Modern Sources

The papal literature on NFP begins in earnest with Pius XII.⁸² However, a brief note must be made on Pius XI’s Casti Connubii, as the text has sometimes been interpreted as a condemnation of NFP. The text comes from paragraph 59: ⁸² Oddly, Leo XIII’s Arcanum is minimally relevant for our considerations here.

Holy Church knows well that not infrequently one of the parties is sinned against rather than sinning, when for a grave cause he or she reluctantly allows the perversion of the right order. In such a case, there is no sin, provided that, mindful of the law of charity, he or she does not neglect to seek to dissuade and to deter the partner from sin. Nor are those considered as acting against nature who in the married state use their right in the proper manner although on account of natural reasons either of time or of certain defects, new life cannot be brought forth. For in matrimony as well as in the use of the matrimonial rights there are also secondary ends, such as mutual aid, the cultivating of mutual love, and the quieting of concupiscence which husband and wife are not forbidden to consider so long as they are subordinated to the primary end and so long as the intrinsic nature of the act is preserved.^{83 83} Pius XI, Casti Connubii, §59 (Vatican City: Libreria Editrice Vaticana, 1930). What is more, Pius XI was a notoriously precise man, frequently interrupting himself during allocutions to go back and correct a remark to make it more accurate – certainly, had he meant to condemn the use of periodic continence for the spacing of births, he would have simply said so.

Paragraph 59 itself comes after a brief discussion of unnatural vice, which Pius XI describes several times in the preceding paragraphs (§53-§58) as frustrating the conjugal act. Onanism is specifically mentioned (§55).^{84 84} Onanism, or “withdrawal,” is better characterized as a special kind of self-abuse rather than contraception, as the act is, ultimately, not upon the woman but “upon oneself” so to speak. This violates the “intrinsic nature of the act,” in the language of Casti Connubii.

This paragraph first discusses a special case of the matter considered in the foregoing paragraphs. What if one spouse is inclined to practice unnatural vice by using the other? Either party could practice onanism (albeit this is more difficult for the woman) or self-mutilation, or the woman could either prevent sperm from entering the uterus by a spermicide, or she could remove the sperm from the birth canal after the act, or could in some other way make herself infertile, such as by an IUD or by inducing functional hypothalamic amenorrhea. (Of course, she could also take hormonal contraceptive pills, though this method was not available at the time the encyclical was published.) The Pope allows for the unwilling spouse to use the marriage act even given these circumstances or foreseen acts, so long as he or she is not consenting thereto and attempts to dissuade his or her spouse. (This does not include the use of barriers, which are a special case, as they change the object acted upon because there is not an integral one-flesh union of man and woman, rather there is an act upon a third item.)^{85 85} See Joseph M. Arias and Fr. Basil Cole O.P.’s article, “The Vademecum and Cooperation in Condomistic Intercourse,” National Catholic Bioethics Quarterly, vol. 11, Issue 2, Summer 2011, p. 301-328. In my view, spermicides should not be counted as a barrier properly speaking, as they are better described as being “with” the act rather than as the thing which is acted upon. However, if they were a barrier, there would be implications for the need for active resistance, as Arias and Cole discuss; but the case seems unclear enough that this could not be insisted upon as a grave precept.

Pius XI also deliberately excludes the opinion that infertility due to “time” or “certain defects” in themselves constitute grounds for judging a conjugal act as unnatural. This is in line with the doctrine of St. Thomas, as we have seen already, but this does not address clearly whether the choice to pursue relations only during such periods and on account of the infertility which they contain is sinful. It is the last two qualifications, and in particular their distinction, which is sometimes misunderstood as condemning NFP – “so long as they are subordinated to the primary end,” meaning subordinate to the procreative end, and “so long as the intrinsic nature of the act is preserved,” namely, there is not contraception of some kind, broadly considered. Why the distinction? Presumably, as Fr. Harrison notes, if Pius XI had wanted to condemn NFP he could have and would have used much clearer language.⁸⁶ Furthermore, the context of the Sacred Penitentiary decisions (especially the one issued very shortly after Casti Connubii) makes the anti-NFP interpretation extremely unlikely. How then do we explain this distinction between the act’s “intrinsic nature” and its “subordination to the primary end”? ⁸⁶ See Brian Harrison, “Is Natural Family Planning a Heresy?”: “For the sake of clarity, he almost certainly would have used the terminology of the theologians of that time: sinful onanismus on the one hand and on the other hand continencia periodica or usus exclusivus temporum agenneseos to refer to what we now call NFP. He would have stated unambiguously that the latter as well as the former was now to be judged sinful and unacceptable.”

