1. When we trace the theological note pre-Vatican II theologians assign to the proposition "A Universally Accepted Pope is certainly the legitimately elected Supreme Pastor of the Catholic Church", it is almost always assigned a theological note so high, e.g. doctrina catholica, facta dogmatica, even de fide or proxima fidei sometimes, that it clearly follows that it is not licit for an informed Catholic - completely aware or thoroughly instructed in this teaching, its theological basis and the authorities who have explained its theological note - to doubt or deny it. This has been docuмented recently with many citations in SSPX-endorsed "True or False Pope" by S&S. See for e.g. http://www.trueorfalsepope.com/p/peaceful-and-universal-acceptance-of.html

But when on the contrary we trace the history of the awareness of "Universal Acceptance" as a Catholic Doctrine in the Traditional Movement, the history is a little less clear - or rather, it is very unclear. What is certain is that Fr. Boulet, in 2004, makes reference to Universal Acceptance, but only very briefly, in disregarding the so-called Siri Thesis. "Finally, Cardinal Siri died in 1989. But, the most important reason why we must discard the "Pope Siri" theory is the fundamental principle that a peaceful acceptance of a pope by the Universal Church is the infallible sign and effect of a valid election. All theologians agree on that point. Cardinal Billot says: "God may allow that a vacancy of the Apostolic See last for a while. He may also permit that some doubt be risen about the legitimacy of such or such election. However, God will never allow the whole Church to recognize as Pontiff someone who is not really and lawfully.  Thus, as long as a pope is accepted by the Church, and united with her like the head is united to the body, one can no longer raise any doubt about a possible defective election… For the universal acceptance of the Church heals in the root any vitiated election." From a 2004 Article: http://fsspx.com/Communicantes/Dec2004/Is_That_Chair_Vacant.htm

2. Whether Archbishop Lefebvre was aware of the theological note assigned by Billot, Van Noort et al is another question, because the matter had not yet been very deeply studied in the 60s and 70s, when the question was just being raised. Archbishop Lefebvre commissioned Society Theologians to investigate the matter. A study of Xavier Da Silveira makes reference to it in principle, yet not as something absolutely certain, but also seems to discount its application to the post-Conciliar Popes at the same time. So perhaps +ABL's views were largely informed by Da Silveira's study. What +ABL's precise views were, and whether they were always consistently held, has been continuously disputed. +ABL did make reference in 1979 to something very much like UA, i.e. Convalidation by unanimous acceptance. "Does not the exclusion of the cardinals of over eighty years of ages, and the secret meetings which preceded and prepared the last two Conclaves, render them invalid? Invalid: no, that is saying too much. Doubtful at the time: perhaps. But in any case, the subsequent unanimous acceptance of the election by the Cardinals and the Roman clergy suffices to validate it. That is the teaching of the theologians." But it is unclear and uncertain if this was considered theological opinion or a Catholic doctrine.

Anyway, the question today is independent of +ABL. Pope Benedict XVI and Pope Francis were elected in 2005 and 2013, 14 and 22 years respectively after +ABL's holy death. The questions before us today are, where is the Teaching Church? Does the Hierarchy recognize the Pope? If the answer to those questions suggests the Catholic Bishops of today recognize the Pope, then he is surely Pope. It may be, some time in the future, that the Pope, losing universal acceptance, also falls from the pontificate. This also complicates the fact for those who are Bishops - like +ABL was - since it may be up to them to pass judgment. But, that is not for us.

Thoughts? Let's take just one citation from the first link to see what note theologians assign to the proposition,

"Meantime, notice that the Church possesses infallibility not only when she is defining some matters in solemn fashion, but also when she is exercising the full weight of her authority through her ordinary and universal teaching. Consequently, we must hold with an absolute assent, which we call ‘ecclesiastical faith,’ the following theological truths: (a) those which the Magisterium has infallibly defined in solemn fashion; (b) those which the ordinary magisterium dispersed throughout the world unmistakably proposes to its members as something to be held (tenendas). So, for example, one must give an absolute assent to the proposition: ‘Pius XII is [present tense] the legitimate successor of St. Peter’; similarly … one must give an absolute assent to the proposition: ‘Pius XII possesses the primacy of jurisdiction over the entire Church.’ For — skipping the question of how it begins to be proven infallibly for the first time that this individual was legitimately elected to take St. Peter’s place — when someone has been constantly acting as Pope and has theoretically and practically been recognized as such by the bishops and by the universal Church, it is clear that the ordinary and universal magisterium is giving an utterly clear-cut witness to the legitimacy of his succession [to St. Peter - Xavier]." (Sources of Revelation, p. 265)

Heh. If we have indeed discussed it precisely a dozen times, then it has also been exactly a dozen times that you have evaded both questions Q1: Where is the Teaching Church today? Q2: Does the Teaching Church recognize the Pope? The answer to those questions is the first answer to this crisis. 

