In Defense of Christian Philosophy: A Response to Peter Leithart

The Triumph of St. Thomas Aquinas over Averroes (Benozzo Gozzoli, 1420-97)


I. Introduction

I am grateful to Peter Leithart for taking the time to interact with my book Divine Simplicity: A Dogmatic Account. In a recent post he has focused on the way in which philosophy plays a role in the articulation of divine simplicity and in Christian theology in general. Because I take his understanding of philosophy’s role to be problematic, I thought it fitting to offer a brief response. My aim in doing this is to clarify how we ought to think about philosophy’s role in Christian dogmatics and in theology proper especially.

Leithart’s eight critiques can be broadly classed into two main objections. First, he posits a conflict between philosophy and Scripture, between philosophy’s “distinction-mongering” and Scripture’s “poetic language,” and laments that in this conflict, philosophy too often tends to “bewitch us” and take us away from the pure and sufficiently precise words of Scripture. This claim can be discerned in his objections 3, 4, 6, and 8. This charge, while an old one in the history of Christianity, is either naïve or willfully misleading; every system of doctrine (including Leithart’s!) relies heavily on extrabiblical notions to expound Scriptural truth. To dismiss a concept as “extra-biblical” is mere Bulverism. The successful objection must demonstrate that it is actually “anti-biblical”: out of line with the results of good exegesis and leading us astray theologically.  In my view, Leithart has made little attempt at this latter argument.

Second, Leithart appears to understand philosophy not so much as an ordered inquiry into the truth of things (as the Aristotelian-Thomistic tradition that I defend would) and more as a set of arbitrary conceptual systems, any one of which might be equally serviceable (or harmful) to the theological task. On this basis, he seems to view my articulation of divine simplicity, using Thomistic philosophical tools, as little more than a conceptual parlor game that produces conclusions that no one but devotees of Thomas should have any reason to accept. This view of his appears in his objections 1, 2, 5, and 7. It betrays, I will argue, a fundamentally misguided understanding of what philosophy is and of the role it plays in the life of the Christian and the task of philosophy. In what follows, I will tackle these two clusters separately, rather than following the order of Leithart’s objections in blow-by-blow fashion.


II. Philosophy vs. Scripture?

Leithart’s first fundamental complaint is most fully articulated in Objection #3. Here he asserts, “Philosophy bewitches by her rhetoric,” making us “think that speaking in her dialect is more precise or profound than speaking in the poetic dialect of Scripture.” However, according to Leithart, “the Scriptural talk of God is the most precise and adequate language we can have. It’s God’s own talk about Himself.” But did Scripture itself instruct Leithart that precision is a desideratum for theological description? He clearly believes that it is a desideratum, but why? The call for precision is not explicitly spelled out in Scripture. It is a philosophical presupposition (i.e., one discovered by the natural use of the mind, without the mind being directly instructed on this point by supernatural revelation). Is it a good philosophical presupposition? To answer the question, one cannot appeal to particular statements of Scripture. One could argue that the Bible underscores the importance of understanding the truth about God, but moving from there to a call for precision in theological language will require the use of reason. Also, from where has the phrase “poetic dialect” come? Such a phrase cannot be lifted verbatim from Scripture. It is extrabiblical rhetoric. That does not make it bad, but it does not sit well with Leithart’s avowed approach to doing theology. Moreover, it is odd to deem poetic language more precise than metaphysical language. To clarify his meaning here, Leithart would have to explain what the word “poetic” means (and why he’s employing it in an unusual way). Doing this would require Leithart to flesh out his doctrine of Scripture with the use of terms and insights gleaned from the field of natural knowledge, for Scripture nowhere gives us a treatise on the nature of poetry, metaphor and so on.

Accordingly, Leithart’s third statement takes us to the heart of the problem with his post: when a theologian tries to claim the high ground by asserting that he or she is simply drawing from Scripture while his or her opponents are indulging in “philosophy,” the theologian is either being naïve or deceptive. Neither Leithart nor anyone else is simply repeating verbatim statements from Scripture. Leithart, along with everyone else, has to engage and draw upon knowledge developed by the use of the natural (and God-given) intellect. When someone is bent on trying to claim the aforementioned high ground, they are misleading their readers. Until someone like Leithart concedes that he is making use of extrabiblical knowledge to articulate his theological position, little can be gained from engaging in a debate about the doctrine of God and other particular topics. The first challenge is to dispel the naivete and establish some initial common ground.

