Theology as Science: Reading Aquinas: Summa Theologiae I, Q. 1, Art. 2-4

In the first post in this series, we read through the Prologue and the first article of St. Thomas Aquinas’s magnificent Summa Theologiae, focusing on the relationship between and divine revelation. This post will focus on the relationship between theology and science.

In Part I, the second article of Question 1 begins:

“Whether Sacred Doctrine Is a Science?

Objection 1: It seems that sacred doctrine is not a science. For every science proceeds from self-evident principles. But sacred doctrine proceeds from articles of faith which are not self-evident, since their truth is not admitted by all: “For all men have not faith” (2 Thess. 3:2). Therefore sacred doctrine is not a science” (ST I, Q. 1, Art. 2) [1].

“Science” here is translated from scientia, meaning a “branch of knowledge” [2], used in the classical sense as opposed to the modern, limited sense referring only to the technical definition. The objection here is that science, by its very definition, “proceeds from self-evident principles”, meaning that it is based upon “premises the truth of which can be recognized by us while using the rational faculties with which we are endowed” [3]. In other words, as we saw from Article 1, reason alone will never take us to some of the doctrinal truths contained within Christian theology. Left to our own devices, even the most brilliant of human intellectuals never would have discovered that there is a triune God or some other of “the hidden things” of God [4]. These things had to be revealed to us directly by God in order for us to know them. But that is not science. Science, in the sense being used here, going back to Aristotle’s own description, starts from what is firmly held to be true via the senses and reasons to underlying causes/principles that explain those facts. But sacra doctrina does not start from what is known to be true via the senses, so it cannot be a science.

The next objection:

” Obj. 2: Further, no science deals with individual facts. But this sacred science treats of individual facts, such as the deeds of Abraham, Isaac and Jacob and such like. Therefore sacred doctrine is not a science (ST I, Q. 1, Art. 2) [5].

This objection might seem a bit strange, but I think what it is getting at is the fact that science is concerned with a more general body of knowledge and broader, underlying principles rather than the individual facts themselves which the principles are induced to explain. Or, perhaps, sciences deal with causal/explanatory principles, while relaying of particular events such as the lives of Abraham, Isaac, and Jacob are just descriptive accounts.

The beginning of Aquinas’s response then appeals to the great St. Augustine:

On the contrary, Augustine says (De Trin. xiv, 1) ‘to this science alone belongs that whereby saving faith is begotten, nourished, protected and strengthened.’ But this can be said of no science except sacred doctrine. Therefore sacred doctrine is a science” (ST I, Q. 1, Art. 2) [6].

Given, then, that Augustine has labelled these things which are only explicable via sacred doctrine as “science”, it must be the case that sacred doctrine is indeed a science (given, of course, that we already trust St. Augustine, but that is a whole other issue).

His response continues:

I answer that, Sacred doctrine is a science. We must bear in mind that there are two kinds of sciences. There are some which proceed from a principle known by the natural light of intelligence, such as arithmetic and geometry and the like. There are some which proceed from principles known by the light of a higher science: thus the science of perspective proceeds from principles established by geometry, and music from principles established by arithmetic. So it is that sacred doctrine is a science because it proceeds from principles established by the light of a higher science, namely, the science of God and the blessed. Hence, just as the musician accepts on authority the principles taught him by the mathematician, so sacred science is established on principles revealed by God” (ST I, Q. 1, Art. 2) [7].

So Aquinas’s answer is that there are, in fact, two kinds of science. The first does indeed begin with self-evident principles, such as mathematical truths. But there are also sciences which, while not themselves consisting of necessarily “self-evident” principles, nonetheless are built upon that more foundational science. We might think, to take a more modern example, of architecture as a type of science that is built upon the “higher science” of geometry. These latter types of sciences must assume from the start that the higher science is true in order to proceed. To take another more modern example, we might say that “physics” is a higher science, while chemistry is a science which is built upon it. Chemists operate their own science on the assumption that physics is true. So, St. Thomas says, sacred doctrine is like this. The relevant higher science is just “the science of God and the blessed”, or, in other words, the perfect knowledge that God and those in His presence automatically possess (for God, of course, knows His own essence, and so do those in His presence). This knowledge is then revealed to us directly by God, and, in our constructing theological systems to adequately understand it, we must take its truthfulness as a given, on authority. Sacred science, then, is the science of coming to understand and reach conclusions about that knowledge which has been revealed to us. While many modernists might take issue with the whole “authority” thing, especially of a divine sort, this is irrelevant to the present discussion (which assumes that divine revelation really has been given to us). The point being made here is just that what science truly is is to “rightly deduce conclusions that follow from what is already given or known” [8]. All sciences, not just theology, take certain facts as given, foundational knowledge that cannot be disputed in order to function. Modern science, for example, takes the existence of an external, physical reality as a given assumption, without being able to actually affirm this by its own methods. But even in the broader sense of just a general body of knowledge, sciences just have to start/be built upon a certain foundational knowledge. For some sciences, this foundational knowledge is “self-evident” to the senses or to the natural intelligence. But, argues Aquinas, this is not a necessary requirement for all sciences. As long as that foundational knowledge is there and is firmly established, then its source does not levy discriminatory treatment. And divinely revealed knowledge surely meats this requirement, even if it must be accepted on authority.

