Beginning in 1959, four departments in the College of Arts and Sciences appointed five medievalists who would play an instrumental role in the creation of a multi-disciplinary medieval studies program that covered several medieval languages and literatures, including English, French, Italian, German, Occitan Latin, Greek, and Hebrew.

In 1959 Brian Tierney (B.A., 1948, Ph.D., 1951, Cambridge) was hired by Cornell as Full Professor of Medieval History. Tierney was born in 1922 in North Lincolnshire and served with distinction in the Royal Air Force during World War II. After the war, Tierney and his wife, Theresa, moved to the United States, where he taught for eight years at the Catholic University in Washington, D.C. After joining the Cornell faculty, one of his first projects was to study a treatise by Saint Antoninus (1389-1459), Archbishop of Florence, printed in Nuremberg by Koberger between 1477 and 1479 and given to Cornell in 1960 by the University Library Associates (Division of Rare Books and Manuscripts BX1749 A63+++).

Between 1955 and 1964, Tierney published three important monographs: Foundations of the Conciliar Theory: the Contribution of the Medieval Canonists from Gratian to the Great Schism (Cambridge University Press, 1955); Medieval Poor Law: a Sketch of Canonical Theory and its Application in England (University of California Press, 1959); and Crisis of Church and State, 1050-1300 (Prentice-Hall and Spectrum Books, 1964). In 1964, in recognition of his “disciplinary breadth and acumen and the ecumenical significance of his work,” he was awarded an honorary Doctorate of Theology from the Uppsala University. In 1966, he was awarded a grant from the American Council of Learned Society for study in Europe, where he lectured in Munich, Bonn, Freiburg, Aachen, Saarbrucken, Salzburg, Leiden, Groningen, and Nijmegen. In 1969 he became Goldwin Smith Professor of Medieval History at Cornell.

Tierney argued that the modern concepts of democracy and natural rights have their origins in the Middle Ages. He did not shy away from academic controversy, and his intellectual audacity, together with his congenial personality attracted many Cornell students to his courses. The author of an article in the Cornell Daily Sun (April 17, 1963) observed that “one Anglophile was impressed most by Tierney’s accent and moustache.”

In 1972 Tierney—a practicing Roman Catholic who had served as President of the American Catholic Historical Association–published his Origins of papal infallibility, 1150-1350: a study on the concepts of infallibility, sovereignty and tradition in the Middle Ages (Leiden, E. J. Brill), in which he challenged the doctrine of papal infallibility as defined by the First Vatican Council of 1869-70. According to Tierney, the seeds of the doctrine of papal infallibility had been sown by members of the Franciscan order in the thirteenth century for the sake of political convenience. Previously, Tierney contended, papal infallibility played no part in the canonical tradition. To this he added that “the papacy adopted the doctrine out of weakness. Perhaps one day the Church will feel strong enough to renounce it.” The book triggered a scholarly exchange or debate, published in issues of one English and one Italian journal, between Tierney and Msgr. Alfons Maria Stickler (1910-2007), the Prefect of the Apostolic Vatican Library. Some thirty years after the book was published, a summary of the subsequent controversy in the New Catholic Encyclopedia noted that “[m]ost scholars recognize that Tierney correctly located in the late 13th century the first discussions of papal infallibility” and added that, as regards other points raised in the work, “the discussion continues.”
In 1969 Tierney became Goldwin Smith Professor of Medieval History and in 1977 he was chosen as the first Bowmar Professor of Humanistic Studies at Cornell. In 1980 he was elected to the American Academy of Arts and Sciences; and in 1981 he received an honorary Doctorate of Humane Letters from the Catholic University of America “for his contributions to medieval studies and to the academic profession generally.”