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As John Franklin Johnson points out in the following article, it is quite a common opinion, in both philosophical and lay circles, that a true philosophical enterprise must begin with no information in view other than that which can be generated by the philosophical enterprise itself. In other words, “Christian philosophy “ is a contradiction in terms because the Christian knows from Revelation the answers to many of the most important questions he can ask. This point of view, argues Johnson, arises from a misunderstanding (or perhaps merely an unnecessary restriction) of the meaning of philosophy and, equally to the point, of theology. Turning to the pre-eminent Christian philosopher, Thomas Aquinas, Johnson nds some first principles which make it clear that Christians can really do philosophy after all.

Perhaps no other issue has evoked such argument between philosophers and theologians-at least from among those in the two “camps” who take the work of the other seriously-than the one as to whether or not philosophical investigation undertaken by the Christian is as strictly “philosophical” as that of the thinker who endeavors to discard his faith and engage in “pure” philosophizing. The question focuses, as Anton Pegis has suggested, on one of the primary problems of a “Christian philosophy. “(1)

Certainly more than one philosopher has believed that the adjective in the phrase “Christian philosophy” seems to negate the noun. Bertrand Russell, for example, has written of St. Thomas Aquinas that his “appeal to reason is, in a sense, insincere, since the conclusion to be reached is fixed in advance.” There is, he adds, “little of the true philosophical spirit in Aquinas. Before he begins to philosophize, he already knows the truth        (2) The attitude of Martin Heidegger is the same. He considers authentic philosophical reflection impossible for the Christian. To ask why there is something rather than nothing is to put the totality of the real in question in order to make it fully intelligible. Heidegger contends that the Christian thinker cannot give himself over to such an enterprise: if research is to be serious, one must not be convinced he possesses the answer before starting the search. But, of course, for the Christian there is no doubt-God stands at the origin of the world, creating and sustaining it. Thus, Heidegger echoes the sentiment of Russell; indeed, the term “Christian philosopher” is as nonsensical for him as the term “square circle.”(3)

It is the primary contention of this essay that such criticisms are ill-founded because they rest on a fundamental misunderstanding of the role of theology-or more accurately sacra doctrina-in the philosophy of St. Thomas. This contention will be developed, first, by a brief indication of the general relationship between philosophy and theology in Aquinas, and, second, by an attempt to summarize what Thomas means when he refers to sacra doctrina. Such a glimpse into the Thomistic conception of Christian theology which serves as a locus for his view of faith reveals a relationship between faith and reason in Thomas which is quite distinct from the one implicit in the remarks of Russell and Heidegger.(4)


In Science and Wisdom, Jacques Maritain laments the fact that the intellectual order of the medieval world has been fractured. “The modern world,” he writes, “has not been a world of harmony between forms of wisdom, but one of conflict between wisdom and the sciences, and it has seen the victory of science over wisdom.”(S) But in the Thomistic perspective, says Maritain, there are properly three sorts of wisdom hierarchically ordered: infused wisdom or the wisdom of grace, theological wisdom, and metaphysical wisdom. Below these, the philosophy of nature exemplifies a type of imperfect wisdom, which is superior, however, to the special sciences, which are not wisdom in any sense of the word. Unfortunately, Averroism and Cartesianism separated philosophical wisdom from theological wisdom. Man was, as it were, “cut into two parts, one being man according to pure nature, with his philosophic wisdom; the other being man according to grace and faith, with his theological wisdom. “(6) Philosophy became disengaged from the “spirituality which came down to it from the heights of the soul. “(7) The name “wisdom” came to be applied only to philosophy and science came to preponderate over wisdom. In other words, the upshot of this entire development was that, in separating philosophy from theology, the possibility of theology as a science was denied.

The unity which Maritain longed for serves as a key to the relationship established by St. Thomas between philosophy and Christian theology. There is, in that relationship, a unity between two sources of knowledge-what Gilson alludes to as the twofold certitude of philosophy and revelation.(8) In the light of this unity, far from seeing in revelation the downfall of true philosophy, Thomas viewed philosophy as a kind of praeparatio evangelica by which the minds of men were prepared to receive divine truth.

