I have sometimes come across the name of Fr. Cantoni in critical writings against SSPX, and wondered what his story is. Here is some biographical information about him, written by Roberto di Mattei, that appeared today on Rorate.
I know Fr. Cantoni just as well as I know Mons. Gherardini, having had contact with both of them since the beginning of the 1970s. At that time I was assistant to Augusto Del Noce, who disclosed to me that he thought Mons. Gherardini the best living Italian theologian. Piero Cantoni, who was born in Piacenza in 1950, was a young man coming from neo-pagan traditionalism. He had a conversion, due also to an experience of the Spiritual Exercises of St. Ignatius preached by Padre Lodovico Barrielle (1897 -1983), and so, a genuine religious vocation matured in him and he entered the seminary at Ecòne, where in 1978 he was ordained a priest by Mons, Marcel Lefebrve. As a result of his intellectual ability, he was nominated professor. I remember very well at that time, how he was fascinated by the theses of Father Guèrard de Lauriers (1898-1988), noted for his “theses of Cassiciacum”. According to these, from 1965 all the Popes are popes only in “materialiter” (accepting the scholastic term). Father de Lauriers, unlike Abp. Lefebvre , retained, that a Council cannot be erroneous in its decisions: the fact that some conciliar documents were in objective and undoubted contradiction with the perennial Magisterium of the Church, the Pope who had promulgated them, and his successors who had accepted them, by doing so, had lost at least on a formal level, their supreme authority. With this thesis, Father de Lauriers distanced himself from Abp. Lefebvre and in 1981 was consecrated a bishop, validly, but illicitly, by the emeritus Archbishop of Hué, the Vietnamese, Pierre Martin Ngò Dinh Thuc (1897-1984).
Fr. Piero Cantoni was not moved to take the hazardous step some of his religious brothers made by following Father de Lauriers, but he did not renounce the theological ideas which he had absorbed from the French Dominican, though he turned the terms upside down. Recognizing the supreme authority of the Pope, he concluded that the documents that he had retained contradictory with the Magisterium of the Church until then, should (now) have to be considered coherent with it. This simplistic equation, The Council = infallibility, veered towards sedevacantism or towards “concilarism ”. In 1981, Fr. Cantoni left the seminary at Ecòne with a group of Italian seminarians, was incardinated in the diocese of Apuania, became a parish priest and enrolled in the Lateran University, where he was welcomed in great charity by Mons. Gherardini. He graduated under the Monsignor’s guidance with research done on the “Novus Ordo Missae”. From 1973, the periodical Alleanza Cattolica “Cristianità” had hosted the writings of Abp. Marcel Lefebvre, Abp. Antonio de Castro Mayer and other traditional authors. In 1981,this relationship changed course, influenced by the theological inspirations of Fr. Cantoni. Abp. Lefebvre, and most of the so-called ‘traditionalist’ world, maintained a different position from the “sedevacantists” and the “concilarists” with which Fr. Cantoni was aligned.