What's the deal with papal infallibility? Can the pope modify any church teaching he so desires, and Catholics would have to obey? Can he make abortion OK? What about worshipping Satan?
—Gabriel Andrade, Venezuela
Living in Venezuela, Gabriel, you may have seen the quirks of papal fiat up close. In the 16th century, according to legend, Spanish missionaries thereabouts petitioned the Vatican to allow newly converted locals to eat capybara (aka the world's largest rodent) during Lent, when Catholics are otherwise enjoined from eating meat. The pope agreed, essentially declaring the capybara—a fine swimmer, yes, but conspicuously four-legged and hairy—a fish. I'm told salted capybara remains a Lenten specialty down there. If that ain't infallibility, what is?
Alas. It turns out that, doctrinally speaking, papal infallibility is far weightier than this kind of casual transubstantiation; rendering mammals fish is merely one of the lesser perks of the job of pope, which comes with basically unchecked authority. Or at least within the domain of the Catholic Church: The notion of infallibility was cemented in the 1860s when Pope Pius IX faced external political threats and, by convoking the First Vatican Council, aka Vatican I, sought to shore up the power of his office.
Recall what was going on in the wake of the Enlightenment, the dominant European intellectual movement of the era preceding: the French Revolution, upheaval across the continent, a general emphasis on democracy over monarchy—as Kant put it, the end of an age characterized by "lack of courage to use one's own mind without another's guidance." In this context, many looked seriously askance at a hierarchical outfit like the Roman church. Priests were booted from France; in Italy, nationalists seized and redistributed property owned by the church, eventually whittling the pontiff's dominion down to one small plot of land in Rome: Vatican City. The feeling was mutual, of course. Among the considerations at Vatican I was a repudiation of "progress, liberalism and modern civilization." (A contemporaneous account in The New York Times called the gathering the "last protest of the representative of the Middle Ages against the spirit of the Nineteenth Century.")
Thus, in hopes of giving the pope a little boost, was the notion of papal infallibility formalized. It wasn't a new idea, but the council put it in writing. There are two criteria, essentially, for an infallible pronouncement: that it be made ex cathedra—literally, "from the chair," i.e., in the pope's capacity as the church's supreme leader—and that it concern "faith and morals." So: could the pope declare a surprising about-face with respect to abortion or the Prince of Darkness? Insofar as either would seem to involve faith and morals, well, why not? But perhaps it's instructive to think of the pope's relationship to infallibility like the U.S. president's relationship to the nuclear codes. Sure, he's got the authority and the means to launch a war on a whim—but history, political pressure, the expected aftermath, etc., all conspire to incentivize a sober, rational decision. In the president's case, too nutty a move and he faces impeachment, maybe a coup. The pope doesn't have to worry about that—there's no mechanism for his removal—but one assumes a wholesale embrace of Satanism might cause a bit of a rift among the flock.
So extreme is the infallibility option that popes have typically been leery of going there: As John XXIII (1958-1963) put it, "I am only infallible if I speak infallibly, but I shall never do that, so I am not infallible." Further, debate continues over whether certain pronouncements were in fact infallible or just, you know, pronouncements:
What everyone can agree on is that the Virgin Mary's Assumption into heaven is dogma, made so by Pius XII in his 1950 Munificentissimus Deus.
You'll hear Catholics speak of this being one of only two instances where infallibility was invoked; the other they're referring to is Pius IX's affirmation of the Immaculate Conception. This was in 1854, though—i.e., several years before papal infallibility was itself declared dogma at Vatican I—so some might exclude it on a technicality. Others consider infallibility to apply retroactively not only to this but to other foundational pronouncements popes have made throughout history—for instance, Leo I on the two natures (divine and human) of Christ, circa 449 AD.
Some, including the former Pope Benedict, have argued that a 1994 statement by John Paul II rejecting the possibility of female priests was infallible. This is far from settled, the counterargument being that the word "infallible" appears nowhere in the document; JPII called his pronouncement simply "definitive." The stakes are higher than they sound: Benedict was subsequently criticized for promoting "creeping infallibility," or endeavoring to quietly move certain hot-button issues—women's ordination, contraception—outside the realm of debate by suggesting they're more settled than they actually are.
Faced with much Protestant sniffing about the whole idea, Catholics are keen to stress that infallibility doesn't equate to impeccability—being without sin—nor does it mean that the pope considers himself immune from error. Pontiffs probably don't suffer in the self-regard department, in other words, but it's not like they're Donald Trump. CW
Send questions to Cecil via StraightDope.com or write him c/o Chicago Reader, 350 N. Orleans, Chicago 60654.