A faithful and intelligent Catholic, New York Times opinion writer Ross Douthat, offers some helpful reflections on papal infallibility:
On paper, that doctrine seems to grant extraordinary power to the pope—since he cannot err, the First Vatican Council declared in 1870, when he “defines a doctrine concerning faith or morals to be held by the whole Church.”
In practice, though, it places profound effective limits on his power.
Those limits are set, in part, by normal human modesty: “I am only infallible if I speak infallibly, but I shall never do that,” John XXIII is reported to have said. But they’re also set by the binding power of existing teaching, which a pope cannot reverse or contradict without proving his own office, well, fallible—effectively dynamiting the very claim to authority on which his decisions rest.
Infallibility is attractive—until you’re compelled to ascribe it to others in order to retain it yourself.