It turns out the English translation of the encyclical is misleading. We read a much clearer doctrine in the editio typica, the text as it is found in the official records of the Holy See (the Acta Sanctae Sedis):

Optime etiam novit Sancta Ecclesia, non raro alterum ex coniugibus pati potius quam patrare peccatum, cum ob gravem omnino causam perversionem recti ordinis permittit, quam ipse non vult, eumque ideo sine culpa esse, modo etiam tunc caritatis legem meminerit et alterum a peccando arcere et removere ne negligat. Neque contra naturae ordinem agere ii dicendi sunt coniuges, qui iure suo recta et naturali ratione utuntur, etsi ob naturales sive temporis sive quorundam defectuum causas nova inde vita oriri non possit. Habentur enim tam in ipso matrimonio quam in coniugalis iuris usu etiam secundarii fines, ut sunt mutuum adiutorium mutuusque fovendus amor et concupiscentiae sedatio, quos intendere coniuges minime vetantur, dummodo salva semper sit intrinseca illius actus natura ideoque eius ad primarium finem debita ordinatio.^{87 87} AAS, vol. 22 (1930), p. 561. https://www.vatican.va/archive/aas/documents/AAS-22-1930-ocr.pdf. The phrase “quos intendere coniuges minime vetantur” is also not translated well – it might be better translated as, “which couples are not forbidden to intend.” The hypothesis I propose comes close to running afoul of this formulation but ultimately is in line with it, even if it is a somewhat strained reading – one may certainly intend such ends, as long as one of the two motives apart from procreation is also intended.

The word “ideoque” clarifies the relationship between the “intrinsica illius actus natura” and the “ordination” to the “primarium finem.” A better English translation of this section would read something like: “…as long as the intrinsic nature of the act is preserved and is therefore subject to the primary end.” The “therefore” – “ideoque” – connects the sexual act as integral in its externalities with its very subjection to the primary end, the bonum prolis. To have a sexual act whose intrinsic nature is preserved entails subordination to the primary end. They are not separate items, one regarding the physical character of the act, and the other regarding the interior disposition of the will. The latter necessarily flows from the former. This is also reflected in the Italian⁸⁸ and Spanish⁸⁹ editions of the text, though the French is as unclear as the English.^{90 88} “…fini che ai coniugi non è proibito di volere, purché sia sempre rispettata la natura intrinseca dell’atto e, per conseguenza, la sua subordinazione al fine principale.” https://www.vatican.va/content/pius-xi/it/encyclicals/documents/hf\_p-xi\_enc\_19301231\_casti-connubii.html ⁸⁹ “...cuya consecución en manera alguna está vedada a los esposos, siempre que quede a salvo la naturaleza intrínseca del acto y, por ende, su subordinación al fin primario.” https://www.vatican.va/content/pius-xi/es/encyclicals/documents/hf\_p-xi\_enc\_19301231\_casti-connubii.html ⁹⁰ There are some materials related to the drafting of Casti Connubii found in the Jesuit archives in Rome (ARSI), however, they appear to be minimally useful for understanding the history of the construction and translation of the document. In general, the translation of encyclicals at this time was not the healthiest operation. For example, see the reflections of Fr. Oswald Von Nell-Breuning, S.J., the ghostwriter of Quadragesimo Anno, which encyclical was published only a few months after Casti Connubii: https://crisismagazine.com/vault/documentation-the-drafting-of-quadragesimo-anno

Together with the context of paragraph 59, both in the encyclical and in the broader moment in which the encyclical was promulgated, the editio typica suffices to demonstrate definitively that Pius XI is not referring here to NFP but is rather referring to onanism and other unnatural acts which of their nature are not subordinated to the primary end because their structure does not admit of conception, unlike the natural or circumstantial infertility he discusses in the same paragraph.^{91 91} My own taxonomy differs slightly from Pius XI’s in Casti Connubii in that I distinguish between the intrinsic nature of the act as regards due matter (man as man completing the act with woman as woman) and as regards positive intervention upon secondary causes of conception and their means (contraception), but this is a refinement of semantics rather than a substantive disagreement.

