Divine Simplicity: A Shopper's Guide to Ultimate Reality

So, you’re considering different models of God and are curious about classical theism, which is committed to the controversial (and, let’s admit it, kinda spooky) doctrine of divine simplicity (DDS from here on out). This doctrine asserts that whatever is in God is God—alternatively, that there are no real distinctions within God that would amount to ontological composition. In other words, God is utterly simple and incomposite.

Perhaps I can help. I, too, was once in your shoes, considering various models of God, having formerly been an atheist. Eventually, I concluded that if God exists at all, divine simplicity must be true. That was my intuition many years ago, and it remains my intuition even now. Of course, it’s more than intuition—I think there are compelling arguments for it.

So, here’s the plan for today: I’d like to outline—briefly and in a survey-like manner—some reasons for accepting divine simplicity. But since the doctrine has its fair share of detractors (oh boy, does it ever), I’ll also highlight responses to the more prominent objections. Naturally, I can’t explore every argument or defense in detail here; each topic would require, at minimum, a hefty volume. My modest goal is to help curious readers move in the right direction—or at least give them something more to think about. I aim to provide resources to understand what motivates the doctrine and to show why objections, often seen as formidable, may not be so after all.

Speaking of objections, here’s probably the worst reason to reject divine simplicity: because it’s a “Catholic” thing. Honestly, I’ve seen people make this association, and while it’s true that Catholicism dogmatically commits its members to affirm God as absolutely simple, it 1) doesn’t necessarily commit them to the Thomistic understanding specifically (though I think that’s the correct one), and 2) divine simplicity is far from being just a Catholic doctrine.

It’s also a pagan thing, a Hindu thing, a Jewish thing, an Islamic thing—and, very importantly, a classical and traditional Protestant thing. While I won’t be defending DDS strictly from within the Protestant tradition, there are many Protestants—like James Dolezal and Gavin Ortlund (both of whom I’ve discussed divine simplicity with; here and here)—who do exactly that.

So, even if you have some weird thing against Catholics (watch it, buddy!), that’s really not a good reason to reject DDS!

Divine Simplicity: The Basic Motivation

The most basic motivation behind divine simplicity is that it seems to be the only way to secure the ultimate intelligibility of reality—that is, to avoid positing brute facts. The general idea goes something like this: there are things that exist but could have failed to exist; we call these things contingent. And we typically think there should be an explanation for why any contingent things exist at all. To avoid an explanatory circle, this requires positing something necessary—something that cannot not exist.

Again, that’s the basic thrust of general cosmological reasoning (for more detailed development see my book), and many people, including atheists who accept the existence of a necessary reality, feel its force. The problem is, by itself, this reasoning doesn’t tell us much—not about God, nor even whether this necessary reality is God. That’s why atheists can, and sometimes do, accept the initial stage of cosmological reasoning.

To fill the picture in a bit, we should look to the classical tradition, where many philosophers understood contingency as closely related to compositeness—particularly metaphysical compositeness. A prime example is Aquinas’s constituent ontology of essence and existence. According to Aquinas, everyday contingent objects—cats, trees, humans, and so on—are comprised of two fundamental principles: essence (their what-ness element) and existence (their is-ness element). These principles, while inseparable as long as the object exists, are really distinct. The essence of any contingent thing does not “guarantee” its existence.

But compositeness, even aside from Aquinas’s ontology, obviously raises its own set of questions, doesn’t it? After all, we naturally want to know why the parts of a thing not only exist but also have the particular arrangement that they do—especially when there’s nothing about the nature of the parts themselves that demands their unity, togetherness, or specific configuration.

In many cases, it’s clear that the unity of the parts is funded by an extrinsic cause, and the whole is entirely dependent on the existence and arrangement of those parts. Think of artifacts or aggregates, like a table, a chair, or a lawnmower. But not all cases are that straightforward. Sometimes, with certain physical parts—say, the cells of a cat—it might seem that the parts are somehow whole-dependent, deriving their nature (and function) from being part of the whole.

This might suggest that wholes are entirely prior to their parts, and thus there is no requirement to look for some further cause or explanation, but that’s not quite right. Even this position—where at least some parts seem dependent on the whole (in certain respects, though not in all)—for it to be coherent and not radically unintelligible, requires adopting a broadly Aristotelian paradigm, which commits us to metaphysical parts—particularly parts like form or essence For instance, the cat’s cells derive their nature because of the cat’s form. But then we can ask: how did the cat’s form come to be united with the cat’s matter? After all, this union is not necessitated by the nature of the form itself, since other cats share the same form (e.g., "cat-ness," though numerically distinct in each individual). Moreover, the form can be lost—such as when the cat dies—causing the cat to cease to exist as its matter undergoes substantial change. Anyway, Here’s the key point: we cannot appeal to the whole composite as the explanation because the hylomorphic compound (form + matter) is obviously metaphysically downstream—that is to say, posterior (in terms of explanatory significance)—to its metaphysical parts. After all, the composite has its nature because of its form and its particularity because of its matter. In fact, it is nothing over and above the unity of these metaphysical parts—where, by contrast, a hylomorphic composite is importantly something more than just the sum of its physical parts precisely because it includes metaphysical parts.

