What Is Divine Simplicity? (And Why It Matters)

An introduction to an ironically complicated idea about God.

I finally found a little time to put together another narration video for Philosophy for the People—this one introduces viewers to the notion of divine simplicity. Below is the video, followed by the full script (with references/embedded links to further resources).

Honestly, I wish I could promise to make these videos more regularly, but even the short ones take a ton of time—since I not only write the script myself, but also record the audio and then do all the (admittedly pretty rough) video editing. Still, I’ll do my best to make this a somewhat more regular thing. In the meantime, I hope you enjoy this one!

The doctrine of divine simplicity is the claim that God is absolutely ontologically simple—that is, God is not composed of any parts, whether physical or metaphysical.

“Part”—or more precisely, component part—should be understood broadly here to mean any item (feature, entity, principle, etc.) that is ontologically prior to a whole and, in some sense, less than that whole, yet contributes to the whole’s being. In other words, a component is something more metaphysically basic than the whole it helps constitute.

As peculiar as the doctrine of divine simplicity might sound to contemporary ears, it was in fact the dominant conception of God throughout much of the history of the philosophy of God—affirmed by thinkers across many religious and philosophical traditions, including Christian (Augustine and Aquinas), Jewish (Maimonides), Muslim (Avicenna), and Pagan (Plotinus).

The reason divine simplicity was affirmed by such a wide variety of thinkers is that God, traditionally, was always understood as a theoretical entity serving a particular function—namely, a foundational one. God is where the ontological buck stops, so to speak: the ultimate reality in the order of being and the ultimate explanation in the order of discovery.¹

Simply put, God is the foundational source from which all contingent, finite, and mutable realities spring forth—the uncreated, underived, eternal, necessarily existing, and self-explanatory first principle of everything. And the reason so many thinkers, past and present, have understood God in this way is because they judged that such an entity must exist if there is to be a realm of contingent, finite, and mutable realities at all—realities that, of themselves, are not fully self-explanatory either as to why they exist or why they have the characteristics they do.²

If one grants the plausibility of this general picture, divine simplicity follows rather swiftly—in fact, one could argue it is simply the logical result of a few straightforward conceptual truths. For example:

1. A composite, by definition, depends on ontologically prior components.

2. Whatever depends on something ontologically prior is not ultimate.

3. God, by definition, is ultimate.
   ∴ Therefore, God is not composite.³

This argument has long struck many thinkers as both swift and decisive. In some ways, it seems as obvious as a parallel argument that virtually no theist rejects:

1. A caused entity, by definition, depends on a cause.

2. Whatever depends on something is not ultimate.

3. God, by definition, is ultimate.
   ∴ Therefore, God is not a caused entity.

Of course, neither argument is meant as a proof for the existence of God. Rather, both are intended to clarify how God should be understood in light of prior commitments—specifically, commitments about fundamentality. To reiterate: A composite is, by definition, whatever results from the conjunction of its various components: an entity whose being, character, or both depend upon the unification of distinct parts. But no such entity could ever be truly ontologically basic or fundamental.

By contrast, God is precisely that which is supposed to be metaphysically ultimate—uncaused, underived, and absolutely fundamental. One notion implies dependence; the other, independence. The two are strictly incompatible. Thus, if one is going to affirm the existence of God as traditionally understood, one should—and indeed must—affirm God as absolutely simple.

Of course, much more could be said about the basic motivation behind divine simplicity—including how it is best understood within the context of a wider constituent ontology—but hopefully that’s enough to impress the general point.

Before saying goodbye, I should mention the obvious: not every theist accepts divine simplicity, and for various reasons. Some believe the notion of an absolutely simple God is incompatible with how God is portrayed in Scripture. Some of the tensions arise not directly from simplicity itself but from what it seems to entail—for example, eternality, immutability, and impassibility. Others reject divine simplicity because they worry it leads to unwelcome philosophical consequences, such as modal collapse. (For instance: if this world is produced by God, but God is simple and could not have changed, then how could God have done otherwise? Doesn’t it seem, on that view, that this world had to exist—not as contingent after all, but as necessary?)

These are technical debates, and they extend far beyond the scope of this video. Still, I will close with two challenges. The challenge for the classical theist—especially if they are Christian—is to articulate an account of divine action that preserves real contingency in, and responsiveness to, creation, while still maintaining simplicity. For what it’s worth, many contemporary classical theists—including the narrator of this piece—have attempted to meet this challenge by proposing various extrinsic models of divine action (and knowing), which seem to allow for the preservation of simplicity in God alongside genuine contingency in creation and responsiveness to creatures.⁴

The challenge for the non-classical theist who rejects divine simplicity, by contrast, is to provide a model of God that allows for mutability, possibility, and so forth, without ultimately rendering God a composite—and thus a derivative—entity. After all, as the old adage has it, for something to change, some thing must remain the same. This is why the very notion of mutability has long led metaphysicians to conclude that changeable beings are, in some real ontological sense, composite—that they have various components which make sense of how real change can occur.

If you’d like to me discuss each of these challenges in more detail in a future video, please let me know. Until then, thank you for watching.

1. See Edward Feser, “What Is Classical Theism,” in Classical Theism: New Essays on the Metaphysics of God, ed. Jonathan Fuqua & Robert C. Koons (Routledge, 2023).

2. Insert whatever broad cosmological argument you like here. My book has one; here’s another.

3. This argument (or a very close variant) is not only endorsed by Aquinas and many classical theists before him, but has also been defended by contemporary classical theists. For example, see James E. Dolezal, God Without Parts (Pickwick Publications, 2011).

4. See, for example, W. Matthews Grant, Free Will and God’s Universal Causality (Bloomsbury Academic, 2019), and