While it is true Pius XI notes that the couple may pursue the secondary ends which he notes, like mutual aid, cultivating love, and relieving concupiscence, while evidently including having recourse to infertile periods to obtain these goods and avoid conception (which is the only natural reading of the text), he does not search out the proper motivation for pursuing those secondary ends in this way (conjugal activity) rather than another (i.e. prayer, fasting, works in the apostolate, etc.) in the context of such recourse. In short, he does not explain why one may engage in a particular sexual act knowing and willing that it will be sterile; rather, he only notes that there are other ends which can be pursued, and that using marriage during a known infertile time for these purposes is not immoral in itself.

Pius XII gives us two speeches to analyze, made within a month of each other. The first is the more famous of the two. It was delivered to Italian midwives:

It is necessary first of all to consider two hypotheses. If the application of that theory implies that husband and wife may use their matrimonial right even during the days of natural sterility no objection can be made. In this case they do not hinder or jeopardize in any way the consummation of the natural act and its ulterior natural consequences. It is exactly in this that the application of the theory, of which We are speaking, differs essentially from the abuse already mentioned, which consists in the perversion of the act itself. If, instead, husband and wife go further, that is, limiting the conjugal act exclusively to those periods, then their conduct must be examined more closely.^{92 92} Pope Pius XII, “Address to Participants in the Conference of the Italian Catholic Union of Obstetricians” (Vatican City: Libreria Editrice Vaticana, 1951)

Pius XII continues on to describe the necessity and quality of sufficient motives for recourse to periodic continence, which he takes quite seriously and which we will examine shortly. But here in this paragraph, he has clearly taught that NFP can be used without sin. The very next month, he gave a speech to a congress on the family, repeating his approval:

On the other hand, the Church knows how to consider with sympathy and understanding the real difficulties of married life in our day. Therefore in Our last discourse on conjugal morality We have affirmed the legitimacy and at the same time the limits – actually very large – of the regulation of births, which, contrary to so-called “birth control,” is compatible with God’s law. Indeed, one can hope (but in this matter the Church naturally leaves the judgment to medical science) that there might be able to be given that lawful method a sufficient basis, and the most recent information seems to confirm such a hope.^{93 93} Pope Pius XII, “Speech to ‘Fronte della Famiglia,’” AAS, vol. 43, 859 (Vatican City: Libreria Editrice Vaticana, 1951) The translation is my own. See also Pius XII, “Allocution to the 7th International Congress of Hematology, AAS vol. 50, 732-740 (1958), where he explicitly discusses the Ogino-Knaus method of NFP and clarifies Pius XI’s openness to NFP. Other material is present in the Apostolic Penitentiary archives which discusses Pius XII’s interventions over the Ogino-Knaus method with Brazilian bishops and a priest from Spain, the texts of which I hope to publish in due time.

Such was the doctrine of Pius XII on the issue.

Pope St. Paul VI brought the next major document to address the topic, in Humanae Vitae in 1968. While the encyclical is mainly concerned with explaining the illicit character of artificial contraception, the document also takes time to explain the difference between such methods and NFP, as well as to bring up, yet again, the need for sufficient motivation for using such a practice in the first place:

