“The ancient authors everywhere admitted the axiom, ‘A doubtful pope is no pope’ and applied it to solve the difficulties which arose from the Great Western Schism. Now this axiom could be understood in several ways. For instance, a ‘doubtful pope’ can be understood not negatively, but positively - i.e., when, after a diligent examination of the facts, competent men in the Catholic Church would pronounce: 'The validity of the canonical election of this Roman pontiff is uncertain’. Moreover, the words 'No pope' are not necessarily understood of a pope who has previously been received as certain and undoubted by the whole Church, but concerning whose election so many difficulties are subsequently brought to light that he becomes 'a doubtful pope' so that he would thereby forfeit the pontifical power already obtained. This understanding of the axiom concerning 'a doubtful pope' should be reproved because the whole Church cannot entirely fall away from a Roman pontiff who has been legitimately elected, on account of the unity promised to His Church by Christ.
“But the other part of this axiom could have the meaning that a Roman pontiff whose canonical election is uncertain and remains subject to positive and solid doubts after studious examination, absolutely never did acquire also the papal jurisdiction from Christ the Lord. For this reason the bishops gathered together in a general council, in the event that they subject to examination a doubtful case of this kind, do not pronounce judgement on a true pope, since the person in question lacks the papal jurisdiction. Now if the axiom be understood in this last sense, the doctrine which it contains is entirely sound.
“Indeed this is what is deduced in the first place from the very nature of jurisdiction. For jurisdiction is essentially a relation between a superior who has the right to obedience and a subject who has the duty of obeying. Now when one of the parties to this relationship is wanting, the other necessarily ceases to exist also, as is plain from the nature of the relationship. However, if a pope is truly and permanently doubtful, the duty of obedience cannot exist towards him on the part of any subject. For the law, 'Obedience is owed to the legitimately-elected successor of St. Peter,' does not oblige if it is doubtful; and it most certainly is doubtful if the law has been doubtfully promulgated, for laws are instituted when they are promulgated, and without sufficient promulgation they lack a constitutive part, or essential condition. But if the fact of the legitimate election of a particular successor of St. Peter is only doubtfully demonstrated, the promulgation is doubtful; hence that law is not duly and objectively constituted of its necessary parts, and it remains truly doubtful and therefore cannot impose any obligation. Indeed it would be rash to obey such a man who had not proved his title in law. Nor could appeal be made to the principle of possession, for the case in question is that of a Roman pontiff who is not yet in peaceful possession. Consequently in such a person there would be no right of command - i.e. he would lack papal jurisdiction.
"The same conclusion is confirmed on the basis of the visibility of the Church. For the visibility of the Church consists in the fact that she possesses such signs and identifying marks that, when moral diligence is used, she can be recognized and discerned, especially on the part of her legitimate officers. But in the supposition we are considering, the pope cannot be found even after diligent examination. The conclusion is therefore correct that such a doubtful pope is not the proper head of the visible Church instituted by Christ. Nor is such a doubtful pope any less compatible with the unity of the Church, which would be in the highest degree prejudiced in the case of the body being perfectly separated from its head. For a doubtful pope has no right of commanding and therefore there is no obligation of obedience on the part of the faithful. Hence in such a case the head would be perfectly separated from the rest of the body of the Church. Cf. Suarez, De Fide, Disp.10, sect.6, n.4, 19." (Fr. Franz Xaver Wernz, Ius Decretalium ad Usum Praelectionum In Scholis Textus Canonicisive Juris Decretalium, , Tomus II, (Romae: De Propoganda Fide, 1898) Scholion 618). Ius Decretalium
“It happened a little afterward, that Sylverius died and Vigilius, who to that point sat in schism, now began to be the sole and legitimate Pontiff for certain through the confirmation and reception by the clergy and the Roman people.” (Bellarmine, De Romano Pontifice, IV, chapter 10)