This notion is perhaps most clearly elaborated in the initial book of the Summa Contra Gentiles. The object of wisdom, or first philosophy, Aquinas argues, is the end of the universe. A wise man, therefore, is one who can arrange things as they ought to be arranged. That is to say, to dispose it with a view to its end:

…they are to be called wise who order things rightly and govern them well. Hence, among other things that men have conceived about the wise man, the Philosopher includes the notion that `it belongs to the wise man to order’. Now, the rule of government and order for all things directed to an end must be taken from the end. For, since the end of each thing is its good, a thing is then best disposed when it is fittingly ordered to its end. And so we see among the arts that one functions as the governor and the ruler of another because it controls its end. Thus, the art of medicine rules and orders the art of the chemist because health, with which medicine is concerned, is the end of all the medications prepared by the art of the chemist… .They are therefore said to be wise with respect to this or that thing; in which sense it is said that `as a wise architect, I have laid the foundation’ (I Cor. 3:10).(9)

Moreover, since the end of an object is the same as its principle or cause, rational knowledge has for its object the study of first causes: “It belongs to the wise man to consider the highest causes.”(10)

Thomas then takes under consideration that which is the first cause or the final end of the universe. The final cause, he maintains, is that which its author, in making it, has in view. Since it can be demonstrated that the first author of the universe is an intelligence, the end which he has in view in creating it must be the end of intelligence which is truth.

Now, the end of each thing is that which is intended by its first author or mover. But the first author and mover of the universe is an intellect, as will be shown later. The ultimate end of the universe must, therefore, be the good of an intellect. This good is truth.(11)

Thus, truth is the final end of the universe; and since the object of first philosophy is the ultimate end of the universe, it follows that its proper object is truth. But the disposition of things in the order of truth is the same as that in the order of being-being and truth are equivalent. A truth, Thomas reasons, which is to be the source of all truth can be found only in a being which must be the first source of all being. In a word, the true object of metaphysics or first philosophy is God. Philosophical inquiry is almost totally ordained to the cognition of God as its end.

In chapter three of Book I of the Summa Contra Gentiles, Aquinas moves to the way in which divine truth is to be made know. Man has at his disposal two means. The first means, of course, is human reason. The natural reason is capable of grasping such truths as the existence of God, that He is one, and the like. In fact, Aquinas observes, such truths about God have been proven demonstratively by the philosophers. The issue, rather, is whether the reason of man is an instrument sufficient to reach the goal of metaphysical inquiry, namely, the divine essence. Thomas concludes that it is not. It is evident that certain forms of knowledge concerning the nature of God exceed the power of human understanding:

That there are certain truths about God that totally surpass man’s ability appears with the greatest evidence. Since, indeed, the principle of all knowledge that the reason perceives about some thing is the understanding of the very substance of that being.. .it is necessary that the way in which we understand the substance of a thing determines the way in which we know what belongs to it. Hence, if the human intellect comprehends the substance of some thing, for example, that of a stone or of a triangle, no intelligible characteristic belonging to that thing surpasses the grasp of the human reason. But this does not happen to us in the case of God. For the human intellect is not able to reach a comprehension of the divine substance through its natural power. For, according to its manner of knowing in the present life, the intellect depends on the sense for the origin of knowledge; and so those things that do not fall under the senses cannot be grasped by the human intellect except in so far as the knowledge of them is gathered from sensible things.(12)

Perfect knowledge, therefore, consists in deducing the properties of an object by using its essence as the principle of the demonstration. Accordingly, the mode in which the substance of each thing is known to man determines the mode of the knowledge which he can have of the thing. God is a purely spiritual substance; man’s knowledge, on the contrary, is only such as a being composed of a soul and a body can reach. It originates necessarily in sensation. The knowledge man has of God is only such as a person starting from sense data can acquire of a being which is purely intelligible. Thus, the understanding of man, resting upon the testimony of his senses, can indeed infer that God exists, but it is evident that a mere examination of sensory objects, which are the effects of God and therefore inferior to him, cannot bring man to a knowledge of his essence.

