Recently on Catholic Answers Live, a caller asked me about whether there are morally licit means for a married couple to avoid pregnancy while still engaging in sexual intercourse. I explained that sterilization and contraception are a no-go, and that natural family planning (NFP)—a method that takes advantage of knowing the fertile and infertile periods of a woman’s menstrual cycle—is the only morally licit way to achieve such a goal.

But some, even within Catholic circles, might counter that using NFP to avoid pregnancy is nothing more than Catholiccontraception because the couple is not “open to life.” Not to intend conception (e.g., “we don’t want to conceive right now”) when engaging in the conjugal act, so it’s argued, renders natural family planning no more morally permissible than sterilization, coitus interruptus (the sin of Onan—see Gen. 38:9-10), or artificial contraception.

From my experience (I’m not the only one), this objection causes great concern for Catholic couples who discern that they’re legitimately ill equipped to have a child at a particular time. Therefore, I think it’s worth thinking through.

There are different approaches that we could take. I will focus on only one here: Show that the logical implications of the claim are unreasonable. If a claim’s logical implications are unreasonable, then the claim itself is unreasonable and thereby worthy of rejection.

So what are the implications?

Here’s one: It’s never morally licit for a married couple to have sex unless they want (intend) to conceive a child.

According to the claim, the married couple, in a given sexual act, are not “open to life.” In other words, their wills are not intending conception when they engage in the conjugal act.

But this schema applies to other scenarios as well—not just the case of a married couple using NFP to avoid pregnancy. Consider, for example, a married woman who is pregnant, a period during which nature makes conception impossible. Given the physical demands of gestating a child, it’s unlikely she would desire or want to conceive another child, or multiple children, while carrying her present child in the womb, even if, per impossibile, nature would allow for such a thing.

We can also imagine a married woman approaching the age where she can no longer naturally conceive, and her body is no longer in a condition to handle the physical burdens of carrying a child (perhaps sixty to seventy years of age). Given her physical frailty, it’s reasonable that she would no longer desire or want (intend) to conceive a child at her age.

Must we say the married women in the above examples have to avoid sexual intercourse with their husbands because they’re not wanting conception, or being “open to life”? The principle that we’re considering here demands a “yes.” They must abstain to remain morally upright, because the principle states that a married couple cannot enter the marital act unless they want (intend) to conceive a child.

I think most people would intuitively recognize that such an implication of the anti-NFP objection is unreasonable. But sometimes intuition isn’t enough. So let’s go a bit farther.

Suppose the above implication is true. This would seem to entail nature placing an unreasonable burden on married couples.

We mentioned above that nature sees to it in different ways that a woman is not fertile at times when she wouldn’t want to conceive a child. It could be because she’s pregnant, which involves a heavy physical burden, or it could be because of her age and physical frailty. These are all due to nature’s design.

Nature also sees to it that human beings have an intense drive to engage in the sexual act. Now, if it were sinful for a married couple to engage in the marital act when conception is not possible and the woman is not physically in a condition to desire conception, like in the above cases brought about by nature’s design, then nature would be placing an unreasonable burden on spouses—giving them the intense drive for sex but not allowing them to satisfy the drive for the majority of their married life.

There’s not a lot of time for sex within this moral schema when we consider that the woman would be pregnant for most of her childbearing years (and thus not able to conceive and not in a physical condition to desire conception) and naturally infertile after such a period (and thus not able to conceive and not in a physical condition to desire conception). Unless we want to say that nature places such a burden on married couples, which is unreasonable, we should reject the idea that NFP, at least in principle, is immoral.

I say “at least in principle” because it’s possible that a couple could avoid pregnancy via NFP for selfish reasons. But the locus of immorality wouldn’t be the use of NFP; it would be the selfishness of the couple.

There’s yet another implication in the anti-NFP objection: We can’t desire (intend) nature’s design for the lack of conception in a particular sexual act.

We mentioned above that nature sees to it in several different ways that a woman is not always fertile. It could be due to the specific time of her menstrual cycle. It could be because she’s pregnant, or it could be because of her age. These are all due to nature’s design. So nature sees to it that sexual intercourse during these periods will not achieve conception.

Now, if a married couple couldn’t morally engage in the marital act without desiring or wanting (intending) conception—i.e., being “open to life,” then we must say a couple cannot morally desire this order of nature.

But that seems unreasonable. If we can’t desire (intend) to follow this natural order, then which other natural order can’t we desire to follow? (Nature’s order for sex to be an expression of unitive love?)

Also, why would nature give couples a path to avoid conception in a particular sexual act and at the same time forbid them from walking down such a path? This view creates an irresolvable tension within nature, which in turn entails a lack of wisdom on the part of nature’s Creator.

Given that the logical implications of the objection considered here are unreasonable, we are thereby justified in concluding that the objection itself is unreasonable, and therefore worthy of rejection.

Although we can applaud Catholics who oppose NFP because they’re prioritizing being “open to life,” we can’t applaud their understanding of “open to life,” given that their moral logic entails unreasonable implications. They might have a Catholic will. But with this issue, there is a need to channel a Catholic intellect.

***This article was originally published by Catholic Answers Magazine Online on February 1, 2024.