Aquinas then answers the specific objections:

“Reply Obj. 1: The principles of any science are either in themselves self-evident, or reducible to the conclusions of a higher science; and such, as we have said, are the principles of sacred doctrine (ST I, Q. 1, Art. 2) [9].

This just repeats the distinction in types of sciences that has just been discussed.

“Reply Obj. 2: Individual facts are treated of in sacred doctrine, not because it is concerned with them principally, but they are introduced rather both as examples to be followed in our lives (as in moral sciences) and in order to establish the authority of those men through whom the divine revelation, on which this sacred scripture or doctrine is based, has come down to us” (ST I, Q. 1, Art. 2) [10].

So sacred doctrine is not principally concerned with individual facts, but the individual facts are important in two senses: 1) as examples, as a teacher in moral philosophy might give practical applications of the theories he is delivering, and 2) as a sort of “ethos” to convince us of the authority of the vessels of revelation. For example, being told through scripture about the life of Moses as a whole gives us a better context and basis for trusting his authority in delivering the divinely revealed Law and commandments.

That is the conclusion of Article 2. But, before moving on, a few more thoughts: Aquinas takes it that certain aspects of sacred doctrine must be accepted on faith. As we discussed in the previous post, however, faith here is not something opposed to or inferior to reason; in fact it is higher than reason, because its object is something transcends the ability of the human mind to fully grasp. This is also not a blind faith, because it is not meant to be believed without reason. Reason leads us to believe that certain things are true, such as that God exists, that Jesus claimed to be the divine, unique Son of God and was then resurrected from the dead, that Christianity is true, that Scripture is inspired, etc. If these things can be established by reason, it is then that we accept on faith the sacred doctrines which arise from them. We cannot know, for instance, by reason that God is a trinity. But if we can come to know that Christianity is in essence true, then we have firm grounds for accepting and believing the doctrine of the trinity. In a sense, then, philosophy leads and builds up to theology.

We will now turn to Article 3:

“Whether Sacred Doctrine is One Science?

Objection 1: It seems that sacred doctrine is not one science; for according to the Philosopher (Poster. i) ‘that science is one which treats only of one class of subjects.’ But the creator and the creature, both of whom are treated of in sacred doctrine, cannot be grouped together under one class of subjects. Therefore sacred doctrine is not one science.

Obj. 2: Further, in sacred doctrine we treat of angels, corporeal creatures and human morality. But these belong to separate philosophical sciences. Therefore sacred doctrine cannot be one science” (ST I, Q. 1, Art. 3) [11].

Science, according to the Philosopher (aka Aristotle), is one if it deals with one class of things. So biology is “one” science in that it focuses on the class of living organisms, astronomy in that it focuses on celestial objects, etc. But, the objection points out, sacred doctrine deals with lots of different things, and lots of different types of things, including both God and man, which are completely and totally different. So it cannot be just one science with one object or class of objects of study. In addition to this, many of the items treated in sacred doctrine are already objects of other sciences. Anthropology, for example, deals with humanity; biology deals with corporeal creatures; ethics deals with human morality, etc. Since all these things already belong to different sciences, and sacred doctrine involves all of them, sacred doctrine must not be its own, individual science.

Aquinas answers:

On the contrary, Holy Scripture speaks of it as one science: ‘Wisdom gave him the knowledge [scientiam] of holy things’ (Wis. 10:10).

I answer that, Sacred doctrine is one science. The unity of a faculty or habit is to be gauged by its object, not indeed, in its material aspect, but as regards the precise formality under which it is an object. For example, man, ass, stone agree in the one precise formality of being colored; and color is the formal object of sight. Therefore, because Sacred Scripture considers things precisely under the formality of being divinely revealed, whatever has been divinely revealed possesses the one precise formality of the object of this science; and therefore is included under sacred doctrine as under one science” (ST I, Q. 1, Art. 3) [12].