Leithart’s fear of philosophy’s “bewitchments” can be recognized also in his fourth, sixth, and eighth charges, which I can address more briefly.


In Objection #4, Leithart suggests that use of philosophical language “depersonalizes” God. In particular, he takes issue with me talking about the “impinging of the divine essence in God’s historical action on different objects with different effects.” There is no problem with someone pointing out that, strictly speaking, it is not the divine essence as such but rather God himself, by his essential power, who performs actions and brings about effects. At the same time, I take it that there’s nothing problematic about any of the concepts involved in the phrase quoted by Leithart: “divine essence” (cf. Rom. 1:20; Gal. 4:8; Col. 2:9), “historical action,” the “objects” and “effects” of God’s action.


In Objection #6, Leithart warns about metaphysics becoming a “controlling paradigm” to which biblical teaching is forced to conform. He emphasizes that priority should be given to the biblical teaching. I would agree that our use of metaphysical language must be governed by exegetical judgments, but that is different from insinuating that any use of metaphysical language will automatically lead us away from faithful speech about God.


In Objection #8, Leithart cautions that philosophy “seduces us into distinction-mongering.” It sets up certain axioms that the Bible seems to contradict, so, in an effort to save the philosophical system, the philosopher-theologian ends up making certain distinctions to try to show how his or her preferred system is not threatened by Scripture’s teaching. I am sympathetic to Leithart’s concern here. There are times when a theologian has a preconceived theme or emphasis to which (in his or her mind) all else, even biblical teaching, must be subordinated. This can then lead to drawing forced distinctions that do not actually have a basis in reality or in God’s revelation. Though he was adamant about philosophy not driving our theological discourse, Karl Barth’s aversion to natural knowledge of God comes to mind here as an example of this sort of all-out commitment to avoiding clear scriptural teaching that challenges one’s presuppositions.

At the same time, distinctions are important. Any Christian who reads John 5:16-30 or 10:30, where Jesus’ describes himself as being equal to or one with the Father, and then John 14:28, where Jesus describes himself as being less than the Father, will wonder how such claims fit together. Unless pastors and other teachers of theology are prepared to observe some key distinctions here, Christian believers will remain confused and perhaps even headed down the road to heresy. There is no “one-size-fits-all” approach to how many distinctions are permissible in a given theological discussion. Whether distinctions are legitimate is a question that must be handled on a case-by-case basis.


III. Philosophical Parlor-Games?

Leithart’s second main complaint, I would argue, stems from a fundamental misunderstanding of what Christian philosophy is. His objections here manifest a casual disdain for a millenia-long inquiry into the nature of things, guided by confidence that the God who made all men by nature with a desire to know also blessed them with some capacity to know. Here I will work sequentially through Objections 1, 2, 5, and 7, the last of which finally gets us to the heart of the matter.

First, in Objection #1, Leithart observes, “Philosophies differ.” Yes, they do. But Leithart adds that I “forget the variety of metaphysical systems.” This by itself is not really a substantive critique, for Leithart hasn’t pointed out here where I exhibit such forgetfulness. Nevertheless, it’s worth mentioning that while there are different claims and systems present in the history of philosophy, that does not mean that all are created equal. Some are insightful and merit attention and contemporary retrieval.


In Objection #2, Leithart notes that I critique some recent authors who misuse the term “accident.” He claims that I have taken issue with their definition of this term when in fact it should not matter which definition is used, as long as one clarifies one’s definition of it and uses the term consistently. This is, unfortunately, a superficial reading of the problem involved here, and of the related points brought up in the book. As I’m sure Leithart would affirm, we use terms in the context of traditions and established patterns of speaking. If one chooses to use a term differently than one’s predecessors, one is obligated to make the reader aware of this.