The reason I bring all this up is to show that even in the trickiest cases of compositeness—where the whole might seem, in some sense, prior to certain physical parts—we are ultimately driven back to other parts, specifically metaphysical ones, that are undeniably (in some significant sense) prior to the whole and find themselves in a relation of mutual simultaneous dependency. Thus these metaphysical parts still require further explanation for their unity or togetherness—an explanation that cannot come from the parts themselves or the whole without falling into circularity.¹

Thus, just as in other, more straightforward cases, we are compelled to look for a cause—something that ultimately grounds and funds the unity of these constituents.

Anyway, once you have that general idea in mind, it should become clear why so many philosophers thought that if we’re going to get to an ultimate, adequate explanation of things—particularly composite things—we must escape the category of compositeness altogether and arrive at something absolutely, ontologically simple—or, as Plotinus called it, The One.

If we connect these intuitions about compositeness to Aquinas’s constituent ontology of essence and existence, we get something—I think—really neat. First, we can begin to understand certain objects as contingent precisely because there is nothing about their nature that demands their inclusion in reality. But we can also begin to think about ultimate reality as the incomposite being whose essence just is its existence.

The upshot of this, I think, is enormous because it allows us to provide a truly principled foundation for reality. In other words, the nice thing about simplicity is that these questions concerning composition or contingency don’t arise once you get to God. Why? Because you don’t have to ask how the parts of something with no parts came together, and you don’t have to ask why something whose essence just is its existence exists—for its nature just is to be. (In fact, divine simplicity explains God’s necessary existence in virtue of God’s essence just being His existence. The classical theist, in other words, is actually entitled to say that Existence Exists—and it is God.²)

One might, of course, question the ultimate coherence of these notions (for what I believe is a decisive defense of the coherence of this paradigm of existence, see Barry Miller’s The Fullness of Being), but one cannot deny that they provide a principled stopping point with respect to the ultimate foundation of things and the ultimate intelligibility of reality.

The point I would like to press—because it was so firmly pressed upon me—is that what we ultimately want for ultimate reality is a relevant difference: what could be relevantly different about fundamental reality such that it not only does not have or need a cause but could not, in principle, possibly have a cause?

Just saying that fundamental reality is necessary, or has fewer parts, or is first in a line of things, or is bigger, or smaller, or way more powerful—none of these, not a single one, seems at all relevant to providing a principled basis for true ontological independence. However, something being utterly simple, whose essence is its existence, I think, so obviously does provide this principled basis. It is clearly relevantly different and is just the sort of thing—spooky as it initially seems—that could end our explanatory hunt.

So, there you have it—the (again, very general) motivation for divine simplicity. The simple point is that many of the truly greatest minds in philosophical history seemed to think it was simplicity or bust. If reality is to be completely intelligible, then we must trace back or “twist up” to The One—the single ultimate source of actuality (pure actuality itself) from which a system of finite composite natures finds their being and form.³

One final, brief point on this matter: As Lloyd Gerson argues—defending the view that all of “Big Tent Platonism” (encompassing thinkers like Plato, Aristotle, and Plotinus) is necessarily committed to divine simplicity—this commitment ultimately secures the very conditions necessary for philosophy itself, as it provides the foundation for a worldview capable of avoiding skepticism, reductionism, relativism, and so on. In other words, the guiding principle here is that the network of all hetero-explicable phenomena (things requiring extrinsic explanation or causes, things which are restrictedly intelligible) must ultimately trace back to some auto-explicable phenomenon (that which is completely, intrinsically intelligible, or self-explanatory). Furthermore, this auto-explicable phenomenon must be fundamentally distinct from the hetero-explicable realm, which is characterized by mutability, materiality, contingency, and—ultimately—metaphysical compositeness. This leads us to posit, as the necessary theoretical foundation, a reality that is immutable, necessary, and incomposite—or, in a word, absolutely simple. In another word: God.

Other Reasons to Accept Simplicity

Aside from what I think is the strongest reason to accept simplicity—namely, to secure the ultimate intelligibility of reality (a conclusion drawn from the best forms of cosmological reasoning)—there are many additional reasons or, if I may, benefits. I don’t expect all of these “upshots” to appeal to everyone. Some will resonate more (or only) with theists, while others might appeal to those who already accept—or want to accept—certain philosophical positions.

Of course, many of these arguments—like many of the cosmological arguments for divine simplicity—are “system-dependent,” meaning they require the assumptions or commitments of a particular metaphysical or philosophical program, such as essence realism. Some see this as a problem; I don’t. For the precise reason that Big Tent Platonism (or Perennial Philosophy) seems to me the best philosophical picture on the market—the one that makes the most sense of the most things, entirely apart from considerations of God’s existence. If this system not only leads to the existence of Simple Being (God) but also provides the theoretical commitments that allow one to engage in a robust philosophy of God, then to me, those are all features and benefits—far from bugs!

That being said, let me briefly outline what I believe these reasons are. (Admittedly, I’ll be making big claims that I can’t substantiate in this post, but I’ll provide references to where I believe they are strongly supported.)