This basic limitation of human reason leads Thomas to a second means man has in attaining the object of first philosophy: divine revelation. The necessity of revelation is stressed by him in the first part of the Summa Theologiae where Aquinas argues that if the end of man is none other than God and man must possess knowledge of his end to be able to order his intentions in relation to it, then revelation was necessary in order to bring to his knowledge a certain number of truths which are incomprehensible to the light of reason.(13)

Man has, then, a twofold certitude: Aquinas thinks that the ultimate object of both philosophical inquiry and theological inquiry is one and the same. There is, to be sure, an explicit and formal distinction between philosophy and theology for St. Thomas, but yet there is essential agreement. The knowledge of the first principles evident to the mind has been implanted in man by God, who is the author of his nature. The principles of human knowledge are part of divine wisdom and thus one should trust implicitly the natural light of reason.


The foregoing discussion of the general relationship between philosophy and theology in St. Thomas introduces, however, a crucial problem of terminology. And perhaps it is this problem which constitutes the basis for so many misleading interpretations of the Thomistic position on that relationship. The crux of the problem is that Thomas very seldom uses the word “theology”. Indeed, in the entire introduction to the Summa Theologiae he employs the word only twice. The first time the reference is precisely not to what one commonly understands by theology, but to the fact that Aristotle had called his “first philosophy” by the name of theology.(14) But this, as Aquinas will subsequently note, is different in kind (secundum genus) from the theology which pertains to sacram doctrinam.(15) The second mention of the term is connected with a simple reference to the etymology of the word which is said to indicate sermo de Deo-talk about God.(16)

Always and invariably, then, the discussion in the introductory question of the Summa turns not on the nature and meaning of “theology”, but on the nature and meaning of sacra doctrina. This is absolutely crucial to a proper understanding of the Thomistic perspective on philosophy and Christian theology. The kind of theology he is talking about has little in common with the philosophical knowledge of God except its object. The latter is roughly equivalent to what one calls natural theology; the other is appropriately called “revealed theology” or sacred teaching. Philosophy is the cognition of God such as man can obtain it; sacred teaching proceeds from God and it imparts to man something of God’s own self-knowledge so that through faith there is in man a part of the divine knowledge God has of Himself. This accounts for the fact that any investigation of philosophy and Christian theology must involve a close analysis of what theology, in the uniquely Thomistic sense of the word, is.(17)

The most efficient way to approach this task is to examine the ten articles of the first question of the Summa where Aquinas deals extensively with the domain of sacra doctrina. This procedure yields, in turn, three fundamental emphases.(18)

First, St. Thomas discusses the necessity of sacred teaching. The objections set forth in the first article attempt to exhibit the superfluity of theological teaching distinct from philosophy by contending that philosophy or science covers the whole of human thought.(19) Yet, against this all-sufficiency of philosophy, as noted in the first segment of this essay, Thomas maintains that a further doctrine is required. The truths which concern the supernatural end of man are beyond his rational comprehension. Moreover, Thomas argues, even in regard to those truths about God which are not beyond the reach of reason, it was necessary that man be instructed by revelation. Few men, Thomas realized, attain the knowledge of this kind of truth about God, and then only after a long period of study and with an admixture of error. Hence, in order that the salvation of men could be attained in a more certain manner, it was necessary that they be instructed in divine things through divine revelation. Therefore, besides the philosophical disciplines which carry on their investigations by way of human reason, another teaching was mandated-sacra doctrina.(20)

A second component of the Thomistic concept of sacred teaching deals with the possibility of applying the term “science” to sacra doctrina. In order to approach this question Aquinas delineates two kinds of science: some, he says, work from premises recognized in the innate light of the mind (e.g., arithmetic, geometry, etc.); others work from premises recognized in the light of a higher science. Optics, for instance, begins from principles marked by geometry and arithmetic.(21) The primary difference between these two kinds of science is that in the first the principles are self-evident while in the second they are reducible to those of a higher science. Thomas then contends that sacred teaching is a science in the manner of the second kind, “for it flows from founts recognized in the light of a higher science, namely God’s very own which he shares with all the blessed.”(22)

At this juncture, as Gilson has commented, Thomas is effecting a transposition. The notion of science applies to sacred teaching only in an analogical way. Since it proceeds from principles of its own, sacred doctrine truly is a science, but with one difference. The principles of the higher sciences from whose conclusions these sciences themselves proceed are known by the natural light of the intellect whereas sacred teaching proceeds, following the light of the intellect, from principles revealed by God.(23) This accounts, it would seem, for the previous statement of Aquinas that the theology of the philosophers and the theology that is part of sacra doctrina do not belong to the same genus. The theology that is a part of sacred teaching enjoys the unique privilege of proceeding from principles made known by revelation, and succeeding articles endeavor to make this truth as clear as possible.

