Collier's New Encyclopedia (1921)/Infallibility
INFALLIBILITY, a quality or state of freedom or exemption from error.
Papal infallibility, a claim defined on July 18, 1870, in the Œcumenical Council, held in the Vatican under the presidency of Pope Pius IX.
"We teach and define that it is a dogma divinely revealed that the Roman pontiff, when he speaks ex cathedrâ, that is, when in discharge of the office of pastor and doctor of all Christians, by virtue of his supreme apostolic authority he defines a doctrine regarding faith or morals to be held by the Universal Church, by the divine assistance promised to him in blessed Peter, is possessed of that infallibility with which the divine Redeemer willed that His Church should be endowed for defining doctrine regarding faith or morals; and that therefore such definitions of the Roman pontiff are irreformable."
Till the decision of the Vatican Council in favor of the Pope's infallibility this opinion, though for centuries it had had numerous advocates, especially in Italy, had never been authoritatively decided. When it ceased to be an open question, some German scholars, of whom Professor Döllinger, of Munich, was the most noted, seceded from the Roman Church, and in September, 1871, took the name of Old Catholics.