1. Some Good Company!
   As Ed Feser puts it, when it comes to understanding the nature of God, “Classical theism is the approach to doing so that has dominated Western philosophy and theology for most of their history. Its roots are in scripture and Greek philosophy, especially the Neo-Platonic and Aristotelian traditions.”⁴
   Indeed, philosophers who affirmed some form of divine simplicity—or something close to it—read like a who’s who of philosophy and include: Plato, Aristotle, Plotinus, Proclus, Augustine, Boethius, Anselm, Thomas Aquinas, Duns Scotus, Avicenna (Ibn Sina), Averroes, and Maimonides. There are plenty of others, of course, and while arguments from authorities are far from the most persuasive or powerful, they certainly count for something.

2. Other Arguments.
   Cosmological reasoning isn’t the only thing that points toward divine simplicity—of course not. For a great example of how one might affirm divine simplicity through complementary philosophical approaches, I recommend Alexander Pruss’s essay, Some Arguments for Divine Simplicity. In it, he presents a powerful cumulative case for simplicity, offering arguments from creation and parthood, perfection, pantheism and transcendence, attribute-instance simplicity, the New Testament claim that God “is” (not merely “has”) Love, and more.

3. Securing God’s “Unique Uniqueness” (Monotheism in Principle).
   Divine simplicity establishes the radical uniqueness of God by precluding the possibility of multiple gods—an attractive feature for theists who want a principled basis for robust monotheism, rather than it just being a happy accident that there’s only one God. There are several (I think, compelling) arguments from simplicity to God being “uniquely unique.”
   
   The short story of one such line of thought, at least within Aquinas’s constituent ontology, is that the multiplication of entities necessarily involves composition—a feature that is impossible for God, who is ontologically simple. Put differently, for Aquinas, if something’s essence is identical to its existence, that something must be simple and self-subsistent. However, having multiple instances of such an entity would contradict its nature as simple (or self-subsistent, or both). Why? Because multiplicity would require features of commonality and difference (even trivially so, whether or not discernible to us) that must be ontologically grounded, thereby introducing composition—directly contradicting simplicity.⁵
   
   For a defense of this argument, see Peter Weigel’s excellent volume Aquinas on Simplicity. https://amzn.to/3B2lh7O.

4. Securing God’s Transcendence.
   Divine simplicity ensures that God is entirely unlike anything in the created order. God is not a finite being (one with arbitrary limits⁶) or a contingent being, but fundamentally other—transcendent in the truest sense, with a clear divide between the created and uncreated order. Metaphysical composition is the dividing line (even immaterial beings, like angels, are still metaphysical composites in Aquinas’s system), and it’s what ultimately allows for a being—one and only one—to be absolutely, rather than just relatively, perfect.

   
   In other words, DDS entails that God isn’t just another being among beings (even one far more powerful or knowledgeable—higher on the scale, so to speak). Instead, God is unrestricted Being itself, entirely off the scale—a point we’ll revisit presently when we discuss God as the limit-case instance of various attributes.

5. Avoiding Euthyphro.
   Divine simplicity rather easily resolves the infamous Euthyphro dilemma by identifying God with the Good itself. To understand how this works, it’s crucial to recognize that classical theism isn’t just about divine simplicity—simplicity emerges from a much more robust metaphysical program, which includes many other commitments, including about the nature of goodness.
   
   As it happens, one of these commitments—controversial but defensible—is that goodness and being are convertible (the same in reference, though different in sense). With this in place, the upshot is that the classical theist can neatly slide between the horns of the otherwise thorny Euthyphro dilemma: “Does God will something because it is good, or is something good because God wills it?”
   
   The answer: God wills what is good because God is The Good as such. And indeed, things are good (possess goodness) because God wills them, supplying them with being.
   
   In other words, classical theism is embedded within—or rather emerges from—a metaphysical system where axiology (the study of value) and ontology (the study of being) converge at the ultimate reality: God. Like everything else, God acts according to His nature. But as pure actuality or pure subsistent existence, God just is pure subsistent goodness itself—again, The Good itself.
   
   (Of course, I’m hardly the first to suggest this advantage of classical theism. In fact, in her magisterial volume Aquinas, Eleonore Stump argues that divine simplicity offers uniquely powerful resources for addressing two notoriously difficult issues in philosophical theology: the avoidance of brute facts and the resolution of the Euthyphro dilemma.)

6. Securing Libertarian Freedom.
   As Matthews Grant has masterfully argued, divine simplicity entails an extrinsic model of God’s agency. The short story here—and let me emphasize, I cannot recommend Grant’s book highly enough—is that for something to be determined, there must be a factor that is both prior to and logically sufficient for whatever that something is. However, these conditions simply don’t apply under the extrinsic model of divine agency that follows from classical theism. Why? Because God causing us—or any of our acts—just consists in that act coming about qua dependent upon God. In other words, while God’s producing our act is logically sufficient for it, it is not prior to it. (And had our act or choice been different, it would simply have been the case that what God caused would have been different.)
   
   On this model—about which much more can be said (again, see Grant’s book)—determinism is avoided, allowing one to affirm two positions that might otherwise seem initially at odds: libertarian human freedom and God’s universal causality. By contrast, it’s very unclear—perhaps even impossible—to see how a non-classical or complex-theist avoids determinism, especially if when they posit some factor (e.g., God forming an intention) that is both prior to and logically sufficient for an effect. Indeed, this is often exactly what they do, thinking it helps resolve modal collapse issues.
   
