Thinking about Philosophy: A Lesson from Thomas Aquinas
As is well known, Thomas Aquinas is a towering figure in the history of Western thought. His acclaim is well deserved; there are many insights to be gleaned from reading his works, and even where he is mistaken, his errors are often instructive. Among the places where Aquinas is particularly helpful is his understanding of how to use philosophy in the service of theology. This being so, the following remarks will briefly discuss how he characterizes philosophy and its relationship to theology. We will see that the great scholastic doctor is in large part an excellent guide, though he does make one notable error.
Before looking at what Aquinas said, it may be prudent to make a few comments about Aquinas and Lutheranism. Sometimes Lutherans are a bit hesitant to engage with Aquinas. This is because he is often seen as the quintessential Roman Catholic theologian, and also because Luther had some negative things to say about him. These factors put him under a cloud of suspicion, and sometimes Lutherans steer clear of him even when they are not generally averse to medieval theology.
There is much that could be said about this topic, but hopefully a few brief points will suffice. First, it is proper to say that Aquinas was simply an outstanding medieval Christian thinker. He didn’t become the quasi-official theologian of Roman Catholicism until the nineteenth century, long after the Reformation. Second, Luther did not have much firsthand knowledge of Aquinas’s work, and the secondhand accounts he had been exposed to were not always accurate. One result of this is that Luther believed that Aquinas was basically a semi-Pelagian with respect to the role of grace in salvation. But the truth is that Aquinas’s soteriology is highly Augustinian. He did not believe in sola fide, but he did believe in sola gratia. If Luther had understood this, his comments on Aquinas might have been more favorable.[i]
It's also true that later Lutheran theologians in the seventeenth century regularly engaged with Aquinas and cited him frequently, often because they approved of something he said. One Lutheran theologian, by the name of Johann Dorsche, wrote a book of several hundred pages arguing that Aquinas would make a better Lutheran than a Roman Catholic.[ii] So there is a precedent for Lutherans studying Aquinas.
In any case, I want to look at one of Aquinas’s lesser known works, in which he briefly deals with the question of the value and utility of philosophy. This is his commentary on Boethius’s On the Trinity. Boethius was a Christian writer who lived in the years following the fall of Rome and had a great influence on medieval theology. Aquinas addresses many topics in this commentary, but I just want to focus on the third article of question two, which is titled “Is It Permissible to Use Philosophical Reasoning and Authorities in the Science of Faith, Whose Object Is God?” As one might expect, in this article Aquinas makes some important points about how to think about faith and reason.
Regarding what philosophy is concerned with, Aquinas takes the position that philosophy studies the book of creation, or God’s creatures as they can be known by our natural powers. He quotes Augustine, who said “I shall not be sluggish in seeking after the substance of God, whether through his Scripture or through his creature.”[iii] Aquinas then adds that “the knowledge about creatures is set forth in philosophy.”[iv]
Concerning the question of whether it is legitimate for theologians to use pagan philosophy, Aquinas affirms the view that all truth is God’s truth. This is a perspective that was commonly expressed in the early church. Aquinas again quotes Augustine, who in his book On Christian Doctrine wrote the following: “If those who are called philosophers have said things by chance that are true and in agreement with our faith, we must not only have no fear of them but appropriate them for our own use from those who are their unlawful possessors.”[v] This is a view that Aquinas wholeheartedly endorses, and it’s one that I think all Christians need to affirm. He adds that “secular wisdom is said to be opposed to God in regard to its abuse, as when heretics misuse it, but not in regard to its truth.”[vi]
Aquinas affirms that there are three ways to use philosophy in theology. The first is to “demonstrate the preambles of faith, which we must necessarily know in the act of faith.”[vii] For Aquinas, a preamble of faith is not an article of faith per se, but it is something that can be known through reason that faith takes for granted. He goes on to say that “such are the truths about God that are proved by natural reason, for example, that God exists, that he is one, and other truths of this sort about God or creatures proved in philosophy and presupposed by faith.”[viii] So, for Aquinas, the truth that God is triune is an article of faith, but the fact that God exists is classified as a preamble of faith.
The second use, for Aquinas, is “to throw light on the contents of faith by analogies, as Augustine uses many analogies drawn from philosophical doctrines in order to elucidate the Trinity.”[ix] Using analogies from creation to provide some understanding of the Trinity is always a somewhat risky endeavor, because such analogies often obscure the truth as much as they clarify it. But Aquinas’s point is simply that analogies based on created and earthly things can sometimes serve to illuminate or illustrate spiritual truths. For example, the image of a red hot piece of iron being used to illustrate the communication of attributes in the incarnation.
