I have little to say directly in response to Ryan Mullins’s superb Conversation starter. Instead, I develop two lines of thought. First, I pile on Ryan’s critique of divine simplicity by pressing the question of my title, What sorts of parts is God supposed to be without? Second, having cleared some ground, I point to examples of what I consider fruitful – that is, a biblical – uses of divine simplicity. As will become clear, a biblically-grounded Trinitarian ontology animates both lines of argument.

Parts

We may stipulate: God has no physical parts. The question has to do with other kinds of “parts” – metaphysical or temporal. In his classic treatment of simplicity (Summa theologiae, I.3), Thomas Aquinas deals mainly with metaphysical parts. Anything with metaphysical parts is composite. Negatively stated, simplicity is a denial that God is a composite of form and matter, essence and existence, substance and accident, genus and species, potency and act.

Thomas considers simplicity to be crucial for a proper philosophical theology. According to Peter Weigel’s account,[i] simplicity underwrites other attributes and is a necessary postulate to make sense of biblical claims about God. Only a simple God can be eternal, omnipresent, and immutable. Only a simple God transcends the fragmentary composites of the created world. Only a simple God, Thomas insists, can create. Every composite must be composed by something. If God were composed, He would be held together by something other than Himself. He couldn’t be the first cause because He would Himself be caused. Simple/composite thus corresponds to Creator/creature.

One line of response might be: Thomas’s assumption that composites must be composed by another is drawn from observation of created composites. Is the argument haunted by an implicit univocity, which assumes that “composite” must have an identical meaning for Creator and creatures? Why project features of created compositeness onto an eternal, uncreated composite (if such exists)? Perhaps the Creator-creature boundary isn’t marked by the distinction, simple v. composite, but by the distinction, self-composed v. other-composed. We can’t conceive a being whose parts and wholeness are equiprimordial and mutually constituting, but then we can’t conceive of a simple being either. An ineffably composite God seems to protect the Creator-creature distinction just as well as an ineffably simple one. I assert nothing here. I merely ask, Why not?

More fundamentally, we need to probe the notion of a “metaphysical part.” Even if we believe these exist, how we describe and assess them depends on the metaphysical framework we’re using. Thomas doesn’t call God a substance because substances are form-matter composites. If I don’t think substances are form-matter combinations, I don’t think of form and matter as parts of substances. And I can say God is a substance, and still, if I like, affirm divine simplicity. Mereology – the theory of parts – is a dimension of a larger metaphysical vision.

To illustrate further: As it developed in the fourth century, Trinitarian ontology modified classical mereology. According to Eunomius the Arian’s reasoning, anything bearing an “in-relation” must be an accident, in-hering in and therefore dependent on the substance in which it exists. To say “X is in Y” is to assert X is an accidental part of Y. Arianism follows smoothly from this traditional mereology. Gregory of Nyssa answers from John 1: The Father is the arche; the Word is “in the arche” and yet the Word is Himself God, Life, and Light. In fact, Gregory adds, Eunomius’s reasoning turns the Father into an accident of the Son, since the Father is “in” the Son just as the Son is “in” the Father (John 14:10-11). A mysterious mutual in-ness is the very life of God. Within Trinitarian ontology, what was traditionally considered an “accident,” and therefore a part, isn’t.[ii] Mereology, to repeat, is a dimension of a metaphysics.

Mental or Real Distinctions?

So, Thomas’s claim about God’s lack of metaphysical parts is relative to his larger metaphysical scheme. Given that scheme, does he make a convincing case for viewing these metaphysical parts as parts? What is the basis for thinking that “act” and “potency” are “parts” of anything? Or “essence” and “existence”? After all, we never encounter an essence that doesn’t exist, nor an existing thing that isn’t a what. We may, if we like, mentally disassemble things into parts, and then example the parts as if they were components. To moderns, that seems a bald reification. The distinctions appear to be purely conceptual, and conceptual clutter at that.

Thomas, following Aristotle, insists these distinctions are distinctions in reality and not merely according to reason (secundum rationem tantum). What’s the argument?