   But as I’ll explain below, not only is this addition unnecessary, it doesn’t even solve the problem they think it does—at least, not on its own. In fact, their approach, if it works at all, ends up relying on the exact same sort of move the classical theist makes—just with more (totally unnecessary) complication! Christopher Tomascevski highlights this point with the question he poses to Ryan Mullins and Bill Craig (both major critics of DDS) here.

7. Stabilizing Constituent Ontology.
   In my forthcoming paper, The Millerian Cosmological Argument, I argue that certain constituent ontologies would not only result in brute facts if composite entities were uncaused but would actually involve contradictory structures—rendering such entities impossible. While I won’t spell out the argument here, if I’m correct, then simplicity is required to stabilize constituent ontology. This is crucial because constituent (as opposed to relational) ontology seems to me the obviously correct way to go!

8. Resources for Meta-Epistemology (Avoiding Skepticism).
   Many have argued that the principle of sufficient reason (PSR) is necessary to avoid catastrophic skepticism. If the general thrust of the cosmological reasoning above is correct, the only way to satisfy PSR—and thus avoid brute facts—is to accept divine simplicity. Moreover, as I’ve discussed with Gaven Kerr, I believe simplicity also provides resources for answering the question, “How does God know He isn’t a brain in a vat?”—a question that, in my view, complex-theists cannot adequately answer. And that, I think, is a significant issue—especially if one wants to affirm that God is perfect!

9. The Problem of Evil.
   While I believe successful theodicies (yes, more than one) can be given by classical theists (see my book for what I argue is the best), divine simplicity offers the rather unique resource of dismissing the problem of evil as rooted in a confusion of categories. Specifically, it denies that God is a moral agent like we are moral agents—without, at the same time, denying that God is perfectly good. This is the approach taken by thinkers like Fr. Brian Davies, which I won’t fully defend here but will simply gesture toward as worth exploring. (For a great example of this response deployed against a recent formulation of the logical problem of evil, see Edward Feser’s essay responding to James Sterba.)

10. Avoiding Trinitarian Heresy.
    Ironically, while simplicity is often alleged to rule out Trinitarianism, a more substantial metaphysical investigation suggests that simplicity is actually necessary to secure orthodox Trinitarianism insofar as it helps avoid endorsing either modalism or tritheism. For this subject, I highly commend the work of Bernard Lonergan and (for a more condensed account) James Dolezal.

Again—there you have it! Just a few reasons I think everyone should take the doctrine of divine simplicity seriously, whether they ultimately accept it or not. Of course, every story has two sides. Just as there are many arguments offered in favor of divine simplicity, there are plenty of arguments pressed against it as well. Let’s now turn the discussion to consider what might be said in defense of divine simplicity against these various critiques.

In General Defense of Simplicity: a Principled Mysterianism.

Let me begin this section by offering a general point of defense for the doctrine of divine simplicity. Speaking personally, I find the motivations for DDS to be clear and, frankly, dispositive. (I get that others might see things differently, but that’s just how I see it!) On the other hand, the objections to DDS seem far less compelling—certainly not dispositive. When we prioritize what is clear over what is not, I think we find strong, if not entirely decisive, reasons to embrace simplicity.

Now, while I believe there actually are solid answers to the most challenging objections to DDS—some of which I’ll highlight in a moment—what I really want to emphasize is this: even if there weren’t solid answers to every objection, I still wouldn’t be too worried. Why? Because I think proponents of DDS can legitimately appeal to mysterianism.

I call it principled mysterianism because appeals to mystery don't seem legitimate when there’s a reasonable expectation of understanding the answer or explanation. (Let’s call those instances, creatively, unprincipled mysterianism.) For example, I find mysterianism regarding consciousness for physicalists unprincipled—it feels like a copout, especially since there’s no really solid reason (assuming physicalism is true) to think consciousness shouldn’t eventually yield to the same combinatorial-quantitative analysis that explains everything else.

However, there are cases where we have good reasons to believe that:

1. There definitely (or probably) is an answer or explanation, but

2. We definitely (or probably) won’t be able to fully “see” or understand that answer or explanation.

Both points, I think, apply to God and DDS. Through cosmological reasoning, we have strong grounds to believe that DDS provides the foundation for ultimate intelligibility. At the same time, because God is radically transcendent and entirely other, our grasp of the divine nature is—unsurprisingly—extremely limited and incredibly thin. (In other words, we can know that there must be a necessary foundation for certain kinds of things—and that it must have or lack certain features—while also knowing that the nature of such a foundation largely eludes us.)

Moreover, the doctrine of analogy (more on this in a moment) reminds us that God’s mode of power, knowledge, and relation to the world is considerably different from ours. Therefore, in response to various challenges, it’s entirely reasonable to say something like:

“I don’t know exactly how God, as pure actuality, can know contingent realities without undergoing intrinsic change. But:

1. I know this follows as a consequence of the theory, and

2. Because God’s mode of knowing (and relation to the world) is obviously very different from ours, I have no reason to think this is impossible or incoherent.

