I thank John Leslie and Robert Lawrence Kuhn for their gracious and substantive response to my recent comments on their fine anthology The Mystery of Existence: Why Is There Anything At All? In the course of my earlier remarks, I put forward a friendly criticism to the effect that John and Robert had paid insufficient attention in their book to the tradition of classical theism, which has its philosophical roots in Aristotelian and Neo-Platonic thought and whose many illustrious representatives include Augustine, Anselm, Avicenna, Maimonides, and Aquinas. Though there are selections from some of these writers, they are very brief, and the bulk of the theological selections in the book are from recent writers of what has sometimes been called a theistic personalist or neo-theist bent. John and Robert have offered a lively defense of their approach. In what follows Id like to respond, pressing the case for the primacy of the classical theistic tradition.

Classical theism, divine simplicity, and ultimate explanation

One of the points John and Robert make in their defense is an appeal to the very specific aim of their volume:

Our books limited mission is to build appreciation for the most baffling of all enigmas: Why is there something rather than nothing? In its shadow, all the big questions” Does God exist? Why the universe? Life after death? ”are eclipsed . . . .



In any event, The Mystery of Existence is not about the clash between classical and modern/personal forms of theism (theistic personalism), a distinction that is anyway not directly on point in explicating Nothing (our limited mission again), since in either case, classical or modern/personal, God can be in some sense necessary.

Now, while our editors are of course the best experts on their mission for the volume, I would respectfully disagree with them about the relevance of classical theism to that mission. For the philosophical dispute between classical and modern forms of theism is, I would argue, exactly on point. And when we understand why, we will also see that the question whether God exists is in no way eclipsed by the question why there is something rather than nothing”on the contrary, the existence of God, as classical theism understands God , is (so the classical theist would argue) the only possible answer in principle to that question. Let me explain.

Both classical theism on the one hand and theistic personalism or neo-theism on the other have their strictly theological aspects. There is, for instance, a longstanding dispute over which of these views better comports with what we find said about God in the Bible. I would certainly agree with John and Robert that such disputes are tangential to the aims of their volume.

However, both views also have a purely philosophical side, and their purely philosophical differences make a world of difference to the question of whether theism offers us any insight into the question of why anything exists at all. For you might say that classical theism in its philosophical aspect just is the development of the implications of there being an ultimate explanation of why anything exists at all. Theistic personalism or neo-theism, by contrast, is motivated by a different set of concerns, and touches on the question of ultimate explanation only in a secondary way.

At the core of classical theism is the notion of divine simplicity”the idea that God is non-composite or without parts. This is a doctrine having its philosophical roots in Plato and Aristotle and defended by pagan, Jewish, Christian, and Muslim thinkers as diverse as Philo of Alexandria, Irenaeus, Clement of Alexandria, Athanasius, Plotinus, Augustine, Boethius, Anselm, Maimonides, Avicenna, Averroes, Aquinas, and Scotus. The doctrine is the de fide teaching of the Catholic Church and is endorsed by many Protestant theologians. The point of all this name-dropping is to emphasize how absolutely central the doctrine of divine simplicity is to the mainstream Western tradition in philosophical theology. And why is it so central?

The reason is that for the classical theist, whatever else we mean by God, we certainly mean by that label to name the ultimate source, cause, or explanation of things. Properly to understand classical theism, the hostile atheist reader might even find it useful to put the word God out of his mind for the moment”given all the irrelevant associations the word might lead him to read into the present discussion”and just think instead of the ultimate source of things. The classical theist maintains that whatever is in any way composed of parts cannot be the ultimate source of things. For wherever we have a composite thing, a thing made up of parts, we have something that requires a cause of its own, a cause which accounts for how the parts get together.

This is obviously true of the ordinary things of our experience. For example, a given chair exists only because there is something (a carpenter or machine) that assembled the legs, seat, etc. into a chair. And the chair continues to exist only insofar as certain combining factors”such as the tackiness of glue or friction between screw threads”continue to operate. The point applies also to things whose composition is less crudely mechanical. A water molecule depends for its existence on the oxygen and hydrogen atoms that make it up together with the principles of covalent bonding.

