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Post
Nishant made a good point about universal acceptance of a Pope being the criterion for legitimacy. It make sense as the a priori establishment of the dogmatic fact of legitimacy. I think about this often and haven't come to a final resolution on the subject.
Let's say that a Pius XIII came along and declared BoD to be heretical. You, I suspect, would just reject Pius XIII as a heretic and thus refuse his dogmatic teaching. If this hypothetical Pius XIII came along and delcared BoD to be dogma, then I would immediately reject my former opinion and accept the teaching. Thus the difference between sedevacantism and sededoubtism. With straight sedevacantism established as permissible you couldn't have any a priori guarantee of the truth of any dogmatic papal teaching.
By the way, Sneaky, if you were to convince me that Suprema Haec represents true Catholic teaching, then I would immediately cease to be a Traditional Catholic and would accept Vatican II as substantially free form error. Every error and heresy that can be attributed the the V2 papal claimants can be traced back to and logically follows from the Suprema Haec ecclesiology.
For the sake of reasonableness, I doubt that any future pope will proclaim BoD to be "heretical." What is likely to happen is, it would be made clear what the Church teaches in this regard (which this pernicious letter does not do, even though the quote below says it does), such that no Catholic can henceforth accuse someone of "heresy" for saying that BoD isn't "dogma," as they're doing now.
BoD is a theological speculation for dreamers to muse over, is all, but it has a darker side. It has absolutely no practical application in the real world except to give a hypothetical platform for subtle denial of
EENS as the Church has always taught it.
The perennial teaching of the Church regarding
EENS has nothing to do with this pernicious private letter of 1949, BTW.
Here is a clip from a well-known commentary on the pernicious private letter between cardinals of 1949:
A year before the appearance of the Humani generis, the Supreme Sacred Congregation of the Holy Office sent to the Most Reverend Archbishop of Boston a letter containing explanations on the subject of the dogma that no one can be saved outside of the Catholic Church. This highly important docuмent was approved by Pope Pius XII. Despite the fact that it was sent prior to the issuance of the Humani generis, it was not published until two years after the publication of the encyclical. This Holy Office letter is the Suprema, haec sacra, one of the most important doctrinal statements which appeared during the reign of the late and beloved Sovereign Pontiff [Pope Pius XII].
This docuмent set forth clearly and in detail, and as the authentic teaching of the Holy See, the explanation of the dogma on the necessity of the Catholic Church for the attainment of eternal salvation which had long been presented as common teaching in the theological teaching on the Church itself.
The elements of the exposition contained in the Suprema, haec sacra had, of course, long since been presented to the faithful in previous authoritative statements of the Church's magisterium [sic]. The entire doctrine, however, had never before been synthesized and set forth as clearly and in such scientifically complete detail in any previous docuмent.
It might be worth noting that while "despite the fact that it was sent prior to the issuance of the
Humani generis, it was not published until two years after the publication of the encyclical" (Aug. 12, 1950), it was
also not published until after the death of its author, Francesco Cardinal Marchetti-Selvaggiani (d. Jan. 1951).
Why do you suppose they waited until he had died before publishing it? For example, one of the obvious consequences of such a plan would be that nobody would be able to ask the author any questions about its composition or purpose, since he was dead.
Furthermore, it is noteworthy that this pernicious private letter between cardinals was given a Denzinger number (801) and insidiously inserted into the next edition of Denzinger (which is not an official publication of the Church) by none other than the disreputable Karl Rahner, as if it were some "authentic teaching of the Holy See" (as said in the above quote), even though it doesn't have any AAS number (which all authentic teachings of the Holy See have).
The point is, even though this pernicious private letter between cardinals was in fact no "authentic teaching of the Holy See," it was GIVEN THE APPEARANCE OF HAVING SUCH AUTHORITY, by the likes of Karl Rahner, an acknowledged heretic and Modernist, who had been provided a position of authority in the Church by none other than "our beloved sovereign Pontiff," Pope Pius XII.* And furthermore, such lap-dog lemmings as the quoted author above, would henceforth scamper to the front lines of public awareness via such publications as
Homiletic and Pastoral Review to attempt to defend the indefensible, just like sedevacantists do today (read: sedes like 'Sneakyticks').
*Note: this is the same beloved Pontiff who gave Annibale Bugnini his position of power
which would effect eventually the Newmass and the worldwide devastation of our beloved churches.