The failure of theologians and bishops, following the close of the Vatican Council in 1870, to properly accept and propagate the true meaning of infallibility as it was defined by the Council left Catholics without a sure guide following the death of Pope Pius XII. Many believed that documents of the Ordinary magisterium were not infallible or were less binding than “ex cathedra” pronouncements. One well-known British priest even openly taught this heresy. Using this reasoning, dissident Catholics then dismissed the Bull of Pope Paul IV and other papal documents that would have led them out of the darkness that was Vatican 2.
Most recently, this erroneous thinking has even been used to dismiss Pope Pius XII’s entirely orthodox teaching on the possible salvation of some of those who die without being members of the Church. It is time the true teachings of the Church on this matter were made known and the source of these errors exposed. Catholics must at some point realize fully and completely that the only reliable source of truth throughout the ages are the decrees of the Roman Pontiffs and the Ecumenical Councils, just as they are written. As Humani Generis itself states, the Teaching Authority of the Church alone can decide what belongs to the Deposit of Faith, and then only in that sense that has always been taught by the Church.
© Copyright 2019, T. Stanfill Benns (This text may be downloaded or printed out for private reading, but it may not be uploaded to another Internet site or published, electronically or otherwise, without express written permission from the author. All emphasis within quotes is the author’s unless indicated otherwise.)
His Holiness Pope Pius XII, August 12, 1950
(Encyclical Letter Concerning Some False Opinions Which Threaten to Undermine the Foundations of Catholic Doctrine)
- It is for this reason that divine revelation must be considered morally necessary so that those religious and moral truths which are not of their nature beyond the reach of reason in the present condition of the human race, may be known by all mean readily — with a firm certainty and with freedom from all error. 
- If anyone examines the state of affairs outside the Christian fold, he will easily discover the principle trends that not a few learned men are following. Some imprudently and indiscreetly hold that evolution, which has not been fully proved even in the domain of natural sciences, explains the origin of all things, and audaciously support the monistic and pantheistic opinion that the world is in continual evolution. Communists gladly subscribe to this opinion so that, when the souls of men have been deprived of every idea of a personal God, they may the more efficaciously defend and propagate their dialectical materialism.
- Another danger is perceived which is all the more serious because it is more concealed beneath the mask of virtue. There are many who, deploring disagreement among men and intellectual confusion, through an imprudent zeal for souls, are urged by a great and ardent desire to do away with the barrier that divides good and honest men; these advocate an “eirenism” setting aside the questions which divide men, they aim not only at joining forces to repel the attacks of atheism, but also at reconciling things opposed to one another in the field of dogma.
- Now if these only aimed at adapting ecclesiastical teaching and methods to modern conditions and requirements, through the introduction of some new explanations, there would be scarcely any reason for alarm. But some through enthusiasm for an imprudent “eirenicism” seem to consider as an obstacle to the restoration of fraternal union, things founded on the laws and principles given by Christ and likewise on institutions founded by Him, or which are the defense and support of the integrity of the faith, and the removal of which would bring about the union of all, but only to their destruction.
- In theology, some want to reduce to a minimum the meaning of dogmas; and to free dogma itself from terminology long established in the Church and from philosophical concepts held by Catholic teachers, to bring about a return in the explanation of Catholic doctrine to the way of speaking used in Holy Scripture and by the Fathers of the Church…
- It is evident from what We have already said, that such tentatives not only lead to what they call dogmatic relativism, but that they actually contain it. The contempt of doctrine commonly taught and of the terms in which it is expressed strongly favor
- The contempt for terms and notions habitually used by scholastic theologians leads of itself to the weakening of what they call speculative theology, a discipline which these men consider devoid of true certitude because it is based on theological reasoning.
