Humanae Vitae is online at the Vatican site, and the text highlighted below is © Copyright – Libreria Editrice Vaticana. If HV 9 seemed sound, if somewhat incomplete, some Catholics might find this section a bit more problematic. Let’s read carefully, ponder, then discuss:
10. Married love, therefore, requires of husband and wife the full awareness of their obligations in the matter of responsible parenthood, which today, rightly enough, is much insisted upon, but which at the same time should be rightly understood. Thus, we do well to consider responsible parenthood in the light of its varied legitimate and interrelated aspects. With regard to the biological processes, responsible parenthood means an awareness of, and respect for, their proper functions. In the procreative faculty the human mind discerns biological laws that apply to the human person. (See St. Thomas, Summa Theologiae, I-II, q. 94, art. 2)
So far, so good. Indeed, parenting children can be complex, and couples may find conflict in important aspects.
With regard to innate (human) drives and emotions, responsible parenthood means that (human) reason and will must exert control over them.
I think caution of (human) drives is well-considered. We are not animals, after all, and enslaved to instinct without will. However, the emotional lives of human beings are more advanced than all or nearly all of the natural world. The human affect is not something so easily dismissed as illogical or something wild or in need of being controlled. Sometimes, it is human intelligence and cleverness that need to be tempered, not the feelings. Inevitably, human emotions are entwined with the care of spouse and children. I do not think they can be as easily dismissed as Pope Paul attempts here.
With regard to physical, economic, psychological and social conditions, responsible parenthood is exercised by those who prudently and generously decide to have more children, and by those who, for serious reasons and with due respect to moral precepts, decide not to have additional children for either a certain or an indefinite period of time.
Pope Paul makes an important point here: morality is not subjective, and a “right,” well-formed conscience is vital to tackle conflicting issues here. One cannot dive into marriage and family on autopilot. The issues must be engaged, wrestled with, and often will involve a genuine struggle. Sometimes the choice for more children is not driven by prudence or generosity, but by narcissism and selfishness. The interior of a person determines the true motivation, not the external appearances.
Responsible parenthood, as we use the term here, has one further essential aspect of paramount importance. It concerns the objective moral order which was established by God, and of which a right conscience is the true interpreter. In a word, the exercise of responsible parenthood requires that husband and wife, keeping a right order of priorities, recognize their own duties toward God, themselves, their families and human society. From this it follows that they are not free to act as they choose in the service of transmitting life, as if it were wholly up to them to decide what is the right course to follow.
This will undoubtedly move against the grain of many individualistic westerners. But it is true: there are duties and responsibilities that inconvenience us. Best to admit it, find the grace in it, and accept it as a mutuality in a human society.
On the contrary, they are bound to ensure that what they do corresponds to the will of God the Creator. The very nature of marriage and its use makes His will clear, while the constant teaching of the Church spells it out. (See Gaudium et Spes 50-51)
You can access that reference on the Vatican site, or even here and here when we discussed nine years ago. (Has it been that long?)