Thomas Aquinas’s “Summa contra Gentiles”: A Guide and Commentary by Brian Davies (review)

In this Guide, Brian Davies aims to write a book that is “introductory, if also comprehensive.” In this, he has succeeded marvelously. Of all the books on Thomas that seek to be both expository and philosophical, this is among the most readable. It is grounded in a careful reading of Thomas’s own text, yet it brings to bear the most important debates in contemporary philosophy of religion as well as the best of contemporary philosophical writing on Aquinas. It moves with ease between exposition of the text and the raising of probing questions. It also provides illustrative examples in portions of the text where they are most useful, for example, in the notoriously forbidding argument from motion. This is the work of a masterful scholar and teacher who has spent years thinking deeply about the texts of Aquinas.

Before turning to a lengthy and detailed exposition of the text itself, Davies supplies, in an opening chapter, background on Thomas’s life, work, and the setting of the Summa contra gentiles, a work whose purpose and structure have puzzled commentators for centuries. Davies notes that the structure and style of the Summa contra gentiles are distinct among Thomas’s texts. It is not a commentary, although it contains passages in which Thomas strives to show that his interpretation conforms to the text of Aristotle, nor is it organized according to the disputed-question model, although the listing of objections and responses occurs at important points in the text. The order of proceeding is quite different from that in the later Summa theologiae, in which Thomas adopts the method of theological scientia throughout and makes only a brief and passing reference to the philosophical sciences. By contrast, in the Summa contra gentiles he begins by dividing his treatment according to the “twofold mode of truth in what we confess about divine things,” with the first three books being devoted to that portion of divine truth accessible to reason, and the fourth to the segment that exceeds reason’s capacity. Davies speaks of the first three books as an “extended essay in natural theology” in which reason operates “without dependence on purportedly divine revelation” (7, 15). Like almost everyone now writing on the Summa contra gentiles, Davies dismisses the longstanding tradition that envisioned this work as Thomas’s response to the request from Dominican superiors for a book able to be deployed by Dominican missionaries working in Spain and useful in countering Islam.

Davies ends up calling it a “somewhat apologetic work” with three main purposes: “to reflect at length concerning what reason can tell us about God . . . to note ways in which what reason tells us about God harmonizes with what revelation teaches, and . . . to defend the articles of faith against charges of irrationality” (15, 13). That description works reasonably well, although it leaves out some of the peculiar structural features of the work, features that bear upon how we ought to understand Thomas’s own self-understanding: that is, how he understood his task in bringing together the two great sources of wisdom, philosophy and theology.

I mentioned above that Davies not only provides a clear exposition of the arguments with consideration of some of the puzzles in the arguments themselves, but that he also takes up relevant contemporary literature. Especially helpful is his use of the writings of Peter Geach and Herbert McCabe, members of what might be called the Wittgensteinian school of Thomism, distinguished by its care with language—with its logical structure, of course, but especially with the grammatical subtlety of ordinary language. For example, in his consideration of the objection that natural theology should be avoided altogether, Davies examines a set of objections: that it offends against piety; that the very notion of God is incoherent (Hume); and that God is...