From this article:
http://sspx.org/en/clear-ideas-popes-infallible-magisterium...Before you write it off because it comes from the sspx, just ignore that and concentrate on the quotes, which come from people who were talking BEFORE the sspx even existed...
The Ordinary Magisterium is ONLY infallible when it teaches "that which has always been taught". Christ gave the Apostles the "fullness of Truth" therefore, there is nothing new to add to the Faith. Therefore, the 1st century Christians had the full Faith, just like we do. This is why we can point to "what has always been taught" as a litmus test for the Faith - because it never changes!
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The point of the question
The infallible guarantee of divine assistance is not limited solely to the acts of the Solemn Magisterium; it also extends to the Ordinary Magisterium, although it does not cover and assure all the latter’s acts in the same way. (Fr. Labourdette, O.P.,
Revue Thomiste, 1950, p.38)
Thus, the assent due to the Ordinary Magisterium "
can range from simple respect right up to a true act of faith." (Archbishop Guerry,
La Doctrine Sociale de l’Eglise, Paris,
Bonne Presse, 1957, p.172). It is most important, therefore, to know precisely when the Roman pope’s Ordinary Magisterium is endowed with the charism of infallibility.
Since the pope alone possesses the same infallibility conferred by Jesus Christ upon his Church [
i.e., the pope plus the bishops in communion with him,
cf. Denzinger [Dz.]1839), we must conclude that only the pope, in his Ordinary Magisterium, is infallible in the same degree and under the same conditions as the Ordinary Magisterium of the Church is.
Thus the truth that is taught must be proposed as already defined, or as what has always been believed or accepted in the Church, or attested by the unanimous and constant agreement of theologians as being a Catholic truth [which is therefore] strictly obligatory for all the faithful." ("Infaillibilite du Pape", DTC, vol. VII, col. 1705)
This condition was recalled by Cardinal Felici in the context of
Humanae Vitae:
On this problem we must remember that a truth may be sure and certain, and hence it may be obligatory, even without the sanction of an ex cathedra definition. So it is with the encyclical Humanae Vitae, in which the pope, the supreme pontiff of the Church, utters a truth which has been constantly taught by the Church’s Magisterium and which accords with the precepts of Revelation." (L’Osservatore Romano, Oct. 19, 1968, p.3)
No one, in fact, can refuse to believe what has certainly been revealed by God. And it is not only those things that have been defined as such that have certainly been revealed by God; the latter also include whatever has been always and everywhere taught by the Church’s Ordinary Magisterium as having been revealed by God. More recently, Archbishop Bertone reminded us that the Ordinary Pontifical Magisterium can teach a doctrine as
definitive [emphasis in original] in virtue of the fact
that it has been constantly preserved and held by Tradition.
Such is the case with
Ordinatio Sacerdotalis when it repeats the invalidity of the priestly ordination of women, which has always been held by the Church with "
unanimity and stability" (
L’Osservatore Romano, Dec. 20, 1996).
Cardinal Siri, still speaking of
Humanae Vitae in the issue of the review
Renovatio to which we have referred, explains as follows:
The question, therefore, must be put objectively thus: given that [Humanae Vitae] is not an act of the Infallible Magisterium and that it therefore does not of itself provide the guarantee of ‘irreformability’ and certitude, would not its substance be nonetheless guaranteed by the Ordinary Magisterium under the conditions under which the Ordinary Magisterium is itself known to be infallible?"
After giving a summary of the Church’s continuous tradition on contraception, from the Didache to the encyclical
Casti Connubii of Pope Pius XI, Cardinal Siri concludes:
This encyclical recapitulated the ancient teaching and the habitual teaching of today. This means that we can say that the conditions for the Ordinary irreformable [i.e., infallible—Ed.] Magisterium were met. The period of widespread turbulence is a very recent fact and has nothing to do with the serene possession [of the Magisterium—Ed.] over many centuries." (Renovatio, op.cit.)
It is an error, therefore, to extend infallibility unconditionally to the whole of the Ordinary Magisterium of the pope, whether he is speaking urbi et orbi or just addressing pilgrims. It is true that the infallibility of the Extraordinary Magisterium is not enough for the Church; the Extraordinary Magisterium is a rare event, whereas "
faith needs infallibility and it needs it every day," as Cardinal Siri himself said (
Renovatio,
op.cit.). But Cardinal Siri is too good a theologian to forget that even the pope’s infallibility has conditions attached to it.
If the Ordinary Magisterium is to be infallible, it must be traditional (
cf. Salaverri,
loc. cit.).
If it breaks with Tradition, the Ordinary Magisterium cannot claim any infallibility. Here we see very clearly the very special nature of the Ordinary Infallible Magisterium, to which we must devote some attention.
The special nature of the Ordinary Infallible Magisterium
As we have seen, Cardinal Siri observes that the Humanae Vitae, even if it is not an act of the
ex cathedra Magisterium, would still furnish the guarantee of infallibility, not "of itself," but insofar as it recapitulates "
the ancient teaching and the habitual teaching of today" (
Renovatio,
op. cit.). In fact, in contrast to the Extraordinary Magisterium or the Solemn Judgment, the Ordinary Magisterium does not consist in an isolated proposition, pronouncing irrevocably on the Faith and containing its own guarantees of truth, but in a collection of acts which can concur in communicating a teaching.
This is the normal procedure by which Tradition, in the fullest sense of that term, is handed down;..." (Pope or Church?, op. cit. p.10)