On the one hand, the Roman Catholic Church teaches in Dei Verbum that the living teaching office of the Church is “not above the word of God, but serves it, teaching only what has been handed on, listening to it devoutly, guarding it scrupulously and explaining it faithfully in accord with a divine commission and with the help of the Holy Spirit, it draws from this one deposit of faith everything which it presents for belief as divinely revealed” (DV 10).
On the other hand, consider the following argument. If knowledge is to be infallible, there cannot be a distance or difference between the knower and the thing known. This is because such a “distance” would otherwise have to be spanned hermeneutically, through a decision to think about the object in a certain way and to confirm that mode of thinking in an experience. (See the discussion here.) And because it involves making a decision to interpret a thing in some way or another, it is always fallible. The interpretive decision could have been mistaken, or one’s experiences could be equally compatible with a different interpretation, and so on. Thus, knowledge of a thing distinct from oneself is always fallible. But knowledge which involves no distance between the knower and the thing known is precisely self-knowledge. Thus, object-knowledge is fallible whereas self-knowledge is infallible.
A simple illustration can bring the point to light. Suppose I see something that I judge to be a cat sleeping on a ledge. I can be mistaken about a number of things in my judgments: perhaps that thing over there is not a cat, perhaps it is not sleeping, and so on. But I cannot be mistaken that I am having a certain visual experience. That is because, although the cat is “outside” of me and distinct from me in some sense, my experience is simply a mode of my own life. There is not a “distance” between myself and my experiencing a certain visual state.
It is now possible to give the following argument. The magisterium of the Church cannot simultaneously be infallible in its teaching and a servant of the Word it receives. This is because serving the Word means accepting a fundamental distinction between the servant and the served, the one being an object to the other. On the other hand, the Church can only be infallible if what it knows and teaches is itself, since only self-knowledge is infallible. Thus, either the Church is a servant to the Word and thus fallible in what it teaches, or else it is infallible only because it teaches itself, but it cannot be both. The Church either teaches about God, in which case it can be mistaken, or else it teaches what it believes about God, in which case it is only infallible insofar as it is describing itself.
Roman Catholic theologians often speak in both ways. For example, alongside the above citation from Dei Verbum, one can also find the following statement: “the Church, in her teaching, life and worship, perpetuates and hands on to all generations all that she herself is, all that she believes” (DV 8). But although it is true that the Church hands down what it itself is to all generations, much like any institution or tradition, it cannot be infallible to the extent that it admits a distance between herself and what she teaches.
In fact, to the extent that the Church asserts its own infallibility, it arguably deifies itself and makes itself the truth that it preaches. This becomes evident in the dialectic about infallible teaching and irreformable statements.
Avery Cardinal Dulles, Magisterium: Teacher and Guardian of the Faith (Sapientia Press, 2016) describes the Roman Catholic position on the “irreformable” statements made when the magisterium teaches infallibly as follows. On the one hand, infallibly taught statements are “irreformable” to the extent that “the statements are not subject to rejection or correction by any other authorities in the Church” (p. 66). On the other hand, he recognizes that “Irreformable statements may, however, require completion, refinement, reinterpretation, and restatement in accordance with new conditions, which raise new questions and provide new information, new conceptual categories, new methods, and new vocabulary,” so that “The ‘irreformability’ of a definition, though it rules subsequent reversals, leaves room for considerable ‘reformulation’” (ibid.).
This raises the obvious question: Who can be a judge of whether or not a later “completion, refinement, reinterpretation, or statement” is not really a “reversal”? The only possible answer is: the Magisterium of the Church. Thus, the Magisterium can teach infallibly, utter irreformable judgments, and be itself the sole ultimate authority on the interpretation of its own irreformable statements. The Magisterium is itself the faith that it teaches, contrary to its own statements, rather than its faith being directed toward something outside of it and to which it submits.