The third use is “to refute assertions contrary to faith, either by showing them to be false or lacking in necessity.”[x] So, in other words, showing that they can’t be true or at least might not be true. Philosophy can certainly provide help to faith by showing that the arguments of unbelievers are invalid or unsound. He also says in this article that “seeing that a teacher of Sacred Scripture must at times oppose the philosophers, it is necessary for him to make use of philosophy.”[xi] Now it’s certainly true that Christians can and should tell unbelievers what the Scriptures say on a given topic. But because unbelievers are probably not going to be moved by what Scripture says, it is generally beneficial for Christians, and especially pastors, to have some basic knowledge of the weapons philosophy offers to combat atheism, skepticism, and relativism.
Regarding all of these uses, Aquinas asserts that “those who use the works of the philosophers in sacred doctrine, by bringing them into the service of faith, do not mix water with wine, but rather change water into wine.”[xii] I don’t know that I would put things this way, since it seems to efface the distinction between philosophy and theology. But we can take his point well by acknowledging that it is true that philosophy can and should be consecrated to God and put into the service of theology and the church.
Aquinas clearly and rightly thinks that philosophy is helpful to Christians. He goes on, however, to offer a word of caution about the use of philosophy. He writes that “those who use philosophy in sacred doctrine can err in two ways. In one way by making use of teachings that are contrary to the faith, which consequently do not belong to philosophy but are a corruption and abuse of it. Origen was guilty of this. In another way by including the contents of faith within the bounds of philosophy, as would happen should somebody decide to believe nothing but what could be established by philosophy. On the contrary, philosophy should be brought within the bounds of faith.”[xiii]
These warnings are indeed important. The first error is what happens when theologians employ bad or false philosophy and allow that philosophy to have a role in shaping what they teach and profess. We see this over and over again in modern theologies. It could even be the case that a theologian takes a philosophical idea that is true in a certain sense or respect but then misapplies it to something that he shouldn’t. I would say Aquinas does this himself with regard to transubstantiation, to give one example.
The second mistake he cautions against is what happens when people become thoroughgoing rationalists and won’t accept anything as true that they have difficulty understanding or proving. A good historical example of this is early modern deism. The deists were willing to accept certain religious tenets but only because they supposedly were entirely rational and not based on testimony. They therefore believed in God’s existence, and in the natural law, and in the reality of the soul, but that was about it. No divine Christ, no atoning cross, no glorious resurrection. We also, once again, see many traces of this attitude in modern theology.
I think Aquinas is right about these points, and I think we need to follow him on these matters. That being said, we shouldn’t follow Aquinas on everything pertaining to philosophy. There is one thing he says in this article that I think is slightly off base. It’s a subtle error, and easy to miss, but it can and usually does have far-reaching consequences. It’s a view that most Christians throughout history would probably regard as unproblematic. But there is a problem, and we need to avoid it.
What Aquinas says is the following: “The light of faith, which is imparted to us as a gift, does not do away with the light of natural reason given to us by God. And even though the natural light of the human mind is inadequate to make known what is revealed by faith, nevertheless what is divinely taught to us by faith cannot be contrary to what we are endowed with by nature. One or the other would have to be false, and since we have both of them from God, he would be the cause of our error, which is impossible. . . . It is impossible that the contents of philosophy should be contrary to the contents of faith, but they fall short of them.”[xiv]
Now this probably sounds quite reasonable, and many Christians in history have affirmed this view. Many voices concur in saying that the truths of revealed theology are not contrary to human reason but above it. We Lutherans must agree that there is a sense in which Aquinas is right. Faith indeed does not do away with reason or make reason irrelevant, and it’s also the case that from God’s point of view all truth certainly coheres, and everything is intelligible. For God nothing is mysterious or paradoxical. So what’s the problem, then?
The issue I see with Aquinas’s statement is that God’s vantage point is not ours. We have the viewpoint of fallen beings whose natural powers have been weakened and are really only adept at dealing with earthly or temporal realities. By using reason we are able to discover the truth about things pertaining to the natural world or the book of creation—including the fact that it was created—but reason reaches a limit when it comes to spiritual or divine truths—what we might call the deep or hidden things of God. Our ability to make sense of things at this level is not guaranteed. Our ability to correctly perceive that assertions are ultimately irreconcilable is in doubt.
This weakness of fallen reason is why we must be very careful in how we apply reason to God’s revelation to us in Scripture. For Scripture reveals some of these hidden things of God, and some of them are deeply mysterious. If we approach them with the assumption that everything must cohere according to the principles of our reason, we will run into problems. For one thing, we will not end up taking the whole counsel of God seriously. We will ignore certain passages, or give them highly implausible interpretations (such as when the Calvinist says all people means all kinds of people). Secondly, we will implicitly demote Scripture from being our highest authority. For if something Scripture says must meet our standards for consistency to be taken at face value, then ultimately reason ends up with the last word. It becomes an equal partner to theology, not a dutiful handmaid.