But it is true at deeper metaphysical levels as well. Any changeable thing, the Aristotelian argues, must be composed of actuality and potentiality . For example, an ice cube melts because it has a potential to take on a liquid form that is actualized by the heat in the surrounding air. In any contingent thing, the Thomist argues, its essence is distinct from its existence . That is why a tree (say) can come into existence and go out of existence, since what it is to be a tree ”a trees essence or nature”by itself entails nothing one way or the other about whether it exists. Whether it is , you might say, is distinct from what it is . Actuality and potentiality, existence and essence are thus components of any thing that has both”even if they are metaphysical components rather than material components”and their composition entails that such a thing depends on a cause, on something that actualizes its potentials, that imparts existence to its essence.

So, whatever the ultimate source, cause, or explanation of things is”again, refrain from calling it God if you want”it cannot be made up of material components, or actuality and potentiality, or existence and essence. Nor can it be composed of any other metaphysical parts”genus and difference, substance and properties, or what have you. It cannot be an instance of a genus, for then it will require some aspect or other that differentiates it from other instances of that genus, and that entails having metaphysical parts. It cannot instantiate properties since that would, again, require some differentiating feature that sets it apart from other instances of those properties, which again entails having metaphysical parts.

Naturally, if it is the ultimate source, cause, or explanation of things it is actual or existent”it could hardly cause or explain anything otherwise”but it is not a compound of actuality and potentiality as other things are, nor a compound of existence and essence. It would have to be, always and already as it were, pure actuality rather than something that has or could have any potential in need of actualization. It would have to be, not an existent thing among other existent things, but pure being or existence itself. Anything less would require a cause or source of its own and thus not be the ultimate cause or source.

Note that on the classical theist view of ultimate explanation, there are no inexplicable brute facts. Things that require causes require them because they have potentials that need to be actualized and parts that need to be combined. To say of a thing that it has parts and yet lacks any cause which accounts for their combination, or has potentiality yet lacks any cause which actualized that potentiality, would be to make of it a brute fact. But that is precisely what the classical theist does not say about the ultimate cause of things. It says instead that, since it is purely actual (and thus devoid of potentials that could be actualized) and absolutely simple (and thus devoid of parts that could be combined), it not only need not have a cause but could not in principle have had one. It, and it alone, has its source of intelligibility in itself rather than in some external cause.

So, whatever else we say about the ultimate cause, source, or explanation of things”and whether or not we want to call it God, whether or not we want to identify it with the God of the Bible specifically, and whether or not we think it has any religious implications in the first place”we are going to have to regard it as absolutely simple or non-composite, as pure actuality devoid of potentiality, and as being itself rather than something that merely instantiates being. We are also going to have to regard it as immutable and uncaused, because only what has potentiality capable of being actualized, or parts capable of being combined, can be caused or undergo change, and the source or cause of all things must be devoid of potentiality or parts.

Now, whatever one thinks of this set of ideas”and obviously there are various questions and objections that might be raised”it is surely not eclipsed by the question of why something exists rather than nothing, and it is surely on point. For what the classical theist claims to be doing is elucidating what any possible answer to that question must involve. And as I have emphasized, this approach to that question is the dominant one in the history of Western thought. What could be more relevant to the mission of The Mystery of Existence ?

Theistic personalism versus classical theism

Theistic personalism or neo-theism”I borrow the labels from Brian Davies and Norman Geisler , respectively”is a very different story. This relatively recent movement in philosophy of religion and theology”represented by a diverse set of thinkers such as the analytic philosophers Alvin Plantinga and Richard Swinburne, process philosophers and theologians like Charles Hartshorne, and advocates of open theism like Clark Pinnock and William Hasker”is primarily motivated, not by questions of ultimate explanation, but by theological and philosophical objections to certain key aspects of the classical theistic conception of God. Indeed, theistic personalism is defined perhaps above all by its rejection of precisely that notion that the classical theist regards as essential to ultimate explanation”the idea of divine simplicity.

