The Church’s teaching about contraception, as was discussed in the previous post, is one of the most difficult to understand within today’s climate, and is subject to many misconceptions. Many people assume that the Church simply doesn’t care about married love, or that she is simply trying to force her members to have as many children as possible in order to keep the Church powerful. But this is not the case. The Church’s teaching is based on the natural law, which makes it clear that the purpose of the sexual act is procreation, and therefore the purpose of the sex drive is to procreate- which in turn means that it is perverted and unnatural to either mutilate our bodies or to destroy the integrity of the act in order to prevent procreation. This is the conclusion that right reason is meant to lead us to.
With this in mind, it becomes much easier to understand another aspect of Church teaching that is easily misunderstood- why periodic continence or Natural Family Planning (NFP) is regarded as an acceptable method of regulating births or avoiding pregnancy. The difference lies in respecting fertility as a healthy condition and maintaining the integrity of the marital act. Contraception is wrong not merely because it results in children not being conceived, but because of the way it does so- it deliberately thwarts the purpose of the sexual act. It either intentionally mutilates the human body such that its normal healthy functioning is impeded, or else reduces the sexual act to a mere pleasure-inducing imitation by means of a barrier. These go against the design of nature and are beneath the dignity of man.
Periodic continence, on the other hand, does not consist of mutilating the body’s healthy functioning or altering the form of the sexual act. Rather, it consists of recognizing, respecting, and working with the body’s normal fertility cycles and patterns. As everyone knows, the female body, according to nature’s design, goes through a fairly complicated monthly cycle. This cyclical pattern is very normal and natural, since every phase of that cycle is necessary to enable a child to be conceived and then nurtured in the womb. However, there is only a single very brief spot within this cycle in which conception can actually occur, surrounded by a window of only a few days during which an act of intercourse might result in conception. Periodic continence entails recognizing that window and abstaining from intercourse during that time.
“Sexual activity… does not cease to be legitimate even when, for reasons independent of their will, it is foreseen to be infertile. For its natural adaptation to the expression and strengthening of the union of husband and wife is not thereby suppressed. The fact is, as experience shows, that new life is not the result of each and every act of sexual intercourse,” Paul VI wrote in Humanae Vitae paragraph 11. “God has wisely ordered laws of nature and the incidence of fertility in such a way that successive births are already naturally spaced through the inherent operation of these laws.” In other words, it is not unnatural, and not wrong, to have sexual intercourse outside of the relatively few times when conception is possible, because it is still in its essence the same act, and the couple themselves have not taken any action to render infertile the act or their bodies.
This is also why women and men who are infertile for whatever other reason (including age or a medical condition) are still permitted to marry in the Church and have marital relations. After all, having children is never guaranteed! Married couples are called to be open to life by completing the act whereby children are conceived, not mutilating their bodies in the process, and any person/couple who is able to do this is free to marry, even if there are circumstances that mean no child will result barring a miracle. They are still doing everything nature intended.
The only physical/medical circumstance in which marriage cannot be contracted is impotence- a true physical inability to perform the marital act. The act is so central to the nature of marriage that, if it cannot be performed, marriage cannot be contracted. This is also probably the best argument for understanding why homosexual couples cannot get married. Persons of the same sex cannot perform the marital act! They can attempt to imitate it (a rather disgusting thought), but the proper form of the procreative sexual act is, by its very nature, only possible between one man and woman. Hence, same-sex attraction is inherently disordered in nature, somewhat similarly to how contraception is inherently disordered.
So this, in essence, is the difference between contraception and NFP, as well as the simple reason that homosexual marriage is considered unnatural and wrong. Other common questions and misgivings about NFP will be addressed in the next post, which will be the final installment in the series about marriage for the time being.