During Pope Francis’ return flight from Canada, a journalist asked him about the possibility of a development in the Catholic Church’s teaching on contraception.
The pontiff replied:
This is something very timely. But know that dogma, morality, is always on a path of development but always developing in the same direction. To use something that is clear — I think I’ve said it other times here — for the theological development of a moral or dogmatic issue, there is a rule that is very clear and illuminating. It’s more or less what [St.] Vincent of Lérins did in the 10th century. He says that true doctrine, in order to go forward, to develop, must not be quiet; it develops “ut annis consolidetur, dilatetur tempore, sublimetur aetate [that it may be consolidated by the years, dilated by time, elevated by age].” That is, it is consolidated over time; it expands and consolidates and becomes always more solid, but always progressing.
So the pope talked a lot about doctrinal development. But he stipulates that it must always be “in the same direction.” What, precisely, does this mean? It may seem ambiguous at first blush, so let’s flesh out the idea the pontiff appears to be referencing.
First of all, I’ll give a disclaimer: Regarding birth control, the Catechism of the Catholic Church states very explicitly that “legitimate intentions on the part of the spouses do not justify recourse to morally unacceptable means (for example, direct sterilization or contraception).” Clear teaching on the immorality of contraception also came from Pope St. Paul VI in Humanae Vitae and Pope Pius XI in Casti Connubii.
Pope Pius XI
Now, back to this talk of “development.” The Magisterium of Holy Mother Church has always “developed” only in the sense of making it clearer, more intelligible and more explicit.
For example, Pope St. John Paul II made it clear and explicit that the ordination of women to the priesthood is impossible.
Saint Vincent notably distinguished development from alteration. Development means that each thing expands but remains itself, while alteration means that a thing is changed from one thing into another.
So development can happen but alteration cannot.
Consider an analogy: You might change with the passing of the years — growing taller, getting wrinkles, etc. — but you always remain the same person. There is a great difference between the flowering of childhood and the maturity of old age, but those who become old are the very same people who were once young.
Development means Church teaching remains the same, though it may look a bit different than it did when it was “younger,” so to speak.
Alteration, on the other hand, would disfigure the Church and change doctrine to be something completely different. It would be a contradiction, as it would mean some eternal truth Holy Mother Church affirmed in one era is suddenly false in the next.
With that in mind, Church leaders have often condemned certain novel ideas because they contradict Catholicism. For instance, Pope Pius IX wrote the Syllabus of Errors, an appendix to his encyclical letter, Quanta Cura. Both were promulgated on Dec. 8, 1864.
The syllabus is a long list of condemned errors, a catalog of various statements that Catholics should reject. It’s a highly recommended read, as many of the errors it enumerates are still encountered today.