The problem with the use of “accident” in some contemporary philosophical theology is that the authors do not sufficiently clarify what their definition is and how it relates to a classical Aristotelian definition.[1] Such authors sometimes insist that predicates like “Creator” or “Lord” are “accidents” or “accidental properties” that God comes to bear. They sometimes then use this line of thought to argue that older authors like Augustine and Aquinas were mistaken when they denied that there are accidents in God. There is a failure here to distinguish between this newer use of the word “accident,” in which, it seems, any predicate can be called an accident or a property, and an older use, in which an accident is a secondary “being” or “thing” that inheres in a subject and contributes to the subject’s perfection or completeness – a completeness that does not pertain to the subject just by virtue of being what it is. The reader is led to believe that Augustine and Aquinas were quite thick-headed on this matter, when in fact they used the term “accident” in a well-established and much more precise way. I discuss this on pages 187-8 of the book, but Leithart hasn’t noted the confusing ways in which the term “accident” has been used recently and how this confusion affects the assessment of older writers.

In addition, when noting that there are different definitions of “accident” being used, Leithart asks, “But who’s to say which definition of accident is ‘right’?” Well, it is of course possible to argue that the eight-letter English word “accident” might as well be used to signify any predicate that might be applied to a subject. But that is to miss the point. For even if the definition of a word is changed, there will still be a need for us to discuss the thing that was originally signified by the word. In this case, there will still need be a need to discuss not merely predicates in general but, more specifically, things that don’t exist on their own but have to exist in other things and end up serving either to fulfill or corrupt those things in which they exist. We could make up a new term if we wished to do so, but the discussion of the thing signified must go on and will require some terminology to facilitate it.


In Objection #5, Leithart states, “Philosophy makes us assume things are established that aren’t established.” Here Leithart has in mind the notion that “unity is superior to diversity,” which is his way of expressing the claim that all the perfections found in creation “pre-exist” in a more eminent and united way in God. Leithart questions why one would assume that unity is superior to diversity in this regard. I will suggest toward the end that this is simply one of those basic insights into the nature of reality that it is difficult for us to avoid. But for now, I am puzzled that he wonders about this given that I spend time in the book explaining why we should hold that God’s perfections are all really one in him. Briefly, if there were really distinct parts or perfections in God, then the aseity and ultimacy of God would be compromised. He could not draw together or compose those diverse parts or perfections for himself, for that would be a matter of self-causation. Yet he could not be composed by another, for there is no other before him. If someone is inclined to say that would-be diverse parts in God just necessarily would exist together, this is to reassign the ultimacy of God to an impersonal modal structure, a brute necessity that determines who God is. Precisely by doing that, one places God within a larger framework or philosophical system. Far better to emphasize that no one and nothing holds God together or establishes who he is. Each of God’s perfections just is God himself viewed from a particular angle.

It should be noted that when we discern that distinct things that are united to one another have come together or are held together somehow, we are not bowing the knee to the elaborate system of any one non-Christian philosopher. We are simply working with basic principles impressed upon our minds by the Creator through our experience of the structures of his world. In this connection, we should bear in mind that “philosophy” does not primarily signify the system of thinking advanced by any one philosopher (Plato, Aristotle, etc.). It properly signifies a knowledge attained by the natural use of the intellect or reason that is given to us by God.[2]

Leithart also objects to the assumption that individual parts are less than the whole of which they are parts. He claims that there are some “systems” according to which there are “multiple infinities” that come in “different sizes,” some of which are “part of other infinities” (like the set of positive numbers and the set of negative and positive numbers of which the positive numbers are a “subset”). (When it suits his purpose, Leithart seems prepared to give some credence to philosophical considerations.) According to Leithart, the implication is that it’s dubious to argue that there can be no parts in God since parts are less than the whole.

However, given the immateriality and spirituality of God’s being, there’s no good reason to think that such mathematical reflections on potential quantities should determine how we think about the divine attribute of infinity. In addition, the unnamed mathematicians invoked by Leithart misunderstand what infinity means. It means that the quantities under discussion would truly be without limit, having no endpoint at which one could conclude that there were less numbers of one sort than another. His accompanying suggestion that we cannot tell whether an individual part is less than a whole is an affront to the natural principles with which all human persons operate, albeit often only implicitly. Certainly the notion that an individual part is less than a whole is assumed where the apostle Paul assures his readers that “all the fullness of deity” dwells bodily in Christ (Col. 2:9), not merely some “part” of deity beyond which (per impossibile) there would be “more” of the divine fullness to be sought by Christian believers.


