Thomas Cajetan

Thomas Cajetan OP (/ˈkædʒətən/ KAJ-ə-tən; 20 February 1469 – 9 August 1534), also known as Gaetanus, commonly Tommaso de Vio or Thomas de Vio, was an Italian philosopher, theologian, the Master of the Order of Preachers 1508 to 1518, and cardinal from 1517 until his death. He was a leading theologian of his day who is now best known as the spokesman for Catholic opposition to the teachings of Martin Luther and the Protestant Reformation while he was the Pope's legate in Augsburg, and among Catholics for his extensive commentary on the Summa Theologiae of St. Thomas Aquinas.

He is not to be confused with his contemporary Saint Cajetan, the founder of the Theatines.

He was born in Gaeta, then part of the Kingdom of Naples, as Jacopo Vio. The name Tommaso was taken as his religious as a friar, while the surname Cajetan derives from his native city. At the age of fifteen, he entered the Dominican order and devoted himself to the study of the philosophy of St. Thomas Aquinas, becoming before the age of thirty a doctor of theology at Padua, and subsequently professor of metaphysics. A public disputation at Ferrara (1494) with Pico della Mirandola made his reputation as a theologian.

He became general procurator in 1507 and general of the Dominicans a year later in 1508.

In 1511 a group of dissident cardinals called the Conciliabulum of Pisa (1511–1512) against Pope Julius II, who had ignored the electoral capitulations he had accepted before being elected. Cajetan displayed vigorous support for the papacy in a series of publications. These were condemned by the Sorbonne and publicly burnt by order of King Louis XII.

At the Fifth Lateran Council (1512–17) which Pope Julius II set up in opposition to that of Pisa, De Vio played the leading role. During the second session of the council, in which he gave the opening oration, he obtained the approval of a decree recognizing the superiority of papal authority to that of councils.

Cajetan composed in defence of his position the Tractatus de Comparatione auctoritatis Papæ et conciliorum ad invicem. Jacques Almain answered this work, and Cajetan replied in his Apologia. Cajetan refused to accept Almain's argument that the Church's polity had to be similar to a lay regime, complete with limits on the ruler.

For his support of papal rights, Cajetan was made Bishop of Gaeta, and in 1517 would be made a cardinal and archbishop of Palermo by Pope Leo X.