So… yeah, it seems perfectly reasonable to affirm DDS, even if I don’t see exactly how it works.”

Divine simplicity (DDS), in other words, anticipates mystery. It is neither cheap nor an easy cop-out for the classical theist to make a mysterian appeal when addressing objections to the doctrine—whether it’s issues of modal collapse, the coherence of divine attributes, God’s causality, or human libertarian freedom.

In other words, the classical theist can reasonably say:

1. I have strong reasons to embrace DDS.

2. Those same reasons give me good grounds to believe that, at the level of God, things are radically different, profoundly strange, and far beyond what I can fully comprehend.

3. Because of this, I have reasonable grounds for not abandoning DDS in the face of objections that fail to fully appreciate the transcendence (or “other-ness”) of God and God’s mode of being—whether in knowing, causing, or otherwise.

Final point before moving on: Divine simplicity has been around for a long time and has been hotly debated for just as long. It’s easy for anyone to spend a little time digging up a laundry list of technical objections in the literature and presenting them shotgun-style (or just endlessly putting new spins on perennial issues, which is also common). But seriously—and here I’m looking at all you young, impressionable men on YouTube or social media who frequently email me in various states of confused panic when encountering such things—it’s time to stop falling for these philosophical scare tactics. Laundry lists like these can be compiled against pretty much any position.

And to my fellow Christians, let me say this: if you’re intimidated by long lists of seemingly formidable objections, the bigger challenge isn’t DDS—it’s something we call The Trinity. (Ironically, as I suggested above, I think embracing simplicity is one of the best ways to make the doctrine of the Trinity coherent—or at least defend it against charges of incoherence.) My point is this: if you’re so quick to abandon a position just because it’s mired in controversy, you might want to check yourself. Not only is this attitude—as I’ve explained before—unproductive; it’s often downright irrational.

For now, stop being timid or wimpy. Objections exist—many of them seemingly powerful—against all positions (at least any of popular significance). Don’t flee with your tail between your legs. Face them head-on. Stage a proper investigation. Almost always, there’s goodness, truth, and clarity to be found in working through objections. And if that feels like too heavy a task, then you might seriously need to ask yourself whether philosophy is really for you.

Two Objections Briefly Considered

With all that being said—and to reiterate an earlier point—I do believe there are good responses to the toughest objections against DDS. To be sure, many of these responses involve positing models that are possibly true for all we know. But in most cases, that’s more than sufficient to defuse the complaint.

Quite often, these responses ultimately provoke—that is, at the end of the argumentative rainbow—the familiar “OK, but that’s really weird/super implausible” reaction from committed critics. To this, the classical theist can rightly say two things:

1. Plausibility is often in the eye of the beholder. Terms like “plausible,” “highly plausible,” or “super-duper implausible” are—let’s face it—very philosophical terms that sound precise but don’t always carry much weight, especially when we’re deep in end-stage philosophical investigation.

2. Weird, in this context, is actually OK. After all, we’re talking about fundamental reality—why on earth should we expect what we discover there to be familiar? In fact, it would be weird (in a bad sense) if what we said about God did feel totally familiar, just like everything else we encounter. If anything raises a red flag, it’s that.

So, I’m not at all bothered by the “this is super weird/highly implausible” response, and I don’t think anybody else should be either. This kind of reaction, like much of what happens in philosophy, is person-relative—contingent upon their prior beliefs, the wider web of ideas they hold, and the communities and culture they find themselves in, among other things.

Modal Collapse Objections

There is a family of objections related to various forms of modal collapse that seem to be the most pressing of all criticisms against DDS. Modal collapse refers to the ultimate erasure of the contingent/necessary distinction, particularly within the created order. In the most general sense, the problem is this: how does one get contingency from necessity? That is, how is it that necessity itself doesn’t necessitate everything—which, if true, would mean that all that appears contingent really isn’t (hence, the collapse).

Much of the time, these objections—when specifically formulated against DDS rather than just a necessary being—are not directly aimed at simplicity itself but at a logical consequence of simplicity: God’s immutability. In short, the critic is asking how a God who is simple and immutable can cause, will, know, or love a mutable, contingent reality without Himself undergoing change. The problem, in short, is this: Either God must change when performing such acts (which contradicts both immutability and simplicity), or God must perform such acts by nature (thus resulting in modal collapse).

I believe the best way to handle these objections is to adopt an extrinsic model of divine action (including willing and knowing) with respect to creation, where all the contingency, as it were, is “located” extrinsic to God. Ultimately, this approach allows one to say that God remains intrinsically invariant across possible worlds, and that God’s causing, willing, or knowing this world is nothing other than this world coming into existence with a real causal dependence on God.

There’s a lot to consider in these accounts, and different responses are needed depending on how the objection is formulated. However, I believe most, if not all, of these challenges can be addressed by following the lines I’ve outlined above. (Of course, it’s worth noting that many classical theists propose entirely different solutions—that is, by not adopting an extrinsic model—which they believe are ultimately more effective; I’m simply offering one particular approach that satisfies me).