If therefore there are well-grounded reasons for spacing births, arising from the physical or psychological condition of husband or wife, or from external circumstances, the Church teaches that married people may then take advantage of the natural cycles immanent in the reproductive system and engage in marital intercourse only during those times that are infertile, thus controlling birth in a way which does not in the least offend the moral principles which We have just explained. Neither the Church nor her doctrine is inconsistent when she considers it lawful for married people to take advantage of the infertile period but condemns as always unlawful the use of means which directly prevent conception, even when the reasons given for the latter practice may appear to be upright and serious. In reality, these two cases are completely different. In the former the married couple rightly use a faculty provided them by nature. In the latter they obstruct the natural development of the generative process. It cannot be denied that in each case the married couple, for acceptable reasons, are both perfectly clear in their intention to avoid children and wish to make sure that none will result. But it is equally true that it is exclusively in the former case that husband and wife are ready to abstain from intercourse during the fertile period as often as for reasonable motives the birth of another child is not desirable. And when the infertile period recurs, they use their married intimacy to express their mutual love and safeguard their fidelity toward one another. In doing this they certainly give proof of a true and authentic love.^{94 94} Pope St. Paul VI, Humanae Vitae, §16 (Vatican City: Libreria Editrice Vaticana, 1968); note that in this paragraph the Pope also gives a passing treatment of the marital debt, though in vague language. An attempt to ground the popular notion that the expression of affection suffices of itself to excuse the marriage act is tenuous; it expects too much from this passing mention of “how couples behave” – which mention is also paired with the “safeguarding of fidelity.” Torquing these lines to try to make Paul VI a singular foundation at odds with the tradition is just to give this brief indicative allusion an unnatural amount of import.

The Pope clearly stresses the character of the natural defect of periodic infertility standing in opposition to the artificial defect introduced by contraception. One is taking advantage of a function of the well-functioning of the body itself, on the part of the woman, while the other is an intervention which destroys or inhibits the proper functioning of the faculty. He sees serious reasons (physical or psychological or external) as justification for avoiding conception by having recourse to periodic continence for conjugal acts, and relations during such infertile times as being useful for the expression of mutual love and, let it be noted, for the safeguarding of mutual fidelity.

A word of caution is warranted regarding the language of Humanae Vitae which has become so popular, namely, describing conjugal acts as needing to contain or respect the “unitive” and “procreative” aspects or dimensions. This way of speaking has proven itself over the decades to be rather unfortunate in that it has perhaps caused more confusion than clarity in the long run, not unlike the popular treatment of grave sin as requiring sufficient “knowledge” and “freedom.” While certainly a legitimate way to speak about the nature of properly ordered conjugal acts, the phraseology leaves much room for ambiguity about its precise meaning and thus its moral significance. It is certainly insufficient for the kind of exposition being undertaken in the present work, which is why it is not made use of.

The last major papal text on NFP comes from Pope St. John Paul II in Familiaris Consortio, notwithstanding any other references to periodic continence made by the Pontiff throughout his voluminous teachings on marriage and sexuality.

When, instead, by means of recourse to periods of infertility, the couple respect the inseparable connection between the unitive and procreative meanings of human sexuality, they are acting as “ministers” of God’s plan and they “benefit from” their sexuality according to the original dynamism of “total” self-giving, without manipulation or alteration. In the light of the experience of many couples and of the data provided by the different human sciences, theological reflection is able to perceive and is called to study further the difference, both anthropological and moral, between contraception and recourse to the rhythm of the cycle: it is a difference which is much wider and deeper than is usually thought, one which involves in the final analysis two irreconcilable concepts of the human person and of human sexuality. The choice of the natural rhythms involves accepting the cycle of the person, that is the woman, and thereby accepting dialogue, reciprocal respect, shared responsibility and self-control. To accept the cycle and to enter into dialogue means to recognize both the spiritual and corporal character of conjugal communion and to live personal love with its requirement of fidelity. In this context the couple comes to experience how conjugal communion is enriched with those values of tenderness and affection which constitute the inner soul of human sexuality, in its physical dimension also. In this way sexuality is respected and promoted in its truly and fully human dimension, and is never “used” as an “object” that, by breaking the personal unity of soul and body, strikes at God’s creation itself at the level of the deepest interaction of nature and person.^{95 95} Pope St. John Paul II, Familiaris Consortio, §32 (Vatican City: Libreria Editrice Vaticana, 1981).

