Cardinal Cajetan, baptized Giacomo de Vio, is best known for his interview of Luther at Augsburg in 1518, but he was also a prolific theologian in his own right who authored more than 150 works and would produce an influential—and controversial—interpretation of Thomas Aquinas. Born in Gaeta, Italy, on 20 February 1469, he entered the Dominican order in 1484 and was given the name Thomas (Tomasso). He later studied philosophy at Naples, earning his bachelor’s in 1492. It was there that he first took the Latinized version of his hometown as a last name—Caietanus. He proceeded to study theology at Bologna and to lecture on Lombard’s Sentences at Padua, where he was awarded the master of sacred theology for his success in debate against the famed humanist, Pico della Mirandola, during a 1494 meeting of the Dominican order in Ferrara. He thereafter took up lecturing on Aquinas’s Summa Theologia at Pavia from 1497 to 1499. His reputation grew for his forceful defense of Aquinas against the followers of John Duns Scotus, who rejected the univocity of being, and the Averroists, who posited a two-source theory of truth.
Cajetan eventually moved to Rome, where he would serve in numerous capacities the remainder of his life. From 1501 to 1508, he lectured at the Sapienza University and served as procurator general for the Dominicans, functioning as a liaison between his order and the Roman curia. In 1508, he was appointed vicar-general of the Dominican order. During this period, he was active both administratively and theologically. He published an important 1509 commentary on the Aristotle treatise De anima in which he rejected the Averroist view that the immortality of the soul could only be proven by revelation rather than inferred from reason—the latter view being condemned at the Fifth Lateran Council (1512–17). He also played an important role in the convocation of Lateran V. When several cardinals sought to convene a council independent of Roman approval at Pisa in 1511, Cajetan appealed to Pope Julius II to convoke a legitimate council under papal authority. To this end, he composed a treatise against councils in support of papal authority that same year (De comparatione auctoritatis papae et concilii). As vicar-general, he also sent a Dominican contingent to the New World to inspect the Spanish colonization, eventually criticizing the conquest based on the reports brought back to him.
More significantly, these years saw Cajetan bring near to completion his massive commentary on Aquinas’s Summa, published between 1507 and 1520. What marked his interpretation of Aquinas was how closely he saw the Angelic Doctor as a thoroughgoing Aristotelian. As he had earlier in his career, Cajetan countered the arguments of Scottus against the univocity of being and the Averroists concerning the two-source theory of truth by emphasizing the analogy of being (analogia entis), or the belief that all humans have access to certain truths about God from their natural constitution, though not truths that are dependent upon revelation. This position, which ultimately came to draw an opposition between reason and revelation, would influence centuries of Thomistic thought. Two popes, Pius V (1570) and Leo XIII (1882), deemed it an authoritative interpretation of Aquinas and published the Summa with Cajetan’s commentary appended to it.
At the outset of the Reformation, however, Cajetan would take a formative role in the controversies after being named cardinal of St. Sixtus in Rome on 6 July 1517. He was initially appointed archbishop of Palermo, but resigned due to opposition the next year before receiving his native see of Gaeta on 14 March 1519. One of the first tasks of his cardinalate was to act as papal legate to Germany in order to rouse support for a crusade against the Turk and influence the election of Charles V as Holy Roman Emperor and successor to his father, Maximillian. This brought Cajetan to Augsburg for the diet of 1518, where he would have a fateful interview with Martin Luther in the home of the prominent Fugger bankers in October of that same year. Rome had initiated an investigation of Luther’s teachings on the basis of complaints brought forward by Albrecht of Mainz, to whom Luther had sent a draft of his controversial 95 Theses contesting indulgences. A towering intellect in his own right, Cajetan was commanded by Rome not to engage Luther, but instead to force him to recant. The cardinal could not resist the debate, however, and the result was three days of increasing tension between him and Luther as they argued over indulgences, Aquinas, canon law, and church authority.
The debate with Protestants would dominate Cajetan’s tenure as cardinal. He wrote numerous treatises against Protestant doctrines, in particular addressing Roman primacy (1521), the presence of Christ in the Eucharist (1525), the sacrifice of Mass (1531), and the role of faith and works in justification (1532). Despite their disagreements, Cajetan would urge continued theological dialogue with his opponents and even propose to Pope Clement VII in 1530 that Rome permit certain concessions to them in order to resolve the conflict, chiefly allowing clerical marriage and communion in both kinds. Other measures reflected his concern with reform. In 1519, he moved to resolve ambiguities in the theology of indulgences, such as Johannes Tetzel’s claim that the remission of sins did not require contrition of the heart on the part of the penitent purchasing an indulgence. In 1526, he composed a manual for confessors (Summula peccatorum) that placed confession in a more pastoral and theological light. In his capacity as a cardinal, he would also participate in the 1522 conclave that elected Adrian VI and visit Hungary, Poland, and Bohemia as legate in 1523 to gather support for a crusade.
Cajetan’s final years would be taken up by his interest in biblical interpretation. Between 1527 and 1534, he wrote numerous commentaries on Scripture, including a translation of the Psalms from Hebrew rather than the authorized Latin Vulgate. Though no humanist himself, the cardinal sympathized with the academic rigor and exegetical interests of the Renaissance humanists. He took many of their critical positions on Scripture, most notably suggesting that the Vulgate was an inferior text. Some of these views were criticized by his contemporaries and even censured by faculty members at the Sorbonne. Nonetheless, he was still a favorite to be elected pope after the death of Clement VII in 1534, but he grew ill and died himself on 10 August 1534. He was buried at the entrance of the Dominican church in Santa Maria sopra Minerva.