly all branches of theism understand God to be an absolutely or maximally perfect being. But it seems plausible that there can only be one absolutely or maximally perfect being, because for there to be two of them, they would need to be distinguished either by a perfection that one of them had and the other lacked or by having the same perfections to differing degrees. But in each case, either one of them or both would not be an absolutely or maximally perfect being, contrary to hypothesis. So, once more, by adopting a theistic theory of the First Cause as absolutely perfect, we could get to know how many First Causes there are (one) and why (namely, because there can only be one absolutely perfect being).Footnote ²³ Now it is not as clear as before that the naturalist can meet the challenge in the same way, for adopting some kind of perfect-being naturalism would bring him too close to theism, which he wants to avoid. And though viewing the First Cause as purely actual may provide some metaphysical grounding for its absolute perfection, a perfect-being understanding of God seems at least prima facie defensible without either having to collapse immediately into classical or pure-act theism or having to embrace its more controversial divine simplicity attribute.