Overpopulation has many different bits to talk about, but this article makes me want to focus on one, Contraception and Natural Family Planning.
One of the aspects of materialism is that we reduce our physical actions to meaninglessness. Outward actions become no indicator of interior intent. When our world is seen materialistically, there is no interior difference between the latest scientific form of birth control and the rhythm method, all that is different is the degree of effect. Nothing could be further from the truth.
Because the goal of Catholicism is communion, it should come as no surprise that the Church teachings on sex inside of marriage are based upon her understanding of communion. There are two basic and common approaches used by science to avoid pregnancy: separating spouses and destroying health.
Condoms, cervical caps, and so forth are all used to separate one spouse from another.
Not a good example of “sexy times”
By separating spouses, these methods betray the unity of the marital act. The subtext of the action is “I need my space; we can be intimate, but not wholly intimate”. Just as the sheets covering the heads in Magritte’s “The Lovers” betrays the intimacy of a kiss, so too do barrier methods betray the intimacy of sex. The canard is that Orthodox Jews can only have sex through a hole in a sheet, but the truth is that modern people have sex with a sheet covering the one bit that even in myths Orthodox Jews would leave uncovered. Irony abounds.
The common alternative science offers is the destruction of a healthy body part though methods like the pill, vasectomies, or tubal ligation. In these methods the spouse has part of their body destroyed or distorted. This is much like Body Integrity Identity Disorder, a.k.a. apotemnophilia. In this disease people don’t feel right unless they are not whole, so healthy body parts are sometimes removed to make the person feel better. In a similar way, healthy body parts are made to be unhealthy or removed so that pregnancy might not occur. The subtext of the action here is, “I love you, but not your fertile part”. A certain portion of the spouse must be done away with before sex can commence. The rejected bit removed or temporarily disabled so that the spouse may be loved. This is not love, since love embraces the whole person. It violates communion with a person to not seem them holistically.
These two main approaches of science contrast with the one “Church approved” approach of science, that of Natural Family Planning (NFP). In this approach, knowledge of a woman’s fertility is used to time sex so that pregnancy is achieved or put off. This is not your grandma’s rhythm method, but modern science applied in real life to achieve results on par with the other mentioned scientific methods of postponing pregnancy.
At root, this method is derived from the fact that no one, not even married couples, are required to have sex. To force a spouse to have sex is rape, and there is no place for that in civilized society. So a couple may always choose to refrain from sex when a woman is fertile. This method uses the knowledge imparted by science to determine when a woman is fertile, and applies that knowledge to the decision making process about sex. Sex, when it takes place, embraces the other person in their entirety without a barrier and without destruction of healthy body tissue.
Externally the effectiveness is similar, and if that was all that was looked at NFP would just be another method of contraception. However, in regards to contraception it is not postponing or avoiding pregnancy that the Church has a problem with, but rather how the method effects communion between two lovers. What the Church teaches is wrong are those methods which break down communion and fellowship, not those methods which stop pregnancy from occurring. To reject a healthy wife in favor of disabling her fertility, or creating separation between people in their most intimate moments of love, these are what the Church disapproves of because these are actions of people not maximally open to communion and love. Natural Family Planning is the only scientifically devised method of birth control that retains respect for the communion of husband and wife, and that is why the Church is in favor of it while opposed to other methods. Catholicism practiced at its best is laser focused upon increasing love and communion between people, and so love is the standard by which scientific techniques are judged good or bad to practice.