During the first millennium, popes functioned largely as mediators. They did not appoint bishops, impose clerical celibacy or write encyclicals for the whole church. During the second millennium, however, the papacy swung sharply in the direction of central control over the worldwide church. McBrien includes an excellent, nuanced explanation of the evolution of the doctrine of papal infallibility, noting that the concept was not formally applied to the papacy until the fourteenth century and was not explicitly defined until 1870 at the First Vatican Council. Vatican II provided further context, making it clear that, in principle, the whole Church not just the pope and other bishops acting with him is infallible in faith and morals.
Individual popes can, and do, make mistakes in matters of doctrine.
In the end, perhaps McBrien's greatest contribution is to raise our awareness of the evolution of the papacy and to demonstrate that popes are much like priests, sisters and laypeople sometimes frail, sometimes misguided, and yet capable of inspired leadership and faithfulness to Jesus' teachings. Bill Williams is letters editor of The Hartford Courant. Last revised, February 22, 1997.