Whereas the classical theists philosophical analysis of the idea of God typically begins by thinking of Him as the ultimate cause of things, the theistic personalist begins instead by conceiving of God as a certain kind of person. Hence Alvin Plantinga characterizes theism as the thought that there is such a person as God: a personal agent who has created the world and is all-powerful, all-knowing, and perfectly good ( Where the Conflict Really Lies , p. ix). According to Richard Swinburne, that God is a person, yet one without a body, seems the most elementary claim of theism ( The Coherence of Theism , p. 99). One of the main objections theistic personalists often raise against the idea of divine simplicity is that it makes God out to be too abstract, and is irreconcilable with the idea that God is a person.

Now classical theists, in general, by no means regard God as im personal. They typically argue that when the notion of the ultimate cause of all things is fully developed, it can be seen that there is a sense in which we must attribute to this cause intellect and will . But the meaning of these terms as applied to God must be very carefully unpacked, and anthropomorphism avoided. And it is definitely a mistake from the classical theist point of view to start with the idea that God is, like us, an instance of the kind or genus person, who instantiates some of the same properties that other persons do, but has them to a higher degree and lacks some of the other properties (such as corporeality). Yet that seems to be the approach that the theistic personalist or neo-theist is at least implicitly committed to.

There are various objections that can be raised against this approach, but the most relevant one for present purposes is that insofar as theistic personalism implies that God has parts, or that he is one instance among others of a kind, or that like those others he instantiates properties, etc., it makes theism simply unsuitable as a candidate for ultimate explanation. For (as the classical theist sees things, anyway) it makes of God something essentially creaturely ”something which, like other composites, requires a cause of his own. Or if he doesnt have one, he will simply be a brute fact and thus not an ultimate explanation at all”something which, like other things, is composite, but which merely happens inexplicably nevertheless not to have been caused. This opens theism up to New Atheist-style objections to the effect that God is a metaphysical fifth wheel”something which at best seems dubiously preferable to taking the universe as the ultimate brute fact, and at worst seems ruled out by Ockhams razor.

The question of whether a deity of the theistic personalist sort exists or not therefore does seem eclipsed by the question of why anything exists at all, and not directly on point. And that was precisely my point in offering my friendly criticism of John and Roberts choice of selections for The Mystery of Existence . Given the books mission, it would, I argue, have been more appropriate to emphasize classical theist writers and give theistic personalist or neo-theist writers secondary consideration. But (as I have complained) the reverse course was followed.

An objection to divine simplicity

John and Robert offer a second defense of their choice of emphasis in the book by raising an objection to classical theism and its core notion of divine simplicity:

Classical theism really is puzzling . . . .



Aquinas sees Gods properties as all of them ultimately identical. Gods goodness just is Gods power, for example, and that just is Gods knowledge, which in turn just is Gods existence; for Gods essence simply is to exist . . . .



Aquinas may make some of this easier to accept through stressing that we speak of God only analogically. But doesnt that itself say that weve little idea of what were talking about, and that discussing it for many pages wouldnt alter this unalterable fact? Theistic readers of The Mystery of Existence may feel relieved when the personal theist Timothy OConnor tells them that while he, too, sees Gods goodness, power, and knowledge as intimately linked, he finds it very hard to be sure what Aquinas doctrine is supposed to come to.



Again, those readers may welcome Richard Swinburnes description of God as a spirit, a non-embodied person . . . To Richard, the claim that the divine properties are identical to each other and to God depends on the somewhat arbitrary way one divides up the properties of a thing (how many properties one says that some thing has) ” and that applies to all things, not only to God. And it remains extremely puzzling how a property can be the same as a substance in which it inheres.

The first thing to say in response is that it cannot be emphasized too greatly that divine simplicity is not merely Aquinas  doctrine. It is by no means the eccentric teaching of a single thinker or two. Rather, it is the common heritage of the entire mainstream Western tradition in theology and philosophy of religion, endorsed by the major pagan, Jewish, Christian, and Muslim thinkers referred to above and incorporated into the official theology of Roman Catholicism. The thinkers in question may disagree over certain details, but they all affirm that divine simplicity itself is non-negotiable.

