Brock, Stephen L. The Light That Binds: A Study in Thomas Aquinas’s Metaphysics of Natural Law. Eugene, OR: Pickwick Publications, 2020. IBSN: 978-1-5326-4731-4; List price: $35.00 paperback.

Stephen L. Brock’s The Light That Binds is an excellent treatment of St. Thomas Aquinas’s natural law teaching in the Summa theologiae. The exposition and argument present a cogent and insightful tour of the theological and metaphysical architecture of the legal transept, as it were, of the cathedral that is Aquinas’s Summa, all while engaging the views of a variety of contemporary scholars. In what follows, I consider the book overall, note some high points of its chapters, and offer some thoughts for future readers of the book.

The first chapter elaborates the overall architecture of Brock’s argument, laying down four essential positions concerning the properly legal character of the natural law. The key question, in this regard, is as follows: Does understanding the essence of natural law require reference to God’s eternal law, or not? If the answer is no, then how is the natural law fully “law” in the Thomistic sense of that term? If the answer is yes, then how is the natural law, qua law, also fully “natural”? The book sets out to defend Brock’s answer to these questions. 

The second chapter considers the relationship between the natural law and the eternal law, and answers the key question affirmatively. How, then, is the natural law, as law, also fully natural? Must we somehow be notified of its legal character in the way we are of human laws in order to recognize it as law? Brock defends a negative answer to this question in the third chapter, and so, in the fourth and fifth chapters, must explain how, according to St. Thomas, we do in fact come to know the natural law as law. Having argued that such knowledge is not in certain key ways dependent upon our knowledge of natural inclinations (see below), Brock explores the obligatory force of the natural law in the sixth chapter, and the various ways in which it is natural in the seventh, wherein he also concludes with responses to the other positions taken with regard to the key question.

The first chapter is devoted to laying out the positions of these interlocutors. They are as follows (see 30–31).

1. The natural law can be adequately treated without reference to God’s eternal law, and so it is not fully law (Lottin, Grisez, Finnis, Adler, Kluxen).

2. The natural law can be adequately treated without reference to God’s eternal law, and yet it is still fully law (Donagan, Copleston, Stevens, O’Donoghue).

3. The natural law cannot be adequately treated without reference to God’s eternal law, and, while fully law, is not fully natural (Fortin, Jaffa).

4. The natural law cannot be adequately treated without reference to God’s eternal law, and is both fully law and fully natural.

   4a. The required inferences for fully legal and natural status, i.e., knowing its divine origin, are within the reach of human reason, and this results in a satisfactory overall account (Suárez).

   4b. The required knowledge of divine origin is required to understand the natural law as law, but not required in order for it to function as law (Farrell, Geach, Anscombe).

Brock’s own position falls within this last sub-category:

Thomas’s natural law is a full-fledged law, and it is so inasmuch as it is promulgated to man by the divine lawgiver through the natural light of reason. ... [F]or Aquinas, its promulgation is completed in the natural understanding of the truth of its precepts, even before their having been instituted and promulgated by God is itself understood. Compliance with its precepts will indeed lead (at least with the help of grace) toward that understanding, but the force of law that is proper to the precepts does not absolutely suppose or depend upon it. (239)

The defense of his view is begun in Chapter 2, with Brock’s affirmation that properly understanding the natural law requires reference to God’s eternal law. Historically, Brock shows how Aquinas’s treatment of the natural law departs from the order of consideration found in the contemporary work Summa fratris Alexandri, both in his focus on the general nature of law as a separate topic and by linking natural law to eternal law and distinguishing it from synderesis. Brock then embarks on a close reading of ST, Ia-IIae, q. 90, especially aa. 1–2, defending the element of promulgation as the species-making difference of the types of law and arguing that “participation of the eternal law in the rational creature” (58) is the strict, formal definition of natural law, to which others, such as “first principles of practical reason” are secondary or material (60). Concerns that this treatment ignores the importance of the other elements of the definition of law—in particular, the common good—are allayed in the next chapter.

Chapter 3 develops Brock’s views regarding “the way in which the precepts of natural law can be seen as effects of the divine will and the divine command ordering all things toward the divine common good,” a connection which “may be the book’s philosophically most important moment” (xiv). The chapter argues that assenting to the obligatory force of the natural law is possible without explicit “advertence to divine authority” (63). This is because the eternal law is not a sort of divine positive law which extrinsically enjoins the natural law, but it is rather the source of the intrinsic force of natural-law obligation arising from the very ratio of the good. How does this assist us in seeing that the natural law is fully legal despite lacking promulgation in the manner of human positive laws? The reason lies in defusing certain objections from Suarez and a version of the Euthyphro problem. This is done in Brock’s illuminating discussion of the relationship between God’s will, the eternal law, and the common good of the universe. God is the extrinsic common good of the universe, whose intrinsic good is the good of its order. God’s creative act is also a legislative act by which he constitutes “the community of the universe, all the way down to the very natures or essence of its members,” and this itself “is an ‘ordination of reason, for the common good, by the one who has care of the community’” (94). The eternal law constitutes the very goods and evils of created natures. Thus, “natural law does have its force from God’s command, but not solely in light of its relation to that command; for the command itself gives it an intrinsic force. Its force is its truth” (100). It is a law promulgated through human nature itself.