Aristotle’s argument for an extra-mental form/matter distinction is an argument from change. Wood burns into ash. If wood is simply destroyed and replaced by ash, there is no change. Change happens to something, and so there must be a something that persists through the change from wood to ash. Aristotle, and Thomas too, don’t think atoms are the subjects of change. The form can’t be the persistent subject either, since the form is clearly altered: Ash is a different thing from wood. What persists through the change is prime matter. As Thomas puts it, “matter is the first subject standing under not only motions, which are with respect to quality and quantity and other accidents, but also with mutations which are respect to substance” (Commentary on Aristotle’s Metaphysics, VII 1.2).[iii] Matter and form must be distinct parts of a substance, else we couldn’t account for change.

We now know that Aristotle and Thomas were wrong about atoms (so were ancient atomists, for that matter), a considerable weakness in the argument. Besides, it’s not clear the argument hits the target. Matter doesn’t exist except as informed; pure matter is pure potency, and things must be actualized to be actual. But how is pure matter that isn’t “in act” without the addition of form different from a concept of pure matter? For that matter, what’s the difference between this matter without qualities or quantity or any other category, and nothing at all? Pure matter seems nothing but a limit concept needed to support a theory of change.

One of Thomas’s signal contributions to philosophical theology is the claim that God is distinct from creatures in that His existence (esse) is His essence (essentia). Knowing what a creature is (essence) doesn’t entail that it is (existence). In God, however, essence and existence are identical.

For Thomas, esse isn’t simply the bare fact that a thing really is. Something has esse if it “exists in nature,” whether it exists as a substance, accident, or in some other mode. In its most basic sense, esse signifies the form, and refers to the entire concrete object. Esse can also refer to the truth of a proposition. Blindness isn’t a substance or accident, but a privation. It doesn’t have esse in the first sense. But the proposition “blindness is” is true of someone who is blind. In its richest metaphysical sense, esse names a thing’s actuality or “act of existence.”[iv]

Thomas believes the distinction of esse, understood in this sense, and essentia is more than a distinction of reason, but it’s not clear that his arguments do the job.[v] Thomas writes,

every essence or quiddity can be understood without something being understood about its existence, for one can understand the essence (quid est) of a man or phoenix and nevertheless be ignorant about whether it has being in reality. Therefore, it is obvious that being is other than essence or quiddity, [that is] unless there is something the quiddity of which is its own being. Therefore, it is clear that being is other than essence or quiddity, unless there is something the quiddity of which is its own being (De ente et essentia c.4).[vi]

As Weigel observes, the argument moves “from a distinction in acts of cognition, how essence and existence can be objects of distinct acts of awareness, to a recognition that existence and essence are ontologically separate components of real things.” That is, “entertaining a concept of something, apart from considering the question of its existence, is sufficient evidence for an objective composition of essence and existence. This presumes that a mental division of labour is a reliable indicator of ontology.”[vii] Weigel summarizes other readings of the passage, but doesn’t think any of them bridge the gap from cognition to ontology. This leaves one of Thomas’s key sets of metaphysical parts dangling in the air.

I don’t need to settle the debate to return to my earlier point: esse and essentia are metaphysical parts only within a particular metaphysics. If “existence” isn’t something that can be possessed but refers to the sheer fact that something is, it seems inherent in what a thing is. We don’t know what a unicorn is unless we know that it’s mythical; mythicality is of the essence of unicornness. “Birds don’t exist,” the kids are saying these days, to which their elders wish to respond, “I don’t think the word ‘birds’ means what you think it means.”

To sum up: Thomas says metaphysical parts are extra-mental. Even if his arguments were persuasive, they’d be persuasive only within his metaphysical structure. To accept the mereology, one must accept the metaphysics. Many defenders of divine simplicity, Protestant and Catholic, are happy to bite this bullet. I think it’s a substantial obstacle. The second part of my argument is, even on Thomas’s own premises, his arguments are unpersuasive. What Thomas calls “parts” are, I submit, no more than distinctions of reason.