In the third article, Thomas argues that sacra doctrina is one science. He appeals to the principle that the unity of a potency or habit must be judged from the unity of its formal object. For example, a man, a donkey, and a stone, though different things, agree in that which is the formal object of sight, that which is colored. The comparison applies to the case of sacred doctrine because it borrows its principles from the science of God made known to man by revelation. Scripture deals with a variety of objects but there is a formal object involved. The ratio formalis objecti is God’s revelation of Himself in scripture. Therefore, whatever is revealed by God falls under the formal object of one and the same science. Further, sacred doctrine treats of the creator as well as of the creatures not equally (for if it did, there would not be one class of objects) but of God primarily. Thus, sacred teaching is one, and therefore a science. In reply to the objection that because Christian theology discusses angels as well as bodily creatures and human conduct it is not a unified science, Thomas contends that Christian theology stands at the center of all such philosophical disciplines, yet dominating them because it is able to unite them in its own unity.(24) This is a subtle albeit significant point. Every subject about which something has been revealed by God is included in a class. There is really nothing that philosophy can say which is not related to some object of a possible revelation; therefore, sacra doctrina can treat objects which are the subject matter of philosophical sciences. Divine science is the one science of everything-an imprint on man of God’s own knowledge.(25)

A third and final theme in the discussion of sacred teaching which is developed in the first question of the Summa is what Gilson, for example, has termed the “transcendence” of theology.(26) Article four, for instance, asks whether sacred teaching is a practical science. Thomas responds that sacra doctrina is not chiefly concerned with what man can do, as is the case with moral science, but rather with God, who is man’s maker. However, being the supreme science, sacred teaching does not exclude practical knowledge. Other sciences are practical or speculative, but a science that is in the mind of man as a stamp of the divine science cannot suffer such circumscriptions. In other words, everything goes back to the same point of departure: it considers in each thing the same formal object.(27)

The important implications of this idea are elucidated in article five. Thomas addresses the question, “whether sacred teaching is of greater value than other sciences.” He answers that sacred doctrine is indeed more valuable. Since it is both speculative and practical, embracing both in the divino lumine it would naturally be higher than all other sciences. As speculative, it is more certain than all the others which are known through the fallible light of human reason, while the certitude of sacred doctrine is derived from divine knowledge. Too, the kind of truth known in sacred doctrine transcends all human truths. Since sacred teaching is aimed toward eternal beatitude it becomes the most important of practical sciences.(28)

This leads Aquinas to further underscore the superiority of sacred doctrine in article six by asserting that it is the wisdom above all human wisdoms, an authority that adheres to it because its concern is with the highest cause of the universe.

In article seven, Thomas discusses the subject of sacred teaching. The subject of science is related to science as object to habit or potency. The object of some potency or habit is properly assigned as the object under that aspect according to which all things are related to the habit or potency; for example, man and stone are related to the potency of sight in so far as they are colored; hence, that which is colored is the proper object of sight. All things, Aquinas reasons, are treated in sacred doctrine under the aspect of God, either because they are God Himself, or because they are ordered to God as to their principle and end. It follows, then, that God is the subject matter of Christian theology. Everything discussed in sacred doctrine is discussed sub ratione Dei; the principles of sacred doctrine are the articles of faith, and faith is about God.(29)

Having arrived at a satisfactory definition (quod quid est) of sacra doctrina, Thomas next considers this “revealed theology” in its method or modality (de modo). He asks in article eight whether sacred doctrine is argumentative or whether it adduces proofs on its own behalf. In response, he says that proofs are utilized in two primary ways: to argue from one truth of faith to another and to refute those who would contradict faith among believers by demonstrating the fallacy in their reasoning. No lower science argues to defend its principles. But, of course, sacred doctrine is a wisdom; therefore, it not only argues to conclusions but also defends its own principles, which further demonstrates the philosophical character of sacra doctrina.(30) In fact, Aquinas states that when arguing against Jews and heretics the principles admitted by them can be used effectively to prove the veracity of the entire faith. (This is an important apologetic strategy.)