Nevertheless, it’s important to emphasize that, at least within Aquinas’s metaphysics, nothing about the extrinsic model is contrived or ad hoc; in fact, it seems to follow naturally from scholastic commitments already in place. For example, God’s creative action is direct and immediate, and, as classical Aristotelianism (recently defended by David Oderberg) holds, the action of the agent is “in the patient.” In other words, God’s act of creation does not involve any “turning, twisting, or mutating” within God Himself but is simply creation coming about as causally dependent upon God.

Some argue that this makes creation entirely random, but this objection is mistaken—it’s really just a variant of the classic randomness objection to free will (the false dilemma of “if not determined, then random”). There is a third category: reasons-based action, the kind of action we routinely engage in when making free and rational choices.

By way of a very brief (and admittedly inadequate) summary: for scholastics, the will is understood as the active power to end deliberation and settle on a set of reasons as efficacious for action—reasons that are not inherently determinative (only the Good itself is inherently determinative). While this understanding must be modified when applied to God—since He doesn’t "mull things over" or deliberate step-by-step across time—there’s no reason to think an analogically similar account cannot apply here.

Moreover, because God acts based on reasons, His creation of this world is clearly intentional. The classical theist simply holds that God’s intending this world is nothing more than this world coming into existence as causally dependent upon God.

Spooky? ...Maybe? Weird? I don't know—is it? It’s definitely not unprecedented. Anscombe held a similar view of intentional action, and other philosophers, entirely apart from theological concerns, already hold that human knowing consists in relations between the knower and the known object, making such cognitive states extrinsic to the cognizer. So, there is certainly nothing the classical theist needs to feel "embarrassed" about when endorsing these positions to safeguard simplicity. These conclusions are not unreasonable (they follow naturally from a well-motivated theory) and definitely not incoherent—especially when the classical theist already has good reason to think the ontology of God’s action is quite unlike ours.

(Again, there are many very technical presentations of modal collapse-style arguments and equally technical responses. I don’t wish to diminish their rigor or ignore the immense detail involved in these debates—my purpose here is simply to point in what I believe is the generally correct direction.)

Simplicity and the (Alleged) Diversity of Divine Attributes

Another prominent objection to divine simplicity (DDS) concerns the claim that whatever we attribute to God is really identical to God. This leads to the conclusion that all divine attributes—power, knowledge, goodness, love, etc.—are not only identical to the divine essence but also to each other. At first glance, this seems odd—indeed, as philosophers like to say, rather implausible.

For my money, there are two key points to address in response to this objection:

1. Examining (and Rejecting) Certain Assumptions

First, it’s important to examine the assumptions behind the objection. For instance, are critics thinking of attributes as abstract properties, thereby importing a kind of Platonism about predications that proponents of DDS would strongly reject? For the Platonic (“extreme”) realist, these properties are distinct, independently existing entities in their own right. Not only that, but identifying God with them would bizarrely seem to reduce God to an abstract property Himself—a critique famously raised by Alvin Plantinga.

If—if, if, if!—one is a Platonic realist in this respect, the traditional account of divine simplicity might indeed seem obviously nonsensical—because it would be! (Though ironically, if a Platonist adopts relational ontology, things end up metaphysically simple anyway, committing them to a kind of divine simplicity. But that’s a topic for another time.)

The necessary response here is to point out that classical theists reject all such assumptions, particularly the idea that such predications are ontologically committing in the way someone like Plantinga thinks they are. More specifically, they deny that properties or attributes should be understood as independently existing entities in some Platonic third realm or as something to which we bear a relation of exemplification. (Additionally, classical theists would seriously qualify the use of the term "property," drawing important distinctions between real and Cambridge properties, as well as between accidental and essential properties. This distinction is significant because, while classical theists maintain that God cannot change with respect to His real intrinsic properties, they allow for legitimate contingent attributions to God insofar as they refer to mere Cambridge or relational changes—such as God becoming the creator of the world. These attributions do not require positing any real intrinsic change in God.

Thus, if anyone claims that classical theists assert God cannot have any contingent properties, they are mistaken. The correct position is that one can never make a contingent attribution to God that implies any intrinsic passive potency.)

Finally, I should mention that there are several positive contemporary accounts defending DDS against objections like this one, and that I think do an exceptionally fine job. For example, Jeffrey Brower and others have developed and defended a truth-maker account of divine simplicity. I find this account both attractive and plausible (maybe even "especially plausible"—OK, I’ll stop ;)—and Brower’s paper is definitely worth reading, particularly for the exceptionally helpful clarifications about what simplicity is and isn’t committed to.

In short, Brower suggests that we think of the divine substance or essence as the truthmaker for intrinsic predications about God. Ultimately, this means that when we say things like "God is powerful" or "God is good," these statements can be interpreted as meaning that God Himself (not some abstract property distinct from God) is the truthmaker for such predications.

So, yeah, check that out if you want.

2. The Principle of Analogy and Limit Cases

Second, we must reemphasize the principle of analogy—what might be called the use of “stretch concepts” when attributing positive qualities to God— and draw a critical distinction, following Barry Miller, between a limit simpliciter and a limit case. Ultimately, these point to the same idea: God possesses something like power and something like knowledge as we commonly understand them. However, in God, these “something like” instances are not distinct but are one and the same ontological entity, identical with the divine essence itself.

