Probably sedevacantists’ main problem is the Church’s infallibility (Conciliar Popes are horribly fallible, so how can they be Popes?). However, infallibility needs to be looked at for more than just to alleviate sedevacantism. The modern problem of preferring authority to truth is vast.
“Infallibility” means inability to err, or to fall into error. The First Vatican Council defined in 1870 that the pope cannot err when four conditions are present: he must (1) be speaking as Pope, (2) on a question of Faith or morals, (3) in a definitive fashion, and (4) with the clear intention of binding the whole Church. Any such teaching belongs to what is called his “Extraordinary” Magisterium, because on the one hand Popes rarely engage all four conditions, and on the other hand he teaches many other truths which cannot err or be wrong because they have always been taught by the Church, and therefore they belong to what Vatican I called the Church’s “Ordinary Universal Magisterium,” also infallible. The question is, how does the Pope’s Extraordinary Magisterium relate to the Church’s Ordinary Magisterium?
Mother Church teaches that the Deposit of Faith, or public Revelation, was complete at the death of the last Apostle alive, say, around 105 AD. Since then no further truth has been added, or could be added, to that Deposit, or body of revealed truths. Then no “extraordinary” definition can add one iota of truth to that Deposit, it only adds, for the sake of believers, certainty to some truth already belonging to the Deposit, but whose belonging had not been clear enough beforehand. In a fourfold order comes firstly, an objective REALITY, independent of any human mind, such as the historical fact of the Mother of God’s having been conceived without original sin. Secondly comes TRUTH in any mind conforming itself to that reality. Only thirdly comes an infallible DEFINITION when a Pope engages all four conditions to define that truth. And fourthly arises from that definition CERTAINTY for believers as to that truth. Thus whereas reality generates the truth, a Definition merely creates certainty as to that truth.
But the reality and its truth already belonged to the Ordinary Magisterium, because there is no question of any Pope defining infallibly a truth outside of the Deposit of Faith. Therefore the Ordinary Magisterium is to the Extraordinary Magisterium as dog is to tail, and not as tail to dog! The problem is that the Definitiom of 1870 gave such prestige to the Extraordinary Magisterium that the Ordinary Magisterium began to pale in comparison, to the point that Catholics, even theologians, scratch around to fabricate for it an infallibility like that of the Extraordinary Magisterium. But that is foolishness. The Extraordinary presupposes the Ordinary Magisterium, existing only to give certainty (4) to a truth (2) already taught by the Ordinary Magisterium.
Let the point be illustrated from a snow-capped mountain. The mountain in no way depends on the snow, except for it to be made even more visible than it already is. On the contrary the snow depends completely on the mountain to be where it, the snow, is. Similarly the Extraordinary Magisterium does no more for the Ordinary Magisterium than to make it more clearly or certainly visible. As winter closes in, so the snowline descends. As charity grows cold in modern times, so more definitions of the Extraordinary Magisterium may become necessary, but that does not make them the perfection of the Church’s Magisterium. On the contrary, they signal a weakness of believers’ grasp of the truths of their Faith. The healthier a man is, the fewer pills he needs. Next week, the application both to sedevacantism and to the present crisis of the SSPX.