Papal infallibility

Papal infallibility is the Catholic doctrine that the pope is preserved from error when definitively teaching on faith or morals for the whole Church. It does not mean every papal statement or action is infallible.

Ex cathedra: A solemn papal act of teaching from the chair of Peter, defining doctrine on faith or morals for the whole Church. This is the specific mode in which papal infallibility is exercised.
First Vatican Council: The 1869–1870 ecumenical council that defined papal primacy and infallibility. Its constitution Pastor aeternus gave the doctrine its formal definition.
Henry Edward Manning: An English Catholic cardinal and theologian who strongly supported defining papal infallibility at Vatican I. He became one of the definition's most prominent defenders.
Papal impeccability: The mistaken idea that a pope is incapable of sin or moral failure. Infallibility concerns defined teaching, not the pope's personal virtue.
Old Catholic Church: A group of churches formed by Catholics who rejected the First Vatican Council's definition of papal infallibility. Some opponents organized separate communities after the council's decision.
Dogmatic definition: A definitive statement of doctrine proposed as binding on the faithful. The doctrine concerns definitive teaching, not provisional judgments or casual remarks.
Pastor aeternus: The First Vatican Council's 1870 constitution defining papal primacy and infallibility. This document states the conditions and scope of the definition.
Ignaz von Döllinger: A German Catholic historian and theologian who opposed the definition of papal infallibility and was excommunicated after rejecting it. His opposition shows the controversy the council's decision provoked.
Papal infallibility and the Immaculate Conception: A common comparison between the 1854 papal definition of the Immaculate Conception and the later formal definition of papal infallibility. The 1854 definition preceded Vatican I, but did not itself define the doctrine of infallibility.
Papal conclave: The process by which eligible cardinals elect a pope. The doctrine concerns the pope's teaching, not the process that selects him.

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