In The End of the Timeless God, Ryan complains about the effect of the simplicity axiom: Theologians sacrifice reams of pages and quarts of ink making fine distinctions in theology proper, only to reveal the distinctions don’t actually apply to God, since He’s utterly simple. I’m flipping his observation: Because the “parts” simplicity denies are no more than conceptual, the simplicity axiom isn’t a metaphysical postulate at all. This doesn’t make divine simplicity useless. It does leave it more modest. It’s a conceptual and linguistic constraint, a counsel of intellectual asceticism.

Simplicity and the Biblical God

If this is so, it sharpens and clarifies what’s at stake in the debate over simplicity: The status of biblical language about God. Simplicity can become an alternative language, displacing or even nullifying biblical revelation.

For instance: If God is simple in a strong sense, He’s a single, eternal act of existence. He doesn’t do one thing on today, and another thing tomorrow. He’s always and everywhere nothing but His eternal act of existence. You don’t have to read far into the Bible to run into problems with that. Within three verses, God has purportedly done a whole series of distinction actions: He creates, hovers over the waters, speaks, sees, separates, calls. It won’t do to say God is performing distinct acts within the frame of creation, but is in Himself a single undifferentiated act. If that’s true, the Bible isn’t showing God, but only showing God as He appears. And He’s actually quite different from the way He appears (though how would we know?). Revelation then does very little in the way of revealing.

It doesn’t need to be that way. The Cappadocians rejected a strong “identity” view of simplicity, which claims that God’s properties are identical to one another because all are identical to the essence of God. Instead, the Cappadocians affirmed the complexity of God’s properties and acts, and used simplicity as a caution that “one should not take these attributes as contradicting one another—since only complex beings can have contradictory properties at the same time.”[viii] To say simplicity is to confess the harmony, not the identity, of all that is in God.

On this understanding, simplicity isn’t a test of the revealed language of Scripture. The test applies in the opposite direction: Simplicity is legitimate insofar as it offers support to the revelation of the God of the Bible. It’s a useful theological concept insofar as it brings the biblical God into higher resolution, rather than making Him fuzzy. It’s a servant of, rather than master of, Scripture.

It’s possible to formulate Thomas’s esse-essentia axiom along these lines. Here I offer a compressed summary of Robert Jenson’s already pithy treatment.[ix] Aquinas teaches there’s a perfect coincidence of essence and existence in God: “What God is, if he is, itself guarantees that he in fact is.” What interests Jenson is the possibility that the convertibility of essence and existence works in the other direction: His essence is existence, but does “his existence sheerly as such constitute his essence? Is an otherwise unqualified act of existing the essence of God?” This unqualified act is the unified action of Father, Son, and Spirit. Jenson infers that “where the form divinity would be if ‘God’ were a word for a form, there is instead a triunely personal perichoresis, a communal life.”

Jenson accomplishes three quite dramatic things here. First, he shifts the question of esse/essentia away from the problem of metaphysical parts and composition into the realm of Trinitarian theology. Thomas arrived at his conclusion by the route of simplicity. Jenson picks the fruit and turns it in a fresh direction. Second, he shows there’s no generic category of “deity” of which the Triune deity is one instance; Triunity is a property a being must have to be God. Non-Triune gods are non-starters; they don’t even meet the minimum criteria to be considered divine. Finally, Jenson’s understanding doesn’t raise the specter of a God hidden behind the revealed God. Instead, he shows how metaphysical categories should be used: To force us to reckon with the God who acts in time, the Father who sends His Son and Spirit, the God of the gospel.

Peter Leithart is President of Theopolis Institute.


[i] Peter Weigel, Aquinas on Simplicity.

[ii] Giulio Maspero, “Life in Relation.”

[iii] Quoted in Weigel, Aquinas on Simplicity, 50-51.

[iv] Weigel, Aquinas on Simplicity, 68-69, expounding Thomas’s Commentary on the Sentences, II, d.34, q. 1. a.1.

[v] Weigel, Aquinas on Simplicity, 78-83.

[vi] Quoted in Weigel, Aquinas on Simplicity, 79.

[vii] Weigel, Aquinas on Simplicity, 81.

[viii] Andrew Radde-Gallwitz, Basil of Caesarea, Gregory of Nyssa, and the Transformation of Divine Simplicity, 6.

[ix] Jenson, Systematic Theology, I: The Triune God, 212-14.