- Unfortunately these advocates of novelty easily pass from despising scholastic theology to the neglect of and even contempt for the Teaching Authority of the Church itself, which gives such authoritative approval to scholastic theology. This Teaching Authority is represented by them as a hindrance to progress and an obstacle in the way of science. Some non-Catholics consider it as an unjust restraint preventing some more qualified theologians from reforming their subject. And although this sacred Office of Teacher in matters of faith and morals must be the proximate and universal criterion of truth for all theologians, since to it has been entrusted by Christ Our Lord the whole deposit of faith — Sacred Scripture and Divine Tradition — to be preserved, guarded and interpreted, still the duty that is incumbent on the faithful to flee also those errors which more or less approach heresy, and accordingly “to keep also the constitutions and decrees by which such evil opinions are proscribed and forbidden by the Holy See,”  is sometimes as little known as if it did not
- Although these things seem well said, still they are not free form error. It is true that Popes generally leave theologians free in those matters which are disputed in various ways by men of very high authority in this field; but history teaches that many matters that formerly were open to discussion, no longer now admit of
- Nor must it be thought that what is expounded in Encyclical Letters does not of itself demand consent, since in writing such Letters the Popes do not exercise the supreme power of their Teaching Authority. For these matters are taught with the ordinary teaching authority, of which it is true to say: “He who hears you Hears Me,”:  and generally what is expounded and inculcated in Encyclical Letters already for other reasons appertains to Catholic doctrine. But if the Supreme Pontiffs in their official documents purposely pass judgment on a matter up to that time under dispute, it is obvious that that matter, according to the mind and will of the Pontiffs, cannot be any longer considered a question open to discussion among
- This deposit of faith our Divine Redeemer has given for authentic interpretation not to each of the faithful, not even to theologians, but only to the Teaching Authority of the Church. But if the Church does exercise this function of teaching, as she OFTEN has through the centuries, either in the ordinary or in the extraordinary way, it is clear how false is a procedure which would attempt to explain what is clear by means of what is obscure. Indeed, the very opposite procedure must be used. Hence Our Predecessor of immortal memory, Pius IX, teaching that the most noble office of theology is to show how a doctrine defined by the Church is contained in the sources of revelation, added these words, and with very good reason: “in that sense in which it has been defined by the Church.”
- Some say they are not bound by the doctrine, explained in Our Encyclical Letter of a few years ago, and based on the Sources of Revelation, which teaches that the Mystical Body of Christ and the Roman Catholic Church are one and the same thing.
- If one considers all this well, he will easily see why the Church demands that future priests be instructed in philosophy “according to the method, doctrine, and principles of the Angelic Doctor,”  since, as we well know from the experience of centuries, the method of Aquinas is singularly preeminent both of teaching students and for bringing truth to light; his doctrine is in harmony with Divine Revelation, and is most effective both for safeguarding the foundation of the faith and for reaping, safely and usefully, the fruits of sound progress. 
- While scorning our philosophy, they extol other philosophies of all kinds, ancient and modern, oriental and occidental, by which they seem to imply that any kind of philosophy or theory, with a few additions and corrections if need be, can be reconciled with Catholic dogma.
- It is not surprising that these new opinions endanger the two philosophical sciences which by their very nature are closely connected with the doctrine of faith, that is, theodicy and ethics; they hold that the function of these two sciences is not to prove with certitude anything about God or any other transcendental being, but rather to show that the truths which faith teaches about a personal God and about His precepts, are perfectly consistent with the necessities of life and are therefore to be accepted by all, in order to avoid despair and to attain eternal salvation. All these opinions and affirmations are openly contrary to the documents of Our Predecessors Leo XIII and Pius X, and cannot be reconciled with the decrees of the Vatican Council. 
- It remains for Us now to speak about those questions which, although they pertain to the positive sciences, are nevertheless more or less connected with the truths of the Christian fait in fact, not a few insistently demand that the Catholic religion take these sciences into account as much as possible. This certainly would be praiseworthy in the case of clearly proved facts; but caution must be used when there is rather question of hypotheses, having some sort of scientific foundation, in which the doctrine contained in Sacred Scripture or in Tradition is involved. If such conjectural opinions are directly or indirectly opposed to the doctrine revealed by God, then the demand that they be recognized can in no way be admitted.
- When, however, there is question of another conjectural opinion, namely polygenism, the children of the Church by no means enjoy such liberty.
- When, however, there is question of another conjectural opinion, namely polygenism, the children of the Church by no means enjoy such liberty. Let the teachers in ecclesiastical institutions be aware that they cannot with tranquil conscience exercise the office of teaching entrusted to them, unless in the instruction of their students they religiously accept and exactly observe the norms which We have ordained.
- Let them strive with every force and effort to further the progress of the sciences which they teach; but let them also be careful not to transgress the limits which We have established for the protection of the truth of Catholic faith and doctrine. With regard to new questions, which modern culture and progress have brought to the foreground, let them engage in most careful research, but with the necessary prudence and caution; finally, let them not think, indulging in a false “eirenicism,” that the dissident and the erring can happily be brought back to the bosom of the Church, if the whole truth found in the Church is not sincerely taught to all without corruption or
(For full text, see http://www.newadvent.org/library/docs_pi12hg.htm)