How exactly, then, do we know the natural law? Is it through a speculative knowledge of the natural inclinations arising from human nature? Chapters 4 and 5—which, he notes, were originally one chapter in the dissertation from which the book is developed—articulate Brock’s patchwork of agreements and disagreements with various interpreters of Aquinas’s natural inclination text, namely: “all the things toward which man has natural inclination, reason naturally apprehends as good, and consequently as things to be pursued by action, and their contraries as bad and to be avoided” (111; see ST, Ia-IIae, q. 94, a. 2, c.). Noting that the text is frequently read as saying that human goods are known by way of or in function of knowing the natural inclinations of human nature, Brock defends the thesis that we must first know the good (that which “reason naturally apprehends as good”) before knowing the natural inclinations ordered to that good. However, unlike alternative defenses of this sort of priority in our knowledge—such as Grisez and Finnis (who defend the self-evident immediacy of practical reason’s grasp of the good), or Maritain (who defends a connatural knowledge of the good)—Brock develops certain insights from Fr. Lawrence Dewan, O.P., and argues that the inclinations in question are not pre-rational but must be taken precisely as rational, that is, what reason naturally apprehends to be good (127–28ff). The good bears within itself its own intelligibility as apprehended by reason.

For all that, however, this still involves a basic grasp of human nature, as Chapter 5 articulates. That is, for reason to grasp the ratio boni it does not suffice to understand the goods of the sense appetites; rather, we must understand our own order to being and truth qua rational in order to grasp the meaning of the good (144–45). Here, Brock relies upon ST, Ia, q. 16, a. 4, ad 2:

First, intellect apprehends just a being (ipsum ens); second, it apprehends itself understanding (apprehendit se intelligere) a being; and third, it apprehends itself desiring (apprehendit se appetere) a being. Whence, although the good is in things, there comes first the ratio of a being; second the ratio of a true [which is in the mind]; and third the ratio of a good. (Brock’s translation)

That is, the intellect—shorthand for this man, thinking with his intellect—grasps the notion of the good when it sees how truth is a desirable perfection of what is due the intellect given its nature as a power. It is in this way that the intellect can preconceive such a good as fitting for itself and thus desire it through intellectual appetite, the will (145). In other words, our grasp of the good for us—as vague as it may be at first—already includes a grasp of what perfects our nature. When this receives proper theoretical development, it permits us t avoids the problems that so entangle Hume and bedevil the new natural law reception of the naturalistic fallacy (148–50). Nevertheless, Brock argues at length, this ontological and epistemological causal matrix for our grasp of the good is not incompatible with a common-sense grasp of good and evil. That is, one does not require a philosophical grasp of human nature and a speculative theory of the good (158ff; perhaps this is where Maritain’s connatural knowledge could be considered in comparison), and this broadly-speaking speculative grasp of the good is prior to a practical understanding of the human good, just as nature is prior to art’s imitation of it (167ff).

Chapter 6 concludes the main work of the book by investigating how the natural law is obligatory and binding. The final chapter (Chapter 7) then draws out various features of natural law precisely as natural. The former chapter argues that the obligation of natural law is the sort of intrinsic obligation applicable to law, one that indicates to rational agents the necessity of compliance “for the sake of something more basic than objects of merit: attaining goodness or rectitude” (196–97). The binding force of the natural law, its sanction, is the remorse of conscience, which Brock discusses at length (197ff). The latter, concluding chapter of the book discusses the various duties of the natural law with particular reference to the natural law content of the Old Law and what duties belong to the natural law absolutely considered. To what degree does the natural law require instruction by the wise or through revelation? How do precepts of the First and Second Tables of the Law interact with the need for divine grace such that they might be fully known? How does this affect the culpability of those individuals of the fallen human race who lack such grace or wise instruction? These pages are especially illuminating in regard to the role of conscience and the character of one’s own knowledge of the objective natural law, for everything is received in the mode of the receiver. The chapter closes with a review of the various opposing positions that Brock introduced in the first chapter and had been engaging with throughout.

The Light that Binds is an erudite work of Thomistic scholarship and will serve those with sufficient familiarity of Aquinas and his sources as an insightful philosophical guide to a deeper understanding of the Angelic Doctor’s natural law teaching. It is especially helpful in providing responses to aspects of competing schools of interpretation. Brock does note and comment on literature in the field that postdates the work’s previous life as a doctoral dissertation, and there are no noticeable or culpable oversights in this regard. Still, eager graduate students of Thomistic philosophy would do well to compare and contrast the details of Brock’s articulation with, for instance Steven Jensen’s Knowing the Natural Law.

Where Brock’s book is best is in its attention to the theological and sapiential nature of its source material, the Summa Theologiae, which is read and interpreted as it was meant to be: as a whole, with attention to the synoptic architectural ratio of St. Thomas’s metaphysical and theological vision. This is especially the case when it comes to Brock’s emphasis upon how natural law is integrated into the character of the common good of the universe as the total object of God’s creative act. His crucial defense of a first principle of such magnitude—the primacy of the universe’s common good as constitutive of the ratio boni for a the universe of beings who are law-governed—is the first among many reasons why Fr. Brock’s The Light that Binds deserves a wide readership:

To put it in Dewan’s terms, the “goodness of being” is not a principle of God’s institution of the order of the eternal law. It is an effect of that institution. God’s will for His own good is the very source, the agent, of the whole order of being, cause of the nature of being and of its attributes, which include its goodness. There is no end for the sake of which He wills it, other than His own good. His good, alone, is what “universal being and good” are for the sake of. It is in this sense that our natural apprehension of universal being and good gives us an immediate order to Him. And this is why the practical implications of this apprehension constitute a full-fledged law, and one that does not “fall short” of the eternal law as human law does. It is a divine law, one that of itself leads toward God’s goodness, and it is not “something diverse” from the eternal law, but simply a participation in it. God as creator and Father of lights and God as lawgiver are one and the same. This is why the light of reason is, intrinsically, a light that binds. (248–49)