One who refuses to accept, or questions, a teaching of the Roman Catholic Church (RCC) may be accused of reliance upon private judgment and failure to submit to the Magisterium or teaching authority of the Church.  Two observations on this accusation.

First, for many of us private judgment is not merely private, based as it is on consultation with many, many public sources.  It is as public as private. Everything I've read over the years from Parmenides on down in the West, the Bible on down in the Near East, and the Upanishads on down in the Far East feeds into my 'private' judgment.  So my 'private' judgment is not merely mine as to content inasmuch as it is a collective cultural upshot, albeit processed through my admittedly fallible and limited pate. Though collective as to content, its acceptance by me is of course my sole responsibility.  My first point, then, is that we ought to distinguish wider and narrower senses of 'private' and realize that a 'private' judgment might not be merely private.

Second, the party line or official doctrine of any institution is profoundly influenced by the private judgments of individuals. Think of the profound role that St. Augustine played in the development of Roman Catholic doctrine.  He was a man of powerful will, penetrating intellect, and great personal presence.  He was trained in rhetoric in Carthage and in Rome. Imagine going up against him at a theological conference or council!   

Summing up the two points, the private is not merely private, and the official is not merely official.

Of course, part of the official doctrine of the Roman church is that its pronunciamenti anent faith and morals are guided and directed by the Holy Ghost. (Use of the old phrase, besides chiming nicely with der Heilige Geist, is a way for this conservative to thumb his nose at Vatican II-type innovations which, though some of them may have had some sense, tended to be deleterious in the long run.  A meatier question which I ought to take up at some time is the one concerning the upsurge of priestly paederasty after Vatican II: post hoc ergo propter hoc? That should give pause to any one thinking of swimming the Tiber. Rod Dreher, who took the plunge, kept swimming, eastward. We could say he swam the Tiber first, and then the Bosporus, when, disgusted by priestly paedophilia, and the RCC's mafia-like protection of their own, he embraced Eastern Orthodoxy.)

What I have just written may sound as if I am hostile to the Roman Church. I am not. Nor have I ever had any negative experiences with priests, except, perhaps to have been bored by their sermons. All of the ones I have known have been upright, and some exemplars of the virtues they profess.  In the main they were manly and admirable men.  But then I'm an old man, and I am thinking mainly of the pre-Vatican II priests of my youth. 

I have no time now to discuss the Church's guidance by the third person of the Trinity, except to express some skepticism: if that is so, how could the estimable Ratzinger (Pope Benedict XVI) be followed by the benighted Bergoglio? (Yes, I am aware that there were far, far worse popes than the current one, and I am aware of  the theme of Satan's grip on the sublunary.)

Of course, I have just, once again, delivered my private judgment. But, once again, it is not merely private inasmuch as it is based on evidence and argument: I am not merely emoting in the manner of a 'liberal' such as Bergoglio when he emoted, in response to the proposed Great Wall of Trump, that nations need bridges, not walls. What an unspeakably stupid thing to say! Well, then, Vatican City needs bridges not walls the better to allow jihadis easy access for their destructive purposes. Mercy and appeasement must be granted even unto those who would wipe Christianity from the face of the earth, and are in process of doing so.

But how can my judgment, even if not merely private, carry any weight, even for me, when it contradicts the Magisterium, the Church's teaching authority, when we understand the source and nature of this authority? ('Magisterium' from L. magister, teacher, master.)

By the Magisterium we mean the teaching office of the Church. It consists of the Pope and Bishops. Christ promised to protect the teaching of the Church : "He who hears you, hears me; he who rejects you rejects me, he who rejects me, rejects Him who sent me" (Luke 10. 16). Now of course the promise of Christ cannot fail: hence when the Church presents some doctrine as definitive or final, it comes under this protection, it cannot be in error; in other words, it is infallible. 

In a nutshell: God in Christ founded the Roman church upon St. Peter, the first pope, as upon a rock. The legitimate succession culminates in Pope Francis. The Roman church as the one true holy catholic and apostolic church therefore teaches with divine authority and thus infallibly. Hence its teaching on indulgences not only cannot be incorrect, it cannot even be reasonably questioned. So who am I to — in effect — question God himself?

Well, it is obvious that if I disagree with God, then I am wrong.  But if a human being, or a group of human beings, no matter how learned, no matter how saintly, claims to be speaking with divine authority, and thus infallibly, then I have excellent reason to be skeptical. How do I know that they are not, in a minor or major way, schismatics diverging from the true teaching, the one Christ promised to protect?  Maybe it was some version of Eastern Orthodoxy that Christ had in mind as warranting his protection.

These and other questions legitimately arise in the vicinity of what Josiah Royce calls the Religious Paradox. 

One last point for today. My friend and colleague questions above "the ardent 'individualism' at the heart of  Protestantism." This point, however, needs some qualification inasmuch as Martin Luther, while anti-Rome, was not anti-Church.  He was certainly no maverick theologian preaching his own 'personal,' 'individualistic' truth. In his battle with the Anabaptists, Luther is decidedly anti-papist, but not anti-Church. Luther thought that the Anabaptists, Zwinglians, Schwenckelfeldians, et al. ". . . threatened the Reformation cause because  together they formed a common front repudiating Church and society." (Heiko A. Oberman, Luther: Man between God and the Devil, Yale UP, 2006, p. 229)

If what Protestants want is a reformed church, then they want a church, which will have its 'confession,' its compendium of defining doctrines and prescribed and proscribed practices that would be binding upon and thus authoritative for anyone who wanted to belong to that church.   If so, the issue should not be framed as one between individualism and church authority, but as between one church authority versus another, for example Calvinists versus 'papists,' 'Romanists.'