I consider His Excellency Bishop Williamson to be a Catholic Bishop, and if I spoke to H.E., I would kneel, kiss his hand, and address him as "Your Excellency ... " before asking my question, just as I do to my own SSPX Bishops and Priests. However, that's irrelevant to the docuмented fact that the entire Society of St. Pius X, as of 2014 (I think it was), has officially endorsed the dogmatic fact teaching by endorsing TOFP.

I've clearly said no one is a heretic if the theological note has not been explained to him - which, according to you, has now been explaned to you "about a dozens times already". So, it is calumny and slander - par for the course from you - to accuse me of accusing saintly +ABL or +BW of being heretics. I have never done that. ever. 

Yes, I would discuss it reverently with +BW, in the manner I explained, but not polemically as you seem to wish. I believe Sean is doing that also. Anyway, that's your internal Resistance issue. For me, my hope is still that a deeper understanding and common awareness of this teaching among both Society and Resistance can lead in the future to a happy SSPX-Resistance reconciliation or re-union. Because, if the Pope is the Pope, then to obtain Ordinary Jurisdiction from him, as the SSPX Bishops obtained after the Year of Mercy, as Bishop Fellay has explained, is something not only not evil, but even something positively good - their right in fact, an injustice now corrected.

I raised the Universal Acceptance issue with Rev. Father Cekada in 2012 on Ignis Ardens, even before Siscoe (who PM'ed me to ask for a source I cited) and Salza had published their book. Father Cekada's answer to the text of Billot I cited was literally shocking to me, it was something like (IA is down now) "As regards Billot et al, as far as I know, dogmatic fact teaching applies only to non-heretics" or something close to that. Rev. Father Cekada said he would more closely study the matter and get back to me on it. I have no doubt that Fr. Cekada is a good man and would make a valuable addition to the team - if only we Traditional Catholics were all united, we would have so much more clout in demanding the Restoration of Tradition. I can't wait for doctrinal discussions round #2 to begin, where the Society Theologians can begin again presenting the best possible case for the Catholic Faith and Catholic Tradition that human reason aided by divine Faith and supernatural grace can offer. Fr. Cekada's detailed studies on the new liturgy for e.g. still have a lot of value, and are taken extremely seriously even by some mainsteam non-sedevacantist Catholic scholars.

Forlorn, if you scroll down and read the OP article, many of the objections are answered including the one on the "second man" scenario. The historical example of Pope Innocent II is also explained vis-a-vis anti-pope Anacletus II. At any rate, those were contested elections, while no competing candidate (e.g. Pope Benedict XVI, who has stated numerous times he recognizes Pope Francis as his Pope) is contesting the election of Pope Francis today. "Anacletus II’s election was not uncontested (‘peaceful’), nor was he ever ‘universally accepted’ as Pope by the Church.  “The long version at Newadvent.org” refers to his election as “the contested papal election of the year 1130.”[16] The reason it was contested is because it took place 3 hours after the election of the true Pope Innocent II – who was proclaimed to be the true Pope by three synods held later same year."

As we learn from the text of His Eminence Cardinal Journet, whom Saintly Archbishop Lefebvre called "a deep thinker and a great theologian", the election of the Pope being in some way contested (by an opposing candidate) is essential to there not being UA. "[T]he peaceful acceptance of the universal Church given to an elect, as to a head to whom it submits, is an act in which the Church engages herself and her fate. It is therefore an act in itself infallible and is immediately recognizable as such. (Consequently, and mediately, it will appear that all conditions prerequisite to the validity of the election have been fulfilled. "Acceptance by the Church operates either negatively, when the election is not at once contested; or positively, when the election is first accepted by those present and then gradually by the rest.[4] The Church has the right to elect the Pope, and therefore the right to certain knowledge as to who is elected."[5]

Salsa and Disco believe that the Conciliar Church is the Catholic Church.  That's why all their arguments are completely wrong.  If they understood that only the clergy who have been ordained and consecrated in the traditional Roman rite and who continue to teach traditional Catholic doctrine are the true clergy of the Catholic Church then they would see that there is no UPA of an obviously heretical pope.  When you believe that the Conciliar Church is the Catholic Church you run into big problems with the marks of the Church.  The Conciliar Church is not one, holy, catholic and apostolic.  If it was, there would be no SSPX, FSSP, nor sede vacantists.  You're trying to put lipstick on a pig.  The Conciliar Church is a disgusting pig.  No morally sound person should have anything to do with that heretical, perverted disgusting Fag Mafia-led crime syndicate.

