Tommaso de Vio (d. 1534), known as Cajetan, distinguished himself in several fields of philosophy and theology before becoming Master General of the Dominican Order and a cardinal. Hochschild's book looks at one important philosophical contribution, Cajetan's theory of analogy. The focus of the book is on the text De nominum analogia [DNA], completed in 1498. Written while the author was studying theology in Padua, DNA is one of a series of writings from his early career. The tract follows close upon the completion of commentaries on the De ente et essentia of Thomas Aquinas (1495) and Aristotle's Categories (1498). Hochschild is careful to specify that Cajetan was writing from the viewpoint of logic and not of metaphysics, although he was aware that his theory of analogy had wider implications. Hochschild also makes the important point that Cajetan was not simply explicating the works of Thomas Aquinas. DNA was written to answer an argument of Duns Scotus that there was no middle ground between a “univocal” term (always used in the same sense because of a shared concept) and an “equivocal” one (used in different senses because of differing concepts that shared a common word). Consequently the work addressed an issue about which Aquinas had not written in a systematic manner. Moreover, DNA contains more references to the works of Aristotle than to those of the Angelic Doctor. (Cajetan also used the works of Averroës in writing DNA.)

Hochschild structures his book as a review of the literature on Cajetan's theory of analogy, much of it critical, and a reply that defends his subject's teaching. The author is particularly careful to answer critics who have treated DNA as straying from the strictest form of Thomism. The reply to these critics includes a detailed discussion, chapter by chapter, of DNA. The style is dense, but the diagrams the author provides help clarify technical issues. Hochschild also examines the three types of analogy Cajetan listed. Analogy based on inequality or attribution, Cajetan argued, was less perfect than analogy of proportionality. Analogy of inequality was a form of univocation, since the concepts are the same naturally (simpliciter), although differing after a fashion. Analogy of attribution combines concepts naturally different, and therefore follows the rules governing equivocation. Only proportionality, in Cajetan's opinion, was a true mean between the univocal and the equivocal. The others were capable of being read too loosely (abusive), weakening their utility in the reasoning process. Analogy of proportion, consequently, is treated as more important and is described by Cajetan in greater depth. This exposition is rooted not just in Cajetan's reading of Aristotle's Organon, his collected works on logic; it requires an understanding of names as dependent on their contexts in sentences. This placed Cajetan at odds with some of his contemporaries, who regarded words as having properties independent of their contexts in sentences.

Proportion is treated by Cajetan as based on sameness in linguistic usage. Different natures are described as having “sameness” in proportion as the mind conceives that relationship, although they are materially different. Cajetan was well aware that proportional unity had a respectable Aristotelian pedigree as a form of sameness “alongside of numeric, specific, and generic unity” (125). They have a similarity in conception, although not in the things themselves that are being compared. An example of this is wisdom. God and a wise human being both have wisdom, but not in the same exact way. God's wisdom is different, transcendent; and human wisdom only can resemble it. Cajetan does warn against misuse of the analogy. Two humans can be called wise, but this is in a univocal, not an analogous sense of the word. Moreover, Cajetan warns against treating literary metaphors as logical analogies.

Hochschild's contribution to the debate over Cajetan's doctrine of analogy is likely to provoke replies from a philosophical viewpoint. From a historical viewpoint, this book makes it clear that Cajetan was not simply a commentator on the works of Thomas Aquinas. He was capable of addressing problems, like analogy, not addressed in depth by the Angelic Doctor; and he was capable of going back to Aristotle in order to answer Scotus on this particular topic. Hoschschild's book presents us with a more interesting and original philosopher in Cajetan than he would seem if we limited ourselves to his fidelity to the Angelic Doctor or to the Thomism of his own day.