There are two common and distinct approaches to the question of the infallibility of the Church’s teaching authority. Non-Catholics deny that any human person or institution can be infallible in any meaningful way. Many Catholics, by contrast, hold that the Church can and does teach infallibly on matters pertaining to faith and morals — except when she teaches something they don’t want to believe.
Infallibility is at the same time one of the most controversial and least understood dogmas of the Catholic Church. Even people who do understand infallibility argue over what teachings it covers and doesn’t cover, while others make errors of distinction between dogma, to which infallibility does apply, and discipline, to which it does not. (Discipline refers to the liturgical and ecclesiastical practices of the Church; e.g., clerical celibacy and meatless Fridays.) Moreover, many Catholics themselves are confused as to the extent of the Church’s teaching authority; they understand there are issues to which the Church can’t speak … but not that the Church isn’t strictly limited by its nature to commenting only on religious issues.
The What and Why of Infallibility
Let’s start off simply: What do we mean by infallibility? To say that the Church teaches infallibly is simply to say that the Church can’t teach errors; put differently, you can safely trust what she teaches. That, however, doesn’t mean that any given teaching is necessarily perfect. Let me draw an analogy: If I were to ask a class of math students, “What is the sum of two plus two?”, they could answer “an even number”, “an integer”, or “a real number”; these answers are all correct, even though none of them is necessarily the best answer to the question.
Why would the Church need infallibility? Jesus’ mandate to the apostles was to “make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit, teaching them to observe all that I have commanded you” (Matthew 28:19-20). The Church exists to teach what Jesus and the apostles taught — not what they should have taught, not what they would have taught “had they known what we know now.” The doctrine of infallibility asserts that Christ himself guarantees the integrity of the gospel message through the guidance of the Holy Spirit.
What Scriptural basis do we have for asserting the Church’s infallibility? First, at the Last Supper, Jesus promised the apostles, the leaders of his Church, that the Father would send them the Holy Spirit to “teach [them] all things, and bring to [their] remembrance all that I have said to [them]” (John 14:26), and that the “Spirit of truth” would “guide [them] into all the truth” (John 16:13). Moreover, Jesus promised to be with his Church “always, to the close of the age” (Matthew 28:20). Also, St. Peter reminds his audience that the apostles have “the prophetic word made more sure,” and that prophecy, such as those recorded in the Old Testament, doesn’t come “by the impulse of man, but men moved by the Holy Spirit [speak] from God” (2 Peter 1:19-21). And St. Paul called the Church “the pillar and bulwark [or foundation] of the truth” (1 Timothy 3:15).
The quality of infallibility, then, isn’t a function of the holiness, the wisdom, or the zeal of the Church’s leadership. Indeed, Hilaire Belloc once quipped that “no merely human institution conducted with such knavish imbecility would have lasted a fortnight.” Rather, it’s lent to the Church, through the guidance of the Holy Spirit and the presence of Christ with his Church; ironically, Protestant preachers, especially Evangelicals, assert this same guidance even as they deny infallibility to anything but Scripture.
The Infallible Magisterium
Most of the Church’s infallible teachings, or dogmas (also called dogmata), have been explicitly declared in the canons and decrees of various ecumenical councils. (Key distinction: dogmas are irreformable; doctrines can be modified.) Infallibility assumes that the ecumenical council is not only “in communion with the pope” (i.e., having papal approval) but has gone to great lengths to declare their permanence, very often anathematizing those people who would contradict them.
Other infallible dogmas are stated in the creeds, particularly the Apostles’ Creed and the Niceno-Constantinopolitan Creed. Anything that’s part of the deposit of divine revelation is considered infallible; in fact, infallibility assumes that the doctrine is either directly revealed or closely connected to the revelation.
The First Vatican Council in its fourth session on July 18, 1870, formally defined and declared the infallibility of the pope. I refer you to an online copy of the Council’s First Dogmatic Constitution on the Church of Christ, which set out their historical and theological rationale; for our purposes, we need only discuss its limits. Strictly speaking, infallibility is only granted to the pope “when [he] speaks ex cathedra, that is, when,  in the exercise of his office as shepherd and teacher of all Christians,  in virtue of his apostolic authority,  he defines a doctrine concerning faith or morals to be held by the whole Church” (First Dogmatic Constitution, 9).
As defined by the Council, this is such an extraordinary exercise of the papal teaching office that only two pontifically-declared dogmas are universally agreed to fit the criteria: the Assumption and the Immaculate Conception. The point is, not everything that falls out of the pope’s mouth or comes out of his pen is indisputably infallible; in fact, Pope Emeritus Benedict XVI wrote his series on Jesus under his baptismal name, Joseph Ratzinger, specifically to avoid any claim of infallibility. Certainly Pope Francis’ off-the-cuff remarks and media interviews aren’t covered!