In articles nine and ten, St. Thomas quickly rounds out his discussion by pointing to certain unique features of sacra doctrina which need to be understood to avoid confusion. The first such consideration is whether sacred doctrine should use metaphors or symbolic language. On the one hand, metaphors and poetic language are not befitting the noblest of all doctrines and such language tends to obfuscate the truth that sacred doctrine intends to teach. But on the other hand, Christ used parables, poetry, and metaphors. Thomas concludes that the scriptures used such language out of necessity and convenience, taking into account the nature of man, which is to arrive at truths through the senses and bodily images. Consequently, “symbolic language lies at the very core of sacred doctrine; it is the language God Himself uses to communicate with men in Sacred Scripture.”(31) The second consideration deals with the senses of scripture.(32) Aquinas makes three points: first, God is the author of scripture; consequently, everything in scripture is inspired by God. Second, the literal sense of scripture is what God and the human author intended by the words; this is the sole sense that can be used in theological argumentation. And third, only God can give to persons and events narrated a spiritual sense, which is allegorical, moral, and anagogical.(33) Here we have expressed the most fundamental intrinsic modality of sacred teaching. Since the scriptures are the “holy writings” of this doctrine, namely, sacra doctrina, their uniqueness imposes a basic characteristic on the whole of sacred teaching or Christian theology.


The foregoing brief analysis of what St. Thomas Aquinas meant by theology should make it quite clear that everything in the Summa Theologiae is, in a very important sense, theological. But that does not lead us to the conclusion that it contains no philosophy. Nor does it prohibit, as Russell and Heidegger seemed to have suggested, genuine philosophizing. Indeed, the point Aquinas conveys in his Exposition of Beothius on the Trinity regarding “natural desire” is quite germane: man is naturally orientated toward a supernatural destiny, and, accordingly, philosophy is naturally orientated toward a superphilosophical type of knowledge.(34) Such an orientation does not eliminate the philosophical enterprise; rather, as the notion of sacra doctrina outlined in this article also indicates, the philosophical enterprise is included within the formal object of theology and becomes, therefore, theological in its own right.

Nor need there be any difficulty when sacred teaching utilizes the methods of philosophy. In such cases-scholastic theology in the “best” sense of the phrase-the theologian makes use of human reason as a method of expositing the truth of faith, not proving it. Truth cannot contradict truth.

Such conclusions are critical to any discussion of the theme of faith and reason in the writings of Aquinas. Reason or philosophy can prove some of the truths which are proposed by the Christian faith, it can elucidate truth which cannot be proved, and it can defend the principles of the faith against detractors. At the same time, given the analysis of Thomas in the introductory question of the Summa, the subjects with which the philosopher is ultimately concerned are already proposed by sacred teaching. It is therefore natural that the two disciplines be allied.


1 Anton C. Pegis, Christian Philosophy and Intellectual Freedom (Milwaukee: Bruce Publishing Company, 1955), p.33f.

2 Bertrand Russell, A History of Western Philosophy (New York: Simon and Schuster, 1945), p.463.

3 Martin Heidegger, Holzwege (Frankfurt, 1950), p.132. For a summary of Heidegger’s attitude toward medieval philosophy see J.L. Mehta, The Philosophy of Martin Heidegger (New York: Harper and Row, 1971), pp. 154-155.

4 In large measure, the matrix for the present discussion is the position which I share with Pegis concerning the work of St. Thomas: he was “not a philoeophns, but a theologus philosophans, a philosophizing theologian, a man who worked as a theologian in his own philosophy”. See his “Who Reads Aquinas?”, Thought, XLII (Winter, 1967), pp.491-496.

5 Jacques Maritain, Science and Wisdom (London: Geoffrey Bles, Ltd., 1954), p.27.

6 Ibid., p.28.

7 Ibid.

8 Etienne Gilson, The Spirit of Thomism (New York: P.J. Kenedy and Sons, 1964), pp.14-18.

9 SCG, I, 1.

10 Ibid.

11 Ibid.

12 SCG, 1, 4.

13 S.T., I-I, q.1, a.1 (Marietti edition): Primo quidem quia homo ordinatur ad Deum sicut ad quendam finem qui comprehensionem rationis excedit, secundum illud Isiae 44,(4): ‘oculus non vidit Deum absque te, quae praeparasti diligentibus te.’ Finem autem oportet esse praecogniturn hominibus, qui suas intentiones et actiones debent ordinare in finem. Unde necessarium fuit homini ad salutem, quod ei nota fierent quaedam per revelationem divinam, quae rationem humanan excedunt.