In short, even sciences with one formal object can have many different subjects; biology, for example, deals with mammals as well as reptiles, astronomy deals with stars as well as planets, etc. To use Aristotle’s framework, every science studies being/existence/reality in a particular manner and context. Biology studies being qua life, physics studies being qua physical reality, and metaphysics, the deepest and broadest of all sciences, studies being qua being itself. Thus sacred doctrine is a science that studies being qua divinely revealed truth. Everything which has been divinely revealed by God to man is the object of this sacred science.

“Reply Obj. 1: Sacred doctrine does not treat of God and creatures equally, but of God primarily, and of creatures only so far as they are referable to God as their beginnings or end. Hence the unity of this science is not impaired.

Reply Obj. 2: Nothing prevents inferior faculties or habits from being differentiated by something which falls under a higher faculty or habit as well; because the higher faculty or habit regards the object in its more universal formality, as the object of the common sense is whatever affects the senses, including, therefore, whatever is visible or audible. Hence the common sense, although one faculty, extends to all the objects of the five senses. Similarly, objects which are the subject-matter of different philosophical sciences can yet be treated of by this one single sacred science under one aspect precisely so far as they can be included in revelation. So that in this way, sacred doctrine bears, as it were, the stamp of the divine science which is one and simple, yet extends to everything” (ST I, Q. 1, Art. 3) [13].

To the objection that sacred doctrine deals with both God and creatures, which are in completely different categories of being, and thus does not have only one object, Aquinas responds that actually, sacred doctrine is primarily concerned with God, and with creatures only with respect to the fact that they are creations of God and directed towards God.

To the objection that sacred doctrine is concerned with subjects which are elsewhere considered in separate, independent sciences, and thus cannot be one science on its own, Aquinas gives a more lengthy response. He uses the example of common sense related to the five senses. Each of the five senses has its own medium of perception. But common sense uses all five of the senses as its own medium. So whatever is perceived through one of the senses is also perceived by common sense as well. This is just to make the point that objects of independent sciences can still fit under a higher science. So even though humans and animals and the physical universe all have their own, independent sciences which study them, they can all, insofar as they relate to divine revelation, fit under the higher science of sacred doctrine. This is captured in that beautiful, poetic last line: “In this way, sacred doctrine bears, as it were, the stamp of the divine science which is one and simple, and yet extends to everything.”

Article 4 asks “whether sacred doctrine is a practical science?” [14], and I will just very briefly go over it in conclusion. The objects differentiate between “speculative” and “practical sciences.” The former is just concerned with knowledge about things; the latter is concerned with action, and specifically human action. The obvious example of a practical science is moral philosophy, which considers what we do and how we live. Aquinas’s answer is that sacred doctrine is in some ways both speculative and practical, because it does indeed concern human action, “inasmuch as man is ordained by [divine things] to the perfect knowledge of God in which consists eternal bliss” [15]. So although it is practical, sacred science is primarily and fundamentally speculative, because it is the knowledge that ordains action.

In the next post, we will turn to Article 5.



[1]. Aquinas, Thomas. Summa Theologica. 1265-1274. Trans. Fathers of the English Dominican Province. Coyote Canyon Press, 2010. ebook. I, Q. 1, Art. 2.

[2].See Davies, Brian. Thomas Aquinas’s Summa Theologiae: A Guide & Commentary. New York: Oxford University Press, 2014. Print, 19.

[3]. Ibid., 20.

[4]. Ibid., 19.

[5]. Aquinas, Thomas. Summa Theologica. 1265-1274. Trans. Fathers of the English Dominican Province. Coyote Canyon Press, 2010. ebook. I, Q. 1, Art. 2.

[6]. Ibid.

[7]. Ibid.

[8]. Davies, Brian. Thomas Aquinas’s Summa Theologiae: A Guide & Commentary. New York: Oxford University Press, 2014. Print, 20.

[9]. Aquinas, Thomas. Summa Theologica. 1265-1274. Trans. Fathers of the English Dominican Province. Coyote Canyon Press, 2010. ebook. I, Q. 1, Art. 2.

[10]. Ibid.

[11]. Ibid., Art. 3.

[12]. Ibid.

[13]. Ibid.

[14]. Ibid., Art. 4.

[15]. Ibid.

Cover Image: Michelangelo [Public domain], via Wikimedia Commons,



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