The motivation behind the Catholic Church's opposition to birth control can be debated, but it would be most useful to know what the Church itself has actually stated. In this writeup I summarize the reasons for the opposition given in Pope Paul VI's Humanae Vitae (all quotes are from the English translation archived at www.vatican.va):

Problem and Competency of the Magisterium

  • "The transmission of human life is a most serious role in which married people collaborate freely and responsibly with God the Creator." In other words, marriage and procreation are not just private matters; they have moral aspects on which the Church has an authority to speak.
  • In our time there have been changes in our ability to regulate aspects of human life (science and technology) and in the world at large which provides reasons to do so (overpopulation, the growing understanding of the dignity of women). These have brought about questions as to the appropriateness of using artifical birth control.
  • These questions can be answered with a "moral teaching on marriage -- a teaching which is based on the natural law as illuminated and enriched by divine Revelation." Given by Jesus, the Church has the authority to interpret such moral teaching as based not only on the "law of the Gospel but also of the natural law. For the natural law, too, declares the will of God."

Doctrinal Principles

  • God's Loving Design: Marriage is "the wise and provident institution of God the Creator, whose purpose was to effect in man His loving design." As such it is intimately tied to the Church, and "the marriage of those who have been baptized is, in addition, invested with the dignity of a sacramental sign of grace, for it represents the union of Christ and His Church."
  • Married Love: Married love is: "fully human, a compound of sense and spirit," "an act of free will," "a love which is total," "faithful and exclusive," "and fecund." Married love goes beyong the two humans who enter into it; "children are really the supreme gift of marriage and contribute in the highest degree to their parents' welfare."
  • Responsible Parenthood: Married persons "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." They have a responsibility not only to future generations and potential future generations, but to God who has created the institution of marriage.
  • Observing the Natural Law: The married conjugal act is "noble and worthy," even if foreseen to be infertile for reasons independent of the will of the married persons. "The Church, nevertheless, in urging men to the observance of the precepts of the natural law, which it interprets by its constant doctrine, teaches that each and every marital act must of necessity retain its intrinsic relationship to the procreation of human life."
  • Union and Procreation: Because of the way God authored man and woman (biologically), "the fundamental nature of the marriage act, while uniting husband and wife in the closest intimacy, also renders them capable of generating new life." Therefore there is an inseparable connection between the unitive and procreative significances of marriage, which man of his own initiative may not break.
  • Faithfulness to God's Design: "an act of mutual love which impairs the capacity to transmit life which God the Creator, through specific laws, has built into it, frustrates His design which constitutes the norm of marriage, and contradicts the will of the Author of life." Our human sexual functions, just like our body and our life, are not ours to control; we must always look to the will of God.
  • Unlawful Birth Control Methods: From the nature of married love, and the natural law given by God, the Church can determine that: acts interrupting the generative process already begun, acts of abortion or sterilization (permanent or temporary), and acts that as a means or end prevent procreation before, during, or after sexual intercourse, are wrong. And: "though it is true that sometimes it is lawful to tolerate a lesser moral evil in order to avoid a greater evil or in order to promote a greater good, it is never lawful, even for the gravest reasons, to do evil that good may come of it."
  • Lawful Therapeutic Means: "the Church does not consider at all illicit the use of those therapeutic means necessary to cure bodily diseases, even if a foreseeable impediment to procreation should result therefrom — provided such impediment is not directly intended for any motive whatsoever."
  • Recourse to Infertile Periods: "The Church is the first to praise and commend the application of human intelligence to an activity in which a rational creature such as man is so closely associated with his Creator. But she affirms that this must be done within the limits of the order of reality established by God." To use contraception is to interrupt a natural process and offend the dignity of marriage as created by God, but to take advantage of infertile periods is to "rightly use a faculty provided them by nature."
  • Consequences of Artifical Methods: Birth control can lead to or encourage "marital infidelity and a general lowering of moral standards." Also, "a man who grows accustomed to the use of contraceptive methods may forget the reverence due to a woman, and, disregarding her physical and emotional equilibrium, reduce her to being a mere instrument for the satisfaction of his own desires, no longer considering her as his partner whom he should surround with care and affection." "Finally, careful consideration should be given to the danger of this power passing into the hands of those public authorities who care little for the precepts of the moral law." It would truly be dangerous for governments or other power structures to infringe on the dignity of marriage and the free will of persons by encouraging or even forcing the use of birth control to further ends not in harmony with the will of God.
  • Limit's to Man's Power: "unless we are willing that the responsibility of procreating life should be left to the arbitrary decision of men, we must accept that there are certain limits, beyond which it is wrong to go, to the power of man over his own body and its natural functions — limits, let it be said, which no one, whether as a private individual or as a public authority, can lawfully exceed."
  • Concern of the Church: "It is to be anticipated that perhaps not everyone will easily accept this particular teaching," but the Church "does not, because of this, evade the duty imposed on her of proclaiming humbly but firmly the entire moral law, both natural and evangelical. . . . Since the Church did not make either of these laws, she cannot be their arbiter — only their guardian and interpreter."

First Note: If the Church really opposes birth control to maximize membership, why doesn't she allow all of her priests, monks, and nuns to marry and procreate? Why are abstinence from sex until marriage and lifelong celibacy valued so much?

Second Note: izubachi states that the Church considers the use of contraception a sin because Paul VI had a temper tantrum when a commission he appointed didn't agree with him, but the commission could only disagree with his position if he already held it . . . so why did Paul VI and Catholic tradition oppose contraception in the first place? THAT is what is explained in Humanae Vitae. Also, a council of "esteemed members" is with authority only so much as the Church lends it authority. . . however the Popes, Ecumenical Councils of the Bishops of the World Ratified by the Popes, the theology of Sacred Scripture, and the writings of the Sainty Doctors of the Church, all derive their authority more directly from God. izubachi may not like it, and most Catholics might not like it, but they should realize that all of these authoritative sources are overwhelmingly in agreement that artifical contraception is sinful . . . for the Vicar of Christ on Earth to attempt to change Catholic Doctrine because of the recommendtions of a council of primarily laymen who disagree would be irresponsible, and indeed unCatholic.