Next Conversation

I have little to say directly in response to Ryan Mullins’s superb Conversation starter. Instead, I develop two lines of thought. First, I pile on Ryan’s critique of divine simplicity by pressing the question of my title, What sorts of parts is God supposed to be without? Second, having cleared some ground, I point to examples of what I consider fruitful – that is, a biblical – uses of divine simplicity. As will become clear, a biblically-grounded Trinitarian ontology animates both lines of argument.

Parts

We may stipulate: God has no physical parts. The question has to do with other kinds of “parts” – metaphysical or temporal. In his classic treatment of simplicity (Summa theologiae, I.3), Thomas Aquinas deals mainly with metaphysical parts. Anything with metaphysical parts is composite. Negatively stated, simplicity is a denial that God is a composite of form and matter, essence and existence, substance and accident, genus and species, potency and act.

Thomas considers simplicity to be crucial for a proper philosophical theology. According to Peter Weigel’s account,[i] simplicity underwrites other attributes and is a necessary postulate to make sense of biblical claims about God. Only a simple God can be eternal, omnipresent, and immutable. Only a simple God transcends the fragmentary composites of the created world. Only a simple God, Thomas insists, can create. Every composite must be composed by something. If God were composed, He would be held together by something other than Himself. He couldn’t be the first cause because He would Himself be caused. Simple/composite thus corresponds to Creator/creature.

One line of response might be: Thomas’s assumption that composites must be composed by another is drawn from observation of created composites. Is the argument haunted by an implicit univocity, which assumes that “composite” must have an identical meaning for Creator and creatures? Why project features of created compositeness onto an eternal, uncreated composite (if such exists)? Perhaps the Creator-creature boundary isn’t marked by the distinction, simple v. composite, but by the distinction, self-composed v. other-composed. We can’t conceive a being whose parts and wholeness are equiprimordial and mutually constituting, but then we can’t conceive of a simple being either. An ineffably composite God seems to protect the Creator-creature distinction just as well as an ineffably simple one. I assert nothing here. I merely ask, Why not?

More fundamentally, we need to probe the notion of a “metaphysical part.” Even if we believe these exist, how we describe and assess them depends on the metaphysical framework we’re using. Thomas doesn’t call God a substance because substances are form-matter composites. If I don’t think substances are form-matter combinations, I don’t think of form and matter as parts of substances. And I can say God is a substance, and still, if I like, affirm divine simplicity. Mereology – the theory of parts – is a dimension of a larger metaphysical vision.

To illustrate further: As it developed in the fourth century, Trinitarian ontology modified classical mereology. According to Eunomius the Arian’s reasoning, anything bearing an “in-relation” must be an accident, in-hering in and therefore dependent on the substance in which it exists. To say “X is in Y” is to assert X is an accidental part of Y. Arianism follows smoothly from this traditional mereology. Gregory of Nyssa answers from John 1: The Father is the arche; the Word is “in the arche” and yet the Word is Himself God, Life, and Light. In fact, Gregory adds, Eunomius’s reasoning turns the Father into an accident of the Son, since the Father is “in” the Son just as the Son is “in” the Father (John 14:10-11). A mysterious mutual in-ness is the very life of God. Within Trinitarian ontology, what was traditionally considered an “accident,” and therefore a part, isn’t.[ii] Mereology, to repeat, is a dimension of a metaphysics.

Mental or Real Distinctions?

So, Thomas’s claim about God’s lack of metaphysical parts is relative to his larger metaphysical scheme. Given that scheme, does he make a convincing case for viewing these metaphysical parts as parts? What is the basis for thinking that “act” and “potency” are “parts” of anything? Or “essence” and “existence”? After all, we never encounter an essence that doesn’t exist, nor an existing thing that isn’t a what. We may, if we like, mentally disassemble things into parts, and then example the parts as if they were components. To moderns, that seems a bald reification. The distinctions appear to be purely conceptual, and conceptual clutter at that.

Thomas, following Aristotle, insists these distinctions are distinctions in reality and not merely according to reason (secundum rationem tantum). What’s the argument?