As Ed Feser explains:

“…when we predicate knowledge or power to God, we are for most classical theists not using the terms ‘knowledge’ and ‘power’ in the same sense as when we predicate knowledge or power to human beings or other created things. Rather, we are saying that there is in God something analogous to what we call knowledge in us and something analogous to what we call power in us. Hence, though what we call ‘knowledge’ and ‘power’ in us are certainly distinct, it doesn’t follow that what we call ‘knowledge’ and ‘power’ in God must be distinct, because the latter are not exactly the same as the former, even if they are related.”⁷

To approach this from Barry Miller’s perspective: a limit case is the point toward which an ordered series converges, but which is not itself a member of that series. For example, a circle is the limit toward which a series of polygons with an increasing number of sides converges. There is a real similarity between the circle and the polygons, but also a radical distinctiveness.

And right there, we have the basis for analogy—because there must be some similarity that the limit case bears to the ordered series. Otherwise, we could just swap in any random item or entity as the limit case for any series (which is obviously false). A circle is clearly the limit case of an ordered series of polygons, whereas a standstill is clearly the limit case of an ordered series of decreasing speeds—not the other way around. Yet, while the limit case bears this similarity, it is also something obviously very different or distinct from the series it concludes.⁸

Anyway, analogical predication is, once again, critical because it allows us to conceive of God as the limit-case instance of various attributes, which in turn resolves the difficulties associated with the idea that "all that is in God is God."

The reason this works is fairly simple (and essentially restates what Feser already explained and what Thomists have always strongly emphasized): while it may seem challenging (to say the least) to understand how power and knowledge, in the forms familiar to us, could be identical, there’s no reason to think that the limit-case instance of power couldn’t be identical to the limit-case instance of knowledge, etc.⁹

Conclusion

There are many more words—mountains more—that could be shared both in favor of and against the doctrine of divine simplicity. But here, I at least hope to have shown, minimally, that this doctrine is far from some outmoded, crusted-over piece of medieval philosophy. Instead, it has long served as the controlling principle of philosophical theism among many of the greatest minds in human history.

Appreciating this fact is what leads many classical theists—like David Bentley Hart (somewhat antagonistically, I admit)¹⁰—to claim that denying divine simplicity is essentially embracing atheism. The ultimate point of such a statement tracks closely with Lloyd Gerson’s work, particularly his project of Big Tent Platonism. Gerson argues that this tradition is effectively about making philosophy, as a distinct subject matter, possible by rejecting skepticism, nominalism, relativism, mechanism, reductionism, and so on—and providing the necessary theoretical resources to do so. It accomplishes this by affirming a rather holistic philosophical system, replete with finality and form, ultimately punctuated by that which is entirely auto-explicable—a reality that is completely self-explanatory. In other words, the absolutely simple first principle of everything.

Rejection of such a principle—even by other theists—ultimately renders ultimate reality categorically no different from what atheists might posit: a reality incapable of explaining everything that ought to be explained, saddled with brute facts, and unable to make reality hang together as a coherent whole. This is a theism I would reject outright if it were my only alternative to atheism. In that respect, I remain an atheist concerning all forms of theism outside the classical tradition.

Further Resources

You might want to begin with

William F. Vallicella

‘s excellent Stanford Encyclopedia Article on Divine Simplicity. I would also commend his book A Paradigm Theory of Existence.

As necessary scaffolding for DDS, I highly endorse Barry Miller’s book The Fullness of Being for a defense of the coherence of the notion of subsistent existence. His book specifically defending DDS, titled A Most Unlikely God, is still easily one of the best on the market (though, unfortunately, almost impossible to find; check your library loan system) and one that many of the major critics seem to consistently overlook or ignore.

Edward Feser does a fine job introducing DDS in his book Five Proofs and swatting down common objections. David Bently Hart engages a similar project in The Experience of God.

Eleonore Stump defends DDS in various places—start with Aquinas, but then quickly read her God of the Philosopher and God of the Bible (here, she’s specifically interested in how a simple, immutable God can personally relate to and love His creatures).

Matthews Grant motivates and defends DDS in his book Free Will and God’s Universal Causality. He also has other published work rebutting various modal collapse-type objections.

Michael Dodds' book The Unchanging God of Love is also excellent.

John Haldane offers an impressive philosophical case for (and defense of) DDS in his debate book with Jack Smart.

Pruss defends DDS against three objections in his article On Three Problems of Divine Simplicity.

There are several very worthy articles either arguing for or defending DDS in Classical Theism: New Essays on the Metaphysics of God (Pruss makes a cumulative case; Christopher Tomascevski defends against modal collapse; Dolezal defends God’s impassibility).

Aquinas on Simplicity by Weigel is fantastic, and so is Aquinas’s Way to God by Kerr.

Of course, my book The Best Argument for God also motivates and defends DDS.

There are many more, and I’m sure I’m forgetting lots of good ones since this is just off the top of my head, so check back later for updates.

In the meantime, I have many conversations about divine simplicity on my YouTube channel. To start, you might enjoy this replay of an interview John DeRosa conducted with Christopher Tomaszewski on DDS.