For someone who truly affirms sola Scriptura and understands that revelation must trump the dictates of reason, Aquinas’s statement cannot be allowed to stand. Nevertheless, someone may object and allege that if one does not demand logical coherence in the interpretation of Scripture, then all manner of nonsense will follow. For example, there is anthropomorphic language about God in the Bible. Do we need to take this at face value? Are we not able to exercise any kind of discernment, or ever say that the Bible shouldn’t be taken literally?
To respond to this objection we need to clarify a few points. First, Lutherans don’t claim that Scripture ever truly contradicts itself. What we say is that sometimes we cannot see how two or more things that Scripture affirms are consistent. But we don’t say there is or could be a contradiction, as if we were to both affirm something and deny it in the same sense. That would truly be nonsense and devoid of meaning, but that’s not what we are arguing for.
Second, we don’t say that reason has no role to play in interpreting Scripture. Reason has to be utilized to understand the grammar and vocabulary of the biblical languages. It has to be used to grasp the historical context of the biblical authors. We use it to draw inferences from what is said, like when we conclude on the basis of Scripture that God is a Trinity of equal persons. We also need reason to use the rule of faith or analogy of Scripture to interpret more obscure passages in light of more lucid passages. One thing this requires is discerning what counts as a clear passage. Another thing it requires is discerning what is supposed to be treated as figurative language and what is meant to be literal. When Lutherans investigate such things, however, we are looking to Scripture itself to give us the answers. We are not approaching Scripture with the intention of erecting some theological grid into which every passage must neatly fit. We are not looking to put Scripture into a logical straitjacket.
With respect to the issue of anthropomorphic language, I believe that the whole witness of Scripture makes it evident that anthropomorphic language about God needs to be seen as non-literal. This is because what Scripture affirms about the differences between God and his creatures would be directly contradicted if this anthropomorphic language were taken literally. It would be equivalent to affirming both that God is unchanging and changing, or that God is spiritual and corporeal. This would simply make no sense. It wouldn’t be a mystery; it would be gibberish. Therefore either the anthropomorphic affirmations or the non-anthropomorphic affirmations must be seen as figurative. But if the non-anthropomorphic statements are seen as the figurative ones, then we are basically saying that God has the attributes of a creature, and this clearly violates the rule of faith. If anything is a clear and established scriptural truth, it is that God is not a creature.
What we see, then, is that to criticize Aquinas’s statement does not create insuperable problems. It requires us to be careful and to utilize sound exegetical principles, but it doesn’t lead to a flood of nonsense. We can still distinguish between mysteries and outright contradictions, and we must do so. The problem with Aquinas’s view (and those like it) is that it generally does not maintain this distinction as we do. As a result, genuine mysteries are lumped together with contradictions and dismissed or misinterpreted. We must be more subtle in how we approach Scripture, for only then will we be fully receptive to what God is telling us within its pages.
In sum, Aquinas can help us to clarify the most important elements of a Lutheran view of the relationship between reason and faith or philosophy and theology. Perhaps the key thing to remember is that we must always keep philosophy in the role of a servant, never an equal partner to theology. Aquinas acknowledges this as his goal as well, but we must be more consistent and diligent than he himself is in this regard.
[i] For two very helpful studies of Luther and Aquinas by Denis R. Janz, see Luther and Late Medieval Thomism: A Study in Theological Anthropology (Wilfrid Laurier University Press, 1983), and Luther on Thomas Aquinas: The Angelic Doctor in the Thought of the Reformer (Franz Steiner Verlag, 1989).
[ii] For a discussion of Dorsche and Aquinas, see Benjamin T. G. Mayes, “Seventeenth-Century Lutheran Reception of Aquinas” in The Oxford Handbook of the Reception of Aquinas, eds. Matthew Levering and Marcus Plested (Oxford University Press, 2021), 222-254.
[iii] Augustine, quoted in Thomas Aquinas, Faith, Reason and Theology, trans. Armand Mauer (PIMS, 1987), 47.
[iv] Aquinas, 47.
[v] Augustine, quoted in Aquinas, 48.
[vi] Aquinas, 50.
[vii] Aquinas, 49.
[viii] Aquinas, 49.
[ix] Aquinas, 49.
[x] Aquinas, 49.
[xi] Aquinas, 48.
[xii] Aquinas, 50.
[xiii] Aquinas, 49.
[xiv] Aquinas, 48.
Nathan Greeley is managing editor of The Conservative Reformer.