Aristotle’s argument for an extra-mental form/matter distinction is an argument from change. Wood burns into ash. If wood is simply destroyed and replaced by ash, there is no change. Change happens to something, and so there must be a something that persists through the change from wood to ash. Aristotle, and Thomas too, don’t think atoms are the subjects of change. The form can’t be the persistent subject either, since the form is clearly altered: Ash is a different thing from wood. What persists through the change is prime matter. As Thomas puts it, “matter is the first subject standing under not only motions, which are with respect to quality and quantity and other accidents, but also with mutations which are respect to substance” (Commentary on Aristotle’s Metaphysics, VII 1.2).[iii] Matter and form must be distinct parts of a substance, else we couldn’t account for change.

We now know that Aristotle and Thomas were wrong about atoms (so were ancient atomists, for that matter), a considerable weakness in the argument. Besides, it’s not clear the argument hits the target. Matter doesn’t exist except as informed; pure matter is pure potency, and things must be actualized to be actual. But how is pure matter that isn’t “in act” without the addition of form different from a concept of pure matter? For that matter, what’s the difference between this matter without qualities or quantity or any other category, and nothing at all? Pure matter seems nothing but a limit concept needed to support a theory of change.

One of Thomas’s signal contributions to philosophical theology is the claim that God is distinct from creatures in that His existence (esse) is His essence (essentia). Knowing what a creature is (essence) doesn’t entail that it is (existence). In God, however, essence and existence are identical.

For Thomas, esse isn’t simply the bare fact that a thing really is. Something has esse if it “exists in nature,” whether it exists as a substance, accident, or in some other mode. In its most basic sense, esse signifies the form, and refers to the entire concrete object. Esse can also refer to the truth of a proposition. Blindness isn’t a substance or accident, but a privation. It doesn’t have esse in the first sense. But the proposition “blindness is” is true of someone who is blind. In its richest metaphysical sense, esse names a thing’s actuality or “act of existence.”[iv]

Thomas believes the distinction of esse, understood in this sense, and essentia is more than a distinction of reason, but it’s not clear that his arguments do the job.[v] Thomas writes,

every essence or quiddity can be understood without something being understood about its existence, for one can understand the essence (quid est) of a man or phoenix and nevertheless be ignorant about whether it has being in reality. Therefore, it is obvious that being is other than essence or quiddity, [that is] unless there is something the quiddity of which is its own being. Therefore, it is clear that being is other than essence or quiddity, unless there is something the quiddity of which is its own being (De ente et essentia c.4).[vi]

As Weigel observes, the argument moves “from a distinction in acts of cognition, how essence and existence can be objects of distinct acts of awareness, to a recognition that existence and essence are ontologically separate components of real things.” That is, “entertaining a concept of something, apart from considering the question of its existence, is sufficient evidence for an objective composition of essence and existence. This presumes that a mental division of labour is a reliable indicator of ontology.”[vii] Weigel summarizes other readings of the passage, but doesn’t think any of them bridge the gap from cognition to ontology. This leaves one of Thomas’s key sets of metaphysical parts dangling in the air.

I don’t need to settle the debate to return to my earlier point: esse and essentia are metaphysical parts only within a particular metaphysics. If “existence” isn’t something that can be possessed but refers to the sheer fact that something is, it seems inherent in what a thing is. We don’t know what a unicorn is unless we know that it’s mythical; mythicality is of the essence of unicornness. “Birds don’t exist,” the kids are saying these days, to which their elders wish to respond, “I don’t think the word ‘birds’ means what you think it means.”

To sum up: Thomas says metaphysical parts are extra-mental. Even if his arguments were persuasive, they’d be persuasive only within his metaphysical structure. To accept the mereology, one must accept the metaphysics. Many defenders of divine simplicity, Protestant and Catholic, are happy to bite this bullet. I think it’s a substantial obstacle. The second part of my argument is, even on Thomas’s own premises, his arguments are unpersuasive. What Thomas calls “parts” are, I submit, no more than distinctions of reason.