Once again, we see NFP put in contradistinction with artificial birth control. St. John Paul II reflects further upon the subjective meaning of self-discipline and communication required to practice periodic continence.

Finally, the Catechism of the Catholic Church comments on the use of NFP in the following way:

For just reasons, spouses may wish to space the births of their children. It is their duty to make certain that their desire is not motivated by selfishness but is in conformity with the generosity appropriate to responsible parenthood. Moreover, they should conform their behavior to the objective criteria of morality . . . Periodic continence, that is, the methods of birth regulation based on self-observation and the use of infertile periods, is in conformity with the objective criteria of morality. These methods respect the bodies of the spouses, encourage tenderness between them, and favor the education of an authentic freedom. In contrast, “every action which, whether in anticipation of the conjugal act, or in its accomplishment, or in the development of its natural consequences, proposes, whether as an end or as a means, to render procreation impossible” is intrinsically evil.^{96 96} Catechism of the Catholic Church, (Vatican City: Libreria Editrice Vaticana, 2013) §2368, §2370 (Quotations therein come from Humanae Vitae, §14). Other significant texts include Gaudium et Spes, §51, and Pope St. John Paul II’s Letter to Families (1994).

This is a general summation of the tradition from the 1853 response from the Sacred Penitentiary to Familiaris Consortio. The Pastoral Constitution Gaudium et Spes of Vatican II had spoken similarly:

Let [married couples] thoughtfully take into account both their own welfare and that of their children, those already born and those which the future may bring. For this accounting they need to reckon with both the material and the spiritual conditions of the times as well as of their state in life. Finally, they should consult the interests of the family group, of temporal society, and of the Church herself. The parents themselves and no one else should ultimately make this judgment in the sight of God. But in their manner of acting, spouses should be aware that they cannot proceed arbitrarily, but must always be governed according to a conscience dutifully conformed to the divine law itself, and should be submissive toward the Church’s teaching office, which authentically interprets that law in the light of the Gospel. That divine law reveals and protects the integral meaning of conjugal love, and impels it toward a truly human fulfillment. Thus, trusting in divine Providence and refining the spirit of sacrifice, married Christians glorify the Creator and strive toward fulfillment in Christ when with a generous human and Christian sense of responsibility they acquit themselves of the duty to procreate. Among the couples who fulfil their God-given task in this way, those merit special mention who with a gallant heart and with wise and common deliberation, undertake to bring up suitably even a relatively large family.^{97 97} Gaudium et Spes, §50 (Vatican City: Libreria Editrice Vaticana, 1965).

The Council here briefly indicates the basic structure of authority, duty, and merit in regards to the procreation of children.

Minimal reflection on NFP as such exists in the teachings of Pope Benedict XVI⁹⁸ and Pope Francis.⁹⁹ Pope Leo XIV has not spoken publicly on the topic as of the date of the publication of this text. ⁹⁸ One treatment by Benedict XVI is found in a letter to an international congress on Humanae Vitae dated October 2, 2008. “It is true, moreover, that serious circumstances may develop in the couple’s growth which make it prudent to space out births or even to suspend them. And it is here that knowledge of the natural rhythms of the woman’s fertility becomes important for the couple’s life. The methods of observation which enable the couple to determine the periods of fertility permit them to administer what the Creator has wisely inscribed in human nature without interfering with the integral significance of sexual giving. In this way spouses, respecting the full truth of their love, will be able to modulate its expression in conformity with these rhythms without taking anything from the totality of the gift of self that union in the flesh expresses. Obviously, this requires maturity in love which is not instantly acquired but involves dialogue and reciprocal listening, as well as a special mastery of the sexual impulse in a journey of growth in virtue.” ⁹⁹ The post-synodal apostolic exhortation Amoris Laetitia in fact has surprisingly very little to say about NFP directly, limited only to a few passing comments in a single paragraph (222), quoting the Relatio Finalis and Humanae Vitae, 11. Pope Francis also offered his praise of the Billings Method in comments sent to a conference on NFP on April 28, 2023. https://press.vatican.va/content/salastampa/en/bollettino/pubblico/2023/04/28/230428b.html