Stubbs, we have Pope Pius XII and Pope Benedict XIV, if we want Magisterial endorsements of the principle, who apply something very much like Universal or Unanimous (I think that's a distinction without a difference) Acceptance. According to Pope Pius XII, in the infallible Dogmatic Bull MUNIFICENTISSIMUS DEUS, the universal agreement of the episcopate that the Assumption was dogmatically definable was already an infallibly certain proof that it was a revealed Truth, an example of the Ordinary and Universal Magisterium passing judgment on the question. The exact words of His Holiness are, "those whom "the Holy Spirit has placed as bishops to rule the Church of God"(4) gave an almost unanimous affirmative response to both these questions. This "outstanding agreement of the Catholic prelates and the faithful,"(5) affirming that the bodily Assumption of God's Mother into heaven can be defined as a dogma of faith, since it shows us the concordant teaching of the Church's ordinary doctrinal authority and the concordant faith of the Christian people which the same doctrinal authority sustains and directs, thus by itself and in an entirely certain and infallible way, manifests this privilege as a truth revealed by God ... Thus, from the universal agreement of the Church's ordinary teaching authority we have a certain and firm proof" (para 12). Similarly, Pope Benedict XIV, as we know, said we cannot separate from communion by the Pope recognized by all, for e.g. by dropping his name from the Canon of the Mass, and choosing be non-una-cuм-the Pope. That implies the Pope so recognized is truly Pope.

Clemens Maria, ok, your view is that "unanimous acceptance" would constitute Papal legitimacy as a dogmatic fact in principle, but you deny or doubt whether it actually applies to the post-Conciliar Pontiffs. Is that accurate representation of your position? You go on to state that you consider the Hierarchy to consist only of Traditional Catholic Bishops, excluding all mainstream Bishops. But, as you know, the problem with that is, we consult almost any pre-Vatican II definition, and they will tell us, one of the requirements to be a member of the Teaching Church is to have been appointed by the Pope. Without that, a Bishop is called an auxiliary Bishop at most, or sometimes an episcopus vagans if he has no diocese. So, how do you square that with your understanding of where the Hierarchy is?

Take one example from Pope Pius IX, Quartus Supra: The Pope is here speaking of an Eastern rite Patriarch, in whose election the Pontiffs give the right to Bishops to elect their Patriarch, but only as a designate. Now, the Pope says, until the Pope makes the appointment by confirming the chosen candidate, the episcopal see or patriarchal throne remains vacant. Doesn't it seem to follow from this that a vagrant Bishop can obtain the power of jurisdiction over a diocese or a see only after some Pope appoints him to it? See para 24, "We commanded that a synod composed exclusively of bishops elect the patriarch. However, We forbade the man elected to be enthroned until he received a letter of confirmation from the Apostolic See ... When this is done, the Roman pontiff will choose one of those recommended and put him in charge of the vacant see". From: https://www.papalencyclicals.net/pius09/p9quartu.htm

God bless.  

You go on to state that you consider the Hierarchy to consist only of Traditional Catholic Bishops, excluding all mainstream Bishops. But, as you know, the problem with that is, we consult almost any pre-Vatican II definition, and they will tell us, one of the requirements to be a member of the Teaching Church is to have been appointed by the Pope. Without that, a Bishop is called an auxiliary Bishop at most, or sometimes an episcopus vagans if he has no diocese. So, how do you square that with your understanding of where the Hierarchy is?

I don’t disagree with anything you have explicitly stated in your comments.  But I do disagree with your unstated presupposition that there must be at least one member of the Teaching Church living at every moment in time because otherwise the Church will defect.
As evidence against that view I recommend you read Van Noort’s ecclesiology book.  He was making the point that the majority opinion is that the Roman See will never defect.  He explicitly contemplated the possibility that all the other sees could be simultaneously wiped out in a nuclear war.  In that case, how many ordinaries exist?  Exactly one, correct?  The Roman Pontiff.  What happens when he dies?  How many ordinaries are there?  None!  Does the Roman See defect during a vacancy?  No!  All the theologians are agreed on that.  If the Roman See cannot defect during a vacancy then neither can the Church as a whole defect during a vacancy.  So a lack of ordinaries does not constitute a defection.  Please cite a source for your belief that there must be at least one living ordinary at every moment in time.

This is a good point.  UA does not cause a legitimate papacy, but it can be considered a criterion for the subjective certainty regarding it.

I think that there's room for the traditional quoad se and quoad nos distinction when applied to legitimate papacy.

I'll think some more on this later.

UA is explained as "an infallible sign" that the man is pope.  It doesn't make him the pope (quoad se), but infallibly proves that he is pope (quoad nos).    

If a pope has not been peacefully accepted, he may still be the true pope (quoad se), but his legitimacy as Pope will not be infallibly certain (quoad nos).

But we have cases that have been brought forth of a legitimately-elected Pope who was hauled off and jailed, and then another was elected in his place and Universally Accepted.

QUOAD SE, the originally-elected Pope was still the legitimate pope, despite it not being manifest QUOAD NOS.

I've looked into those cases and the history is sketchy, to say the least.  From what I've found, the only time another pope was peacefully accepted after the previous pope was illegally deposed, is when the original pope submitted to the illegal deposition, which the theologians said was equivalent to a resignation.