In The End of the Timeless God, Ryan complains about the effect of the simplicity axiom: Theologians sacrifice reams of pages and quarts of ink making fine distinctions in theology proper, only to reveal the distinctions don’t actually apply to God, since He’s utterly simple. I’m flipping his observation: Because the “parts” simplicity denies are no more than conceptual, the simplicity axiom isn’t a metaphysical postulate at all. This doesn’t make divine simplicity useless. It does leave it more modest. It’s a conceptual and linguistic constraint, a counsel of intellectual asceticism.

Simplicity and the Biblical God

If this is so, it sharpens and clarifies what’s at stake in the debate over simplicity: The status of biblical language about God. Simplicity can become an alternative language, displacing or even nullifying biblical revelation.

For instance: If God is simple in a strong sense, He’s a single, eternal act of existence. He doesn’t do one thing on today, and another thing tomorrow. He’s always and everywhere nothing but His eternal act of existence. You don’t have to read far into the Bible to run into problems with that. Within three verses, God has purportedly done a whole series of distinction actions: He creates, hovers over the waters, speaks, sees, separates, calls. It won’t do to say God is performing distinct acts within the frame of creation, but is in Himself a single undifferentiated act. If that’s true, the Bible isn’t showing God, but only showing God as He appears. And He’s actually quite different from the way He appears (though how would we know?). Revelation then does very little in the way of revealing.

It doesn’t need to be that way. The Cappadocians rejected a strong “identity” view of simplicity, which claims that God’s properties are identical to one another because all are identical to the essence of God. Instead, the Cappadocians affirmed the complexity of God’s properties and acts, and used simplicity as a caution that “one should not take these attributes as contradicting one another—since only complex beings can have contradictory properties at the same time.”[viii] To say simplicity is to confess the harmony, not the identity, of all that is in God.

On this understanding, simplicity isn’t a test of the revealed language of Scripture. The test applies in the opposite direction: Simplicity is legitimate insofar as it offers support to the revelation of the God of the Bible. It’s a useful theological concept insofar as it brings the biblical God into higher resolution, rather than making Him fuzzy. It’s a servant of, rather than master of, Scripture.

It’s possible to formulate Thomas’s esse-essentia axiom along these lines. Here I offer a compressed summary of Robert Jenson’s already pithy treatment.[ix] Aquinas teaches there’s a perfect coincidence of essence and existence in God: “What God is, if he is, itself guarantees that he in fact is.” What interests Jenson is the possibility that the convertibility of essence and existence works in the other direction: His essence is existence, but does “his existence sheerly as such constitute his essence? Is an otherwise unqualified act of existing the essence of God?” This unqualified act is the unified action of Father, Son, and Spirit. Jenson infers that “where the form divinity would be if ‘God’ were a word for a form, there is instead a triunely personal perichoresis, a communal life.”

Jenson accomplishes three quite dramatic things here. First, he shifts the question of esse/essentia away from the problem of metaphysical parts and composition into the realm of Trinitarian theology. Thomas arrived at his conclusion by the route of simplicity. Jenson picks the fruit and turns it in a fresh direction. Second, he shows there’s no generic category of “deity” of which the Triune deity is one instance; Triunity is a property a being must have to be God. Non-Triune gods are non-starters; they don’t even meet the minimum criteria to be considered divine. Finally, Jenson’s understanding doesn’t raise the specter of a God hidden behind the revealed God. Instead, he shows how metaphysical categories should be used: To force us to reckon with the God who acts in time, the Father who sends His Son and Spirit, the God of the gospel.

Peter Leithart is President of Theopolis Institute.


[i] Peter Weigel, Aquinas on Simplicity.

[ii] Giulio Maspero, “Life in Relation.”

[iii] Quoted in Weigel, Aquinas on Simplicity, 50-51.

[iv] Weigel, Aquinas on Simplicity, 68-69, expounding Thomas’s Commentary on the Sentences, II, d.34, q. 1. a.1.

[v] Weigel, Aquinas on Simplicity, 78-83.

[vi] Quoted in Weigel, Aquinas on Simplicity, 79.

[vii] Weigel, Aquinas on Simplicity, 81.

[viii] Andrew Radde-Gallwitz, Basil of Caesarea, Gregory of Nyssa, and the Transformation of Divine Simplicity, 6.

[ix] Jenson, Systematic Theology, I: The Triune God, 212-14.

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