Papal infallibility is one of the most distinctive teachings of the Catholic Church. It is also one of the most widely misunderstood. The Church’s critics imagine that Catholics are bound to blindly believe every word a pope says. A fair number of Catholics behave as though they are.
Sooner or later, it happens to every Catholic. The pope says something, usually in an encyclical, a General Audience, or an aeroplane press conference, and the honest first reaction, arriving before piety can catch it, is: ‘I do not think that is right’. What happens next is usually one of two mistakes. The first is panic: if the pope said it, it must be true; I disagree; therefore, something is wrong with me, or with the Church. The second mistake is the shrug: he is only infallible like once or twice a century, so the rest can be ignored, like the weather. One reflex treats every papal sentence as a dogma. The other treats none of them as anything. Both are the same mistake: each flattens the Church’s teaching authority into a single switch, either permanently on or permanently off. The tradition is more careful than that, and far more interesting.
What Infallibility Actually Is
The First Vatican Council defined the doctrine in 1870, and its conditions are strict. As Pastor Aeternus, the Council’s dogmatic constitution, puts it, the pope teaches infallibly only:
“when, in the exercise of his office as shepherd and teacher of all Christians, in virtue of his supreme apostolic authority, he defines a doctrine concerning faith or morals to be held by the whole Church.”
Every clause narrows the field. Not the pope musing, not the pope being interviewed: the pope solemnly defining, on faith and morals, for the whole Church. The two examples every Catholic knows are the Immaculate Conception in 1854 and the Assumption in 1950. They are the clearest cases, but not the only ones. There is no official list, and the tradition has long recognised other exercises of the same power, from Leo the Great’s Tome on the natures of Christ in 449, received at Chalcedon with the cry “Peter has spoken through Leo”, to Benedict XII’s definition on the beatific vision in 1336. A power Peter has always held is not made more believable by pretending it has scarcely ever been used.
Note what the doctrine does not say. It does not make the pope inspired, or sinless, or always right; popes go to confession like the rest of us. Infallibility is a negative protection: in that one narrow, solemn act, God will not allow the pope to bind the Church to error or heresy.
Three Levels of Teaching
Beneath the definitions, the tradition distinguishes, and the distinctions decide everything. The word to know here is assent, which simply means the mind’s yes: accepting a teaching as true and holding to it. Obedience. At the first level are truths revealed by God and infallibly proposed as such, whether by solemn definition or by the ordinary and universal teaching of the pope and the bishops together: the contents of the Creed, the dogmas of the faith. These call for the assent of faith itself; to deny one knowingly is heresy. At the second level are truths not revealed but so bound up with revelation that the Church teaches them definitively: that a certain council was valid, that a certain saint is in glory. These too, are held on faith in the Church’s authority.
Then comes the third level, where nearly all everyday teaching lives: the ordinary, non-definitive magisterium: encyclicals, exhortations, the instruction of bishops and of Rome. Here the Church asks neither the assent of faith nor mere polite attention. As the Code of Canon Law, in Canon 752, puts it:
“Although not an assent of faith, a religious submission of the intellect and will must be given to a doctrine which the Supreme Pontiff or the college of bishops declares concerning faith or morals when they exercise the authentic magisterium, even if they do not intend to proclaim it by definitive act.”
The Catechism of the Catholic Church, in paragraph 892, describes the same response and settles its spirit: “To this ordinary teaching the faithful are to adhere … with religious assent which, though distinct from the assent of faith, is nonetheless an extension of it.”
“Religious submission of intellect and will” sounds severe and means something quite humane: docility. The presumption that the Vicar of Christ, teaching on faith and morals, is right, and the sustained effort to understand him before presuming to contradict him. Docility is not the switching off of the mind. It is the discipline of not switching it off in one’s own favour.
An Interview Is Not an Encyclical
Within that third level, weight varies enormously, depending on the document, the office and the subject matter. A rough descending order would typically be: a conciliar constitution; an encyclical; an apostolic exhortation or letter; a general audience or homily; and, somewhere near the bottom, an off-the-cuff remark: an aeroplane press conference, an answer given point-blank to a reporter’s question, a line lifted from an interview, and a tweet. When a pope answers a microphone, he did not choose, on a question he did not set, he is not solemnly teaching the whole Church; he is a pastor thinking aloud. Treating the aeroplane answer as an encyclical is a category error committed daily by the pope’s critics and his fans alike.
Immigration is the tidy example, because the off-the-cuff remarks on it have scandalised both camps in turn: one year a pope’s comment about walls, another year a pope’s comment about a nation’s right to secure its borders. Meanwhile, the Catechism, in a single article, instructs the prosperous nation to welcome the foreigner “to the extent they are able” and instructs the foreigner to obey the laws of the nation that receives him. The principles are doctrine. Which visa regime honours them is not settled in heaven; it is prudential judgment, a matter of practical wisdom about changing circumstances, on which serious Catholics may soberly differ. Most outrage, in any case, is directed not at what a pope wrote but at a headline’s paraphrase of it. The pope is quoted far more often than he is read.
What Disagreement Is Not
None of this licenses a Catholic to “disagree” with the teaching of the Church. The Creed is not up for a vote. The moral law is not an offhand remark. The deposit of faith, the first two levels above, is precisely what the whole structure exists to hand on intact, and withholding assent there is not an opinion but a departure. What the tradition permits is narrower and humbler: on non-definitive, prudential matters, a Catholic who has done the work may find the presumption in the pope’s favour overcome. Even then, his difficulty is to be held provisionally, expressed respectfully, and weighed against who he is. A theologian who has spent forty years on the question and a guy with a laptop do not hold the same license.
The rules, then, are not complicated. Read what was actually said: the document, not the screenshot. Establish at what level it was said. Let the presumption favour the pope, who has the office and the grace of state. And where honest difficulty survives all that, hold it quietly and stay at the table. Disagreement of that kind is permitted. Contempt is not. Neither is a parallel magisterium run from a social media account or focus group.
The Church has lived with this tension from the beginning and survived it. St Paul questioned the first pope “to his face” at Antioch, and the Holy Spirit preserved the account in Scripture. In the fourteenth century, John XXII preached, expressly as his private opinion, an error about the souls of the blessed; the faithful objected, he retracted before his death, and his successor, Benedict XII, defined the truth in Benedictus Deus, the very definition of 1336 mentioned above. The correction came through faithful argument inside the Church.
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