Second, the reason it is non-negotiable is, as I have emphasized, its essential connection to the very idea of an ultimate cause, source, or explanation of things. The classical theist holds that nothing could be an ultimate explanation or cause unless it is absolutely simple or non-composite.

So, the stakes couldnt be higher. To reject divine simplicity is not merely to disagree with a particular philosopher or two. It is to reject the entire mainstream tradition in philosophical theology, and implicitly to deny the very possibility of ultimate explanation. Or, again, so the classical theist would argue. No doubt theistic personalists would disagree, but”especially given that theirs is, historically speaking, by far the minority position”an anthology like The Mystery of Existence should give a sense of the importance of the dispute between the two views.

A third point is that objections to divine simplicity of the sort raised by John and Robert in any event either miss the point or beg the question. Yes, the doctrine of divine simplicity is difficult to understand, but no more so than any other theory that requires us radically to abstract from the conditions of everyday material reality and apply concepts in novel and even seemingly paradoxical ways”as, of course, many philosophical and scientific theories do. (Wave-particle duality, anyone? Time as a fourth dimension, anyone?)

Hence, yes, if we carve up the conceptual territory the way the theistic personalist does, then of course divine simplicity will seem odd or even incoherent. So, suppose we took God to be one instance among others of the kind or genus person, who thus instantiates the same properties we do”power, knowledge, goodness, etc.”just to a higher degree. Since what we call power, knowledge, goodness, etc. in us are obviously different properties, and all of these properties are also in turn different from the substances in which they inhere, then it would follow that they are different properties in God and different also from the substance in which they inhere in his case. And so if we went on to say that Gods goodness, power, knowledge, etc. are all identical, this would, naturally, seem unintelligible.

But of course, that is simply not what Aquinas and other classical theists are saying. For instance, Aquinas does not start out by attributing power, knowledge, goodness, etc. to God in just the same sense that theistic personalists do, and then out of the blue tack on some strange stuff about simplicity and analogy. Rather, he starts by arguing for a cause of the world that is absolutely simple, pure actuality, etc. ( Summa theologia e I, qq. 2-3), then argues that what we predicate of this cause cannot, for that very reason, be exactly what we predicate of the things of our experience, but only analogues of what we predicate of those things ( Summa theologiae I, q. 4). Hence when we say that God has power and knowledge (for example) we dont mean that He instantiates the properties having power and having knowledge, just as we do. We mean that there is something in Him that is analogous to what we call power and knowledge in us, but that whatever this amounts to, it does not amount to his having just the same thing we do, or instantiating properties, or being a substance in which various distinct attributes inhere, etc.

Compare wave-particle duality. A physicist familiar with Aquinass theory of the analogous use of language might find it useful to say that quantum theory tells us that there is something in quantum phenomena that is analogous to what we call particles and analogous to what we call waves”but that it can only be analogous and not precisely the same as what we ordinarily call particles and waves, because being a particle in the usual sense excludes being wave-like, and vice versa. Aquinas is saying something comparable to that. He is saying that the arguments of philosophical theology show that there is a cause of all things that is absolutely simple, pure actuality, etc., and that (as he goes on to argue in the rest of Part I of the Summa) there is also something analogous to power, knowledge, goodness, etc. in this cause, but that precisely because the cause is simple, pure actuality, etc. What we are attributing to the cause is only analogous to, and not exactly the same thing as, what we attribute to ourselves.

Hence there is nothing any more suspect about Aquinass procedure than there is in quantum theory. And if quantum theory is acceptable despite being notoriously difficult to interpret, why should we expect a line of argument that deals with an even more fundamental question than quantum theory does”the question of why anything exists at all”to yield conclusions that are any less difficult to wrap our minds around? On the contrary, we should expect that the ultimate cause of all things will be extremely difficult for us to understand, rather than being”as the deity of theistic personalism is”essentially one of us (as the Joan Osborne song puts it).

