Pope Benedict XVI announced on Sunday that he is "deeply sorry" for quoting a passage that calls the teachings of Mohammed "evil and inhuman" during a lecture last week. Wait a minute, isn't the pope supposed to be infallible?
Yes, but only in certain circumstances. The principle of papal infallibility doesn't mean that the bishop of Rome can't commit a sin or say the wrong thing. It refers only to a very specific situation—when the pope is making a solemn decree ex cathedra (or "from the seat") on a matter of faith or morals. In general, a pope who wants to make an infallible statement will make sure that everyone knows what's going on. He might punctuate his decree, for example, with the warning that anyone who denies it will have fallen away from the Catholic faith.
Only one pope—and only one papal decree—has ever invoked this kind of infallibility since it was first defined. In 1950, Pius XII declared the Assumption of Mary (i.e., the quick passage of her body and soul into heaven) as a dogma of the church. The language of the decree made his invocation of infallibility very clear: "We pronounce, declare, and define it to be a divinely revealed dogma … "
The tradition vesting the pope with absolute authority goes back centuries, but papal infallibility didn't become a formal doctrine until the first Vatican Council in 1870. This was seen as something that had always been true and was only now being recognized in an official capacity. That means that papal decrees from before 1870 could be viewed as infallible if the right conditions were met. Some theologians see Pius IX's 1854 decree on Mary's Immaculate Conception as a clear example of papal infallibility, even though the principle hadn't yet been laid out.
The Second Vatican Council tweaked the definition in the 1960s. According to current church doctrine, there are two kinds of infallibility: ordinary and extraordinary. Ordinary infallibility applies when bishops in all parts of the world end up teaching the same thing with respect to faith and morals. In his pre-pope days, Cardinal Ratzinger declared (on behalf of John Paul II) that the ban on women priests "has been set forth infallibly." He didn't mean the pope had made an infallible decree but rather that the principle had been upheld through the universal teachings of the church.
Extraordinary infallibility applies to the pope himself, "in virtue of his office." That means he can only make infallible statements once he's been installed in the Vatican. (Ratzinger's pre-papal comments wouldn't fall under the definition, for example.) Ecumenical councils—like the First and Second Vatican Councils—are also infallible when they make solemn decrees on faith and morals.
Got a question about today's news? Ask the Explainer.