The Fallible Magisterium
The extraordinary measures of councils and popes are referred to collectively as the sacred magisterium. By contrast, the ordinary magisterium of the Church is the everyday exercise of her teaching authority, in which neither the pope nor any council of bishops goes so far to cast doctrine in concrete (but see below). Doctrines can and do develop, especially as time, technological development, and the ever-inquisitive nature of Man create questions and issues that require the Church’s attention; e.g., Catholic social teaching.
Confusingly, there is also a class of teachings that belong to the ordinary and universal magisterium, which despite the name are actually part of the sacred magisterium, and are also considered infallible even though not defined and decreed as are other dogmas. One particularly controversial example is the restriction of ordination to men alone, as reaffirmed by Pope St. John Paul II in his apostolic letter Ordinatio Sacerdotalis in 1994 (see the Congregation for the Doctrine of the Faith’s ad dubitum response issued 28 October 1995).
Take note that the Church’s magisterium applies to matters of both faith and morals. While not every field of human endeavor has an application pertaining to matters of faith, most if not all have a moral dimension. Thus, for instance, the pope couldn’t tell economists how to properly discern the gross domestic product of a nation, or how to correctly define the marginal propensity to consume; he can, however, properly talk about the right to fair wages and the universal destination of goods. It’s nigh on impossible, then, to draw bright lines that set off whole subjects as “outside the Church’s competence”, subjects about which the pope and the Church can only say things we can safely, blissfully ignore.
What Do I Not Have to Believe?
Okay, so let’s say you find a way to list every dogma the Catholic Church has concretized by formal declaration. You could even go to a source, like Dr. Ludwig Ott’s seminal work Fundamentals of Catholic Dogma, and obtain from it the theological weight of every teaching (at least up to 1954), from the highest (de fide, “of the faith”) to the lowest (opinio tolerata, “tolerated opinion”). Could you then openly dissent anything that isn’t at least “theologically certain”?
That in itself is debatable. While anything that’s been proposed “for belief as divinely revealed” must be “adhered to with the obedience of faith” (Catechism of the Catholic Church 891; cf. Dei Verbum 10.2, Lumen Gentium 25), there’s also this little catch-all:
Divine assistance is also given to the successors of the apostles, teaching in communion with the successor of Peter, and, in a particular way, to the bishop of Rome, pastor of the whole Church, when, without arriving at an infallible definition and without pronouncing in a “definitive manner,” they propose in the exercise of the ordinary Magisterium a teaching that leads to better understanding of Revelation in matters of faith and morals. To this ordinary teaching the faithful “are to adhere to it with religious assent” which, though distinct from the assent of faith, is nonetheless an extension of it. (CCC 892; cf. Lumen Gentium 25; italics mine)
“Divine assistance” can be considered a kind of lower-case infallibility. While not directly asserting that the teaching proposed is error-free, it implies that most if not all reasonable objections have already been raised and answered at least once, and that the doctrine is the best that can be offered at this time. As such, it’s theologically certain enough that the protection of the Holy Spirit can be reasonably presumed albeit not explicitly asserted. In any event, unless you’re a priest or degreed theologian with a mandatum from your local bishop, you’re on safer grounds not disputing even low-weight doctrines.
Critics may argue that the presumption of infallibility imposes a kind of “groupthink”, making doctrinal advance impossible. However, we must be careful to distinguish authentic reform from corrupting innovation. As I’ve said at immoderate length elsewhere, “The gospel message the Church exists to preach is not her own — it belongs to Christ.” This “groupthink” is the Church’s best protection, the best means we have to insure the integrity of the gospel message and of that continuity between us and the first generation of Christians we call the apostolic tradition. The evangelium is not a suit of clothes to be replaced with every change of cultural fashion; to paraphrase Cdl. Timothy Dolan, we can in a sense “re-wrap” the Faith for better understanding, but we can’t change what that wrapping packs.
Avoiding the Cafeteria Line
Catholic teaching is broad and deep; it’s difficult to know every dogma or doctrine, even if you went to good Catholic schools from kindergarten to college. As well, it’s safe to assert that Catholic religious formation has been suffering in the US for many decades, arguably even before Vatican II. The pejorative label “cafeteria Catholicism” isn’t meant to apply to defects of understanding and education, but rather to deliberate, conscious heterodoxy.
There are plenty of resources available, both online and at your local Catholic bookstore, to help you learn exactly what the Church believes, some of which I’ve linked to in this post. At the end of the day, though, no one can make you believe what the Church believes … except you yourself. As Fr. Dwight Longenecker recently wrote:
The Catholic Church needs diversity of opinion. It’s healthy for family members to disagree, and debate is one of the ways the Holy Spirit leads the Church. But both progressives and traditionalists must constantly measure their personal opinions and preferences against the magisterium of the Church and her authority.
Faith is ultimately an act of trust — trust in the truth of God, trust in the reliability of His Word, trust in the action of the Holy Spirit. The Church doesn’t ask you to trust the pope or the bishops; she asks you to trust in Christ’s promise that “the gate of Hades shall not prevail against” his Church (Matthew 16:18).
The author gratefully acknowledges the advice of John Médaille.