Yes, very interesting, a subject being discussed in the laterst chapter of THE EARTHMOVERS in the resistance movements slot.
Perhaps no other matter in Catholic history has come under the 'infallible' microscope like the anti-Copernican decree of Pope Paul V in 1616. If ever the subject matter of infallibility has been taken apart like a motor-engine into all its bits they are to be found in the 350 year-old Galileo affair. Here is the first case where all the contradictions to infallibility came to the fore. Indeed the rejection of popes in 1741, 1820 and 1835 of the 1616 decree led some to reject the dogma of infallibility of Vatican I as already proven false. one of these was a Fr Roberts who explained his position like this:
` ‘If, then, the Pope said in effect that heliocentrism was a heresy, he said in effect that it was not only de fide, but de fide Catholicâ, that it was false; that it was not only de fide, but de fide Catholicâ, that its contradictory was true. In what capacity he spoke, and whether he meant what he said, are further questions, but it is a great point to have it conceded that he did in effect declare heliocentrism to be a “heresy.” But we also learn from the statement of a Pontifical Congregation [1633 and 1820] that the utterance was a definition, i.e. a final authoritative judgment. We are brought, therefore, to the conclusion that the Pope did in fact publish, through the Congregation of the Index, a definition of faith. Now, suppose for a moment that he did so ex cathedrâ, would it follow that the definition was of the same kind as that by which Pius IX decided the question of the Immaculate Conception? And ought it to have been promulgated with like emphasis and solemnity? Assuredly not. The Immaculate Conception definition of the Bull “Ineffabilis” was put forward to make that of Catholic faith which confessedly was not so before. Up to the 8th of December 1854 it was, by the force of Bulls that had not been formally revoked, excommunication to call the denial of the doctrine of the Immaculate Conception heresy, or even, if I mistake not, to say that those who impugned it were guilty of grave sin. Since that date, according to the Bull, any one who ventures to think that the doctrine has not been revealed by God, ipso facto, makes shipwreck of his faith, and cuts himself off from the unity of the Church. Clearly the definition was of the nature of a new doctrinal law, and therefore needed a promulgation that would challenge the attention of all Christians. But not every Pontifical definition ex cathedrâ ascribing heresy or repugnancy to Scripture to dissentients is a definition of faith in this sense. By far the greater number are issued, not to generate any fresh obligation of faith, but to protect and vindicate one that already exists; and to this class obviously belong ex cathedrâ censures of books, and propositions, defined as heretical. The mode of publishing these judgments will vary of course with circuмstances, but from their nature there is no reason for their being put forward with any greater emphasis and solemnity than the evil to be met requires. Why, then, should they not occasionally be issued through one of the Congregations the Pope has erected to assist him in discharging his functions as guardian of the faith? And why should such a mode of publication prejudice their infallibility, if they are certainly Papal decisions, and are known to be such?’ ---- Rev. William W. Roberts: The Pontifical Decrees against the Earth’s Movement and the Ultramontane Defence of them, Parker and Company, London, 1870, revised 1885, p.22.
Now here is my understanding of infallibility. An 'extraordinary' infallibility is used to define a NEW DOGMA.
The ordinary magisterium is used to protect and judge on matters that are already matters of faith and morals.
‘The Roman Pontiffs, moreover, according to the condition of the times and affairs advised, sometimes by calling ecuмenical councils… sometimes by particular synods, sometimes by employing other helps which divine providence supplied, have defined that those matters must be held which with God’s help they have recognised as in agreement with Sacred Scripture and apostolic tradition. For, the Holy Spirit was not promised to the successors of Peter that by His revelation they might disclose new doctrine, but that by His help they might guard sacredly the revelation transmitted through the apostles and the deposit of faith, and might forcefully set it out…’ --- Vatican I (1869-1870) (Denz. 1836.)
Vatican II popes therefor cannot use their infallible perogative to deny previous teachings.