1. Caleb Cohoe explains that—for the Aristotelian—while wholes may be prior to some their parts in some respects, this does not make composite entities ontologically independent. Minimally, the whole still depends on its parts for matter and thus cannot exist without them. For a full argument on why a truly self-sufficient being must be simple, see Caleb M. Cohoe, "Why the One Cannot Have Parts: Plotinus on Divine Simplicity, Ontological Independence, and Perfect Being Theology," The Philosophical Quarterly 67, no. 269 (2017): 751–771.

2. But what about our existence—what exactly is that? I’ve suggested in various places that we should think of our existence as something like *our being caused to exist* or bearing a certain (causal) relation to Existence itself. This understanding allows us to retain the theoretically fruitful constituent ontology of Aquinas without unnecessarily bloating our ontology or reifying acts of existence (which individuate and actualize concrete entities) as individual things in themselves.

Understood this way, while there are individuated acts of existence, there are no individual acts of existence. The upshot of this is that it avoids certain regress objections—like whether acts of existence themselves require further acts of existence—and so on.

3. Some might suggest that the notion of perfection could do the theoretical work here (instead of simplicity), but there are several problems with this, as I’ve explained before. First, it’s unclear that positing a perfect being avoids a commitment to simplicity. In fact, many philosophers—like Anselm—argued the opposite: that perfection entails simplicity. For Anselm, perfection requires absolute completeness, which can only be the case if the being is simple and indivisible. A perfect being cannot have parts or distinctions that contribute to its being, as this would imply it is not fully actualized and would lack essential perfection. Now, if we're talking about plausibility, that certainly seems incredibly plausible to me! But I'll rest content with the modest point for now that perfection doesn’t clearly avoid simplicity; in fact, (almost certainly, if you give any weight to intuitions about great-making properties) it commits you to it. (For what it’s worth, Alexander Pruss also presents an argument from perfection to simplicity in his essay Some Arguments for Divine Simplicity, linked above).

Moreover, as I argued in the linked post, perfection by itself doesn’t—because it can’t—do the theoretical work required here. What's needed, if we're to have any clear understanding of what perfection is or amounts to, is a proper metaphysic. And the best account of perfection, I suggest—that is, one that properly grounds and explains what perfection actually entails—is one where God’s perfection arises from and is explained by God’s essence being identical to His existence.

To summarize: If we affirm that God is absolutely simple and purely actual, we have a coherent account of His perfection. That is, we can explain why it makes sense to say God is perfect and what that actually means. How so? According to the traditional view, perfection is the actualization of a species-specific potential (traditionally, perfection meant being “thoroughly made”). Things are perfected to the extent that they fully become what they are meant to be, according to their essence. God, being purely actual and whose essence is identical to His existence, is necessarily perfect—He has no potentials left to actualize and no further perfection to attain.

Furthermore, because God is unrestricted act, or simply existence itself, He does not possess a limiting essence. Therefore, His perfection is unlimited or absolute, rather than relative to any particular kind. This, I believe, is a much stronger account of perfection, emerging naturally from a prior metaphysic (which itself results in the existence of God) rather than from speculative (and, to my mind, highly dubious) a priori intuitions about what properties may or may not be great-making. However, it also entails that perfection emerges from—and is explained by—God's simplicity and His essence just being His existence (rather than the other way around), which further explains God’s ontological independence. It's a very tidy system!

4. Feser, Edward. "What Is Classical Theism?" In Classical Theism: New Essays on the Metaphysics of God.

5. Here’s another argument: Because God just is His existence, He exists necessarily. If there were several such beings, then each would also have to exist necessarily—that is, be truly ontologically independent by virtue of some common feature, namely, their one nature, which just is their existence. However, any feature by which one might supposedly differ from the other cannot belong to an a se being whose essence just is its existence. Why?

Because any additional feature must be either contingent or necessary (essential):

1. If the feature is contingent, then the being is composite—no longer simple—and causable, which directly contradicts the notion of a simple, uncaused being.

2. If the feature is necessary (essential), then each being would lack some essential feature that the other possesses. But if one being lacks an essential feature, it cannot be truly necessary (essential).

In either case, trying to suppose there could be more than one a se being whose essence is identical to its existence leads to a contradiction.

6. The notion of having an explanation of all arbitrary limits is emphasized by Joshua Rasmussen in the contemporary literature on cosmological reasoning and tracks closely with the traditional insight of any being with a finite (restricted) essence requiring an outside cause.

7. Five Proofs, 191-192.

8. As it happens, Miller contends that there are two irreducible accounts of real similarity: one, where certain things share a common feature or property; and two, between ordered series and their limit-case instances (if there be one).

9. In fact, classical theists like Miller argue that ordered series of properties that are plausibly purely positive in themselves (i.e., they don’t inherently imply a limit—like power, knowledge, goodness, love, etc.) all converge in a single limit-case instance as a certain distinguishing property (namely, one that implies potentiality or limit, like passivity with respect to knowledge) is varied to the point of extinction (resulting in knowledge that is somehow entirely active or executive).

Honestly, what an incredible thing to think about—it strikes me as profoundly true. I’m giving that one a super-duper-duper plausible ranking!

10. In his characteristically infuriating—or endearing, depending on who's reading—style, Hart refers to non-classical theism as "mono-poly-theism."