Platonism and possibility

Let me make some brief remarks about Johns own preferred view of these matters, which is a kind of Platonism. John and Robert suggest that Aquinas view might be in the same ballpark as Platos notion of the Form of the Good, which can also be thought of as simple in the relevant sense. I would say that that is exactly correct”Aquinas is presenting a view which in its details is certainly importantly different from Platos, but is still in the same broad classical tradition. The view sketched out by John and Robert at the end of their piece is essentially representative of the Neo-Platonic branch of a larger tradition of which Aquinas represents the Aristotelian branch (albeit with some Neo-Platonic influences). So, the dispute between John and me is really a kind of family squabble. And regarding the contents of The Mystery of Existence , I suppose the point is that I wish John and Robert had included more selections from the members of our philosophical family.

(By the way, when I characterized Johns brand of Platonism as distinctive and somewhat eccentric”and those words were not meant to be pejorative, but merely descriptive”what I meant is this: John has sometimes described his position as entailing that creative value is the source of all things, and that the universe exists because of its ethical requiredness. I think that in substance what he is defending is essentially the sort of view one finds in Plato and Plotinus, but that the language in which he expresses it is arguably too modern and potentially misleading. At least since Hume, value connotes for most philosophers something that depends on someone who does the valuing, and thus seems essentially subjective or mind-dependent. And the ethical, for most modern philosophers, essentially connotes a property of the actions of rational creatures like us. Hence a position like Johns is”quite mistakenly, but understandably”bound to seem very strange and even unintelligible to most contemporary philosophers. More traditional Platonic expressions like the Form of the Good or even just the Good, while hardly common in contemporary philosophy, are in my view preferable since they better convey the objectivity or mind-independence of what John is talking about.)

Finally, I want to respond to one last objection raised by John and Robert:

Heres something that puzzled us. While Ed notes rightly how could anything actually exist unless it were in some sense a possibility? why does he seem to make God an exception to this rule? Even if God, instead of being a Person or a Being in a fairly straightforward sense, just is Subsistent Being Itself, doesnt it remain true that God exists? And if so, why does Ed write that all possibilities pre-exist as ideas in the divine intellect? For what about the possibility of Gods own existence? How could this possibility itself depend on the fact that God existed so as to be able to think about it?

This objection seems to presuppose that I take the realm of abstract possibilities to be the fundamental level of reality. The idea would be that everything that actually exists, including God, is in a sense dependent on a metaphysically more fundamental set of facts about what possibly could exist in the first place. And in that case, it would make no sense to say that possibilities depend on God.

But that is not my view. I would say that possibilities couldnt be the most fundamental level of reality, precisely because they are mere possibilities rather than actualities. Indeed, what is most fundamental can only be what is pure actuality in the sense described above. And what is pure actuality exists necessarily rather than in a merely possible way, precisely because it has no potentialities that could either be actualized or fail to be actualized. True, this ultimate cause is also possible in the trivial sense that, being existent, it can hardly be impossible. But its possibility follows from its actuality rather than being a precondition of its actuality. All other things that exist are mixtures of actuality and potentiality and of essence and existence, which is why their possibility precedes their actuality. And their possibility is grounded in their ultimate cause”the purely actual, absolutely simple divine source of all.

Obviously the metaphysical waters here are deep and I have hardly answered every question that might be raised about classical theism, even in this already-too-long article. But these are depths that need to be plumbed if we are fully to explore the question of why anything at all exists rather than nothing. Hence my wish that more readings from the classical philosophical tradition had been included in The Mystery of Existence . But as we have seen, John and Robert are not entirely unsympathetic to that tradition, and insofar as they have seriously grappled with its central concerns, they are its loyal sons. For their important contribution to the current debate, we are in their debt.

Edward Feser is the author of The Last Superstition: A Refutation of the New Atheism and Aquinas , and editor of Aristotle on Method and Metaphysics . He blogs about philosophy here .

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