14 Ibid.

15 Ibid., ad. 2.

16 S.T., I-I, q.1, a.7.

17 I am consciously avoiding the phrase, “holy teaching”, because of its connection with Victor White’s monograph, Holy Teaching: The Idea of Theology According to St. Thomas Aquinas (London: Blackfriars Publications, 1958). 1 find White’s emphasis on the kerygmatic or pastoral conception of theology which he believes is in Thomas (as belies his interpretation of incipientes) somewhat questionable.

18 These three emphases are actually a compressed outline of Garrigou-Lagrange’s division of the first question into five sections. See his De Deo Uno: Commentarium in Primam Partem S. Thomae (Paris, 1938), p.36ff. Garrigou-Lagrange agrees that the first article is not about scientia theologica but about sacra doctrina, which abstracts from “faith” and “theology”.

19 S.T., I-I, q.1, a.l.

20 It should be noted that Thomas is not demonstrating the necessity of a knowledge of divine truths for salvation; that is one of his premises. He argues from this necessity of a knowledge of divine truths to the necessity of their being made known through revelation. See G.F. Van Ackeren, Sacra Doctrina: The Subject of the First Question of the Summa Theologlae (Rome: Catholic Book Agency, 1952), pp.80-81.

21 S.T., I-I, q.1, a.2: Sed sciendum est quod duplex est scientiarum genus. Quaedam enim sunt quae procedunt ex principiis notis lumine naturali intellectus, sicut arithmetica, geometria, et hujusmodi; quaedam vero sunt quae procedunt ex principiis notis lumine superioris scientiae, sicut perspectiva procedit ex principiis notificatis per geometriam et musica ex principiis per arithmeticam notis.

22 Ibid.: Et hoc modo sacra doctrina est scientia, quia procedit ex principiis notis lumine superioris scientiae, quae scilicet est Dei et beatorum. Unde sicut musica credit principia sibi tradita ab arithmetico ita sacra doctrina credit principia revelata a Deo.

23 Etienne Gilson, Elements of Christian Philosophy (New York: New American Library, 1963), pp.30-31.

24 S.T., I-I, q.1, a.3, ad.2.

25 Ibid.: ut sic sacra doctrina sit velut quaedam impressio divinae scientiae, quae est una et simplex omnium. See also, J.F. Bonnefoy, “La theologie comme science et 1’explication de la foi selon saint Thomas d’Aquin”, Ephemerides theologicae lovanienses, XIV (1937), pp.421-426, and XV (1938), pp.491-516.

26 Gilson, Elements of Christian Philosophy, pp.37-45.

27 However, I would venture that for Thomas, as opposed to Bonaventure for example, sacred doctrine is more formally speculative because divine revelation tells man more of divine things than of human actions. I disagree with White’s argument that sacra doctrlna is wholly and supremely practical for Aquinas.

28 S.T., I-I, q.1, a.5. Any doubts about the principles of faith arise, according to Thomas, from the weakness of man’s intellect, not any deficiency in revelation. It might be observed that the confusion that seems to obtain on the relationship of philosophy to theology has no other cause than this often neglected fact.

29 Van Ackeren, Sacra Doctrina: The Subject of the First Question of the Summa Theologise, p.107.

30 S.T., 1-1,q.1, a.8. One of the better summaries of articles 8-10 is in James Weisheipl’s “The Meaning of `Sacra Doctrina’ “, The Thomlst, (January, 1974), pp.76-79. I have followed it closely.

31 Ibid., p.78.

32 S.T., I-I, q.1, a.10. M.D. Chenu argued that the logic of Thomas’ theory would eliminate this article from the consideration of sacra doctrina, but I disagree. See his La theologie comme science an 7fQII slecle (Paris: Vrin, 1943), p.125.

33 For a good treatment of the role of scripture in Thomistic theology see J. van der Ploeg, O.P., “The Place of Holy Scripture in the Theology of St. Thomas”, The Thomist, X (1947), pp.398-422.

34 In Boethlnm De Trinitate Expositio, ed. by B. Decker (Leiden, 1955).