RESPONSE TO MISCELLANEOUS OBJECTIONS & QUESTIONS:
1) To the objection that Cardinal Journet's support of what Bellarmine lists as"Opinion No. 4" on the question of deposing a heretic pope proves that that opinion was not universally abandoned; I ANSWER: One lone dissident voice against the dogma of the primacy does not diminish the moral unanimity of theologians and canonists that has existed since the late 19th Century on this point.
What about what these theologians wrote?
Van Noort, Christ’s Church (1957): “with regard to the pope when he is not speaking ex cathedra. All theologians admit that the pope can make a mistake in matters of faith and morals when so speaking: either by proposing a false opinion in a matter not yet defined, or by innocently differing from some doctrine already defined. Theologians disagree, however, over the question of whether the pope can become a formal heretic by stubbornly clinging to an error in a matter already defined. The more probable and respectful opinion, followed by Suarez, Bellarmine and many others, hold that just as God has not till this day ever permitted such a thing to happen, so too he will never permit a pope to become a formal and public heretic. Still, some competent theologians do concede that the pope when not speaking ex cathedra could fall into formal heresy. They add that should such a case of public papal heresy occur, the pope, either by the very deed itself or at least by a subsequent decision of an ecuмenical council, would by divine law forfeit his jurisdiction.” (Van Noort, Christ’s Church, 1957, No. 181)
Father Ghirlanda, S.J., former rector of the Gregorian University (2013): “The vacancy of the Roman See occurs in case of the cessation of the office on the part of the Roman Pontiff, which happens for four reasons: 1) Death, 2) Sure and perpetual insanity or complete mental infirmity; 3) Notorious apostasy, heresy, schism; 4) Resignation. In the first case, the Apostolic See is vacant from the moment of death of the Roman Pontiff; in the second and in the third from the moment of the declaration on the part of the cardinals; in the fourth from the moment of the renunciation. There is the case, admitted by doctrine, of notorious apostasy, heresy and schism, into which the Roman Pontiff could fall, but as a ‘private doctor,’ that does not demand the assent of the faithful … However, in such cases, because ‘the first see is judged by no one’ (Canon 1404) no one could depose the Roman Pontiff, but only a declaration of the fact would be had, which would have to be done by the Cardinals, at least of those present in Rome.” (Gianfranco Ghirlanda, Cessazione dall’ufficio di Romano Pontefice, "La Civiltà Cattolica" q. n 3905 March, 2, 2013, p. 445)
Elements of Ecclesiastical Law (1881): “Question: Is a Pope who falls into heresy deprived, ipso jure, of the Pontificate? “Answer: There are two opinions: one holds that he is by virtue of divine appointment, divested ipso facto, of the Pontificate; the other, that he is, jure divino, only removable. Both opinions agree that he must at least be declared guilty of heresy by the church, i.e., by an ecuмenical council or the College of Cardinals. The question is hypothetical rather than practical”. (Smith, Sebastian B. Elements of Ecclesiastical Law (revised third edition), New York: Benzinger Brothers, 1881)
Tanquerey (1897): “During the Vatican Council the bishop of Brexit [Vincent Gasser, spokesman for the Deputation de Fide] took the occasion to addressed the theological debate about whether a Pope, as a private person, can fall into heresy, by willfully and persistently adhering to an error against the faith. All concede that he can err against the faith due to ignorance, but many believe Providence will prevent him from erring pertinaciously and becoming a true heretic. (…) If it did to happen that the Pope fell into pertinacious heresy, he would either be ipso facto be deprived of the Pontificate, or the body of bishops could depose him, as in the case of doubtful pope: for in this extraordinary case, the authority passes (delolvitur) to the episcopal body.” (Tanquerey, Synopsis theologiae dogmaticae Fundamentalis, 1897, No. 180, f. 3. p. 465