Finally, in Objection #7, Leithart argues that translating biblical teaching on God’s aseity into a Thomistic framework and concluding that it entails divine simplicity doesn’t actually teach us anything about God. It only tells us that, if we transpose biblical teaching into this framework, it will yield the conclusion that God is simple. Leithart wonders if the biblical teaching actually somehow challenges the framework into which the biblical teaching is being transposed. This is in fact a very important question, and I am glad to have had the opportunity to think further about how to make the point that needs to be made.

In the book I stated that the use of Aristotelian or Thomistic metaphysical concepts to articulate Christian doctrine is to some degree an ad hoc decision, helpful but not absolutely necessary. This needs clarification, however. This move is an ad hoc decision in that it’s possible to articulate Christian doctrine without formally invoking concepts like “essence,” “substance” and so on. Instead of saying, for example, that in the incarnation there is one hypostasis subsisting in two distinct natures, one can say that there is just Jesus and not someone else and that Jesus always remains both truly God and truly human.

However, the fact that the use of the metaphysical language is not absolutely necessary does not mean that the metaphysical resources in question are detached from reality. It does not mean that what they offer us is just a set of coherent rules for saying things – rules that we might either take or leave. On the contrary, the classical metaphysical tradition developed by Christian thinkers like John of Damascus, Thomas Aquinas or the early Reformed theologians and philosophers involves a knowledge of how things are. Indeed, it is fundamentally an exposition of things human beings know to be true prior to engaging in any formal academic work. For example, things do have natures by virtue of which they are similar to other things. There really are substances in which accidents inhere. It is true that a whole is greater than any of its individual parts. The ad hoc nature of the decision to incorporate Aristotelian philosophical resources concerns the fact that explicit use of these concepts is not absolutely necessary for articulating doctrine. It does not concern the truthfulness or explanatory fecundity of the basic natural insights into the created order that are unpacked in the Aristotelian tradition. The notion that a whole is greater than its parts, for example, is true and is implicit in a statement like the one found in Colossians 2:9. As we seek ways to express what God is like according to scriptural teaching, we should look to this philosophical tradition, not Kant or Hegel, because it sheds light on reality. Of course, we will have to clarify how certain things that are true in the case of creatures are not true in God’s case, but that is precisely one of the ways in which someone like Aquinas puts this tradition to good use in saying, for example, that God’s attributes are not accidents but really are just God himself.


IV. The Quest for Wisdom in the Light of Christ

Leithart’s reflections provide a helpful opportunity to clarify what we do and do not have in mind when we think about the place of philosophy in Christian theology. However, he is wrong (either naïve or misleading) in suggesting that he manages to draw upon Scripture alone in articulating Christian doctrine. Until we recognize that all of us use extrabiblical notions to expound the material content of Scripture, debate on a particular topic like divine simplicity will have to be postponed. Just as crucially, Leithart seems to think of philosophy solely in terms of elaborate systems of thought that no doubt in certain places contain errors. However, philosophy is fundamentally a knowledge or study of things discoverable by natural reason without necessarily being informed by supernatural revelation. It is a setting forth of things typically known implicitly by ordinary human beings (like the difference between an efficient cause and a final cause or the law of non-contradiction). What contemporary Christian theology needs, I would suggest, is a renewal of the traditional Protestant commitment to Scripture as the cognitive principle of theology and to reason or philosophy as a subordinate instrument for expounding what Scripture teaches.


Dr. Steven J. Duby is Assistant Professor of theology at Grand Canyon University.  He is the author of Divine Simplicity: A Dogmatic Account (T&T Clark, 2017), and his research interests focus on theology proper and Christology. 


[1]See, e.g., William F. Valicella, “Divine Simplicity: A New Defense,” Faith and Philosophy11 (1994), 512-13, 517; Jay Wesley Richards, Untamed God: A Philosophical Exploration of Divine Perfection, Simplicity,and Immutability(Downers Grove: InterVarsity Press, 2003), 231-40; Paul Copan and William Lane Craig, Creation out of Nothing: A Biblical, Philosophical, and Scientific Exploration(Grand Rapids: Baker, 2004), 177-8.

[2]Compare Francis Turretin, Institutes of Elenctic Theology, I.13.4.

Read more about the proper relationship of philosophy and theology--the quest for wisdom in the light of Christ.