In her recent First Things article, What Are Children For?, Paige Hochschild criticizes Dietrich von Hildebrand for thinking of procreation as a merely extrinsic purpose of marriage, as something which is in no way constitutive of its essence. She quotes him as saying that marriage is a "closed union" in which "each of the two parties is turned exclusively upon the other." As a result, she goes on, von Hildebrand can't possibly do justice to the political and communitarian dimensions of marriage. He "excludes from marriage's integral ordering, both in end and in meaning, the raising of children for the society of the city of God."
All of this seriously mis-represents von Hildebrand's real thought. It is true that he distinguishes between the primary end of marriage, which is procreation, and its primary meaning, which is conjugal love. But the point of this distinction is not to separate conjugal love from procreation, but rather to protect the former from being instrumentalized in relation to the latter. Marriage, von Hildebrand wants to stress, has a meaning and value of its own, even considered apart from its end of procreation.
One may quibble over the terminology von Hildebrand uses. Perhaps he should have explained better what he meant (technically) by calling conjugal love the "primary meaning" of marriage. But his main point is clear: he wants to move away from thinking of love as another "end" of marriage, which would have to be next and subordinate to procreation, which is, after all, the primary end. The truth is rather that conjugal love encompasses and informs all of marriage, including its three ends (procreation, mutual support and fidelity, remedy for concupiscence). Only if this is clearly maintained, can the integrity of marriage, and the dignity of spouses and children, be preserved. Karol Wojtyla (also criticized by Hochschild) makes a somewhat similar point in Love and Responsibility:
The personalistic norm [i.e. the norm which says that love is the only proper and adequate attitude towards a person] itself is not, of course, to be identified with any of the aims of marriage: a norm is never an end, nor is an end a norm. It is, however, a principle on which the proper realization of each of the aims mentioned, and of all of them together, depends—and by proper I mean in a manner befitting man as a person.
Likewise, Vatican II refers to conjugal love not as an end, but as the "form", or the "life-giving" and "unitive" principle of marriage.
To understand the way in which von Hildebrand links the end of procreation with conjugal love one has to look at his idea of "superabundant finality". (I am indebted on this point to an unpublished manuscript of Maria Fedoryka.) The basic idea is that children are not so much the direct aim and purpose of marriage and sexuality, but rather their natural fruit. Unlike a tool, in other words, which derives its entire meaning and value from its purpose, marriage and sexuality have a meaning and value in themselves, even considered apart from their natural ends. Marriage is an abundant good, a fruitful good, a good which naturally flows over into other goods. The mutual and total self-donation of the spouses to one another in marriage is and remains a high value, even if their union does not lead to children. Sexuality, likewise, is the bodily expression and actualization of conjugal love. In it, the spouses give themselves to each other. Their attention is, and ought to be, on one another. If this unitive dimension is missing, and the spouses not only hope for, but aim excusively at "having a baby", they may be said to use each other: for a noble end, to be sure, and perhaps willingly, but that does not change the utilitarian structure of their activity.
All this is important not only for the dignity of the spouses and for the integrity of their marriage, but also for their offspring. Children are begotten, not made (by the parents, that is). They are not the product of our activity, but the wonderful fruit of our (and God's) love. (That this is so, i.e. that love is the only origin worthy of a human person, is often overlooked in modern reproductive technologies.)
One might be tempted to think that at least from God's point of view, marriage is simply the means by which He has decided to increase the human race, and that He created love and sexual desire as an incentive to to make us cooperate willingly with His purposes. But that would be equally demeaning. God also, the God who is Love itself, has designed marriage as the loving and lasting union between a man and a woman, and sexuality as the enactment of that union. And he has also wonderfully ordained that same union as the most fitting way for children to come into this world.
Does this personalist view of marriage turn procreation into a merely external end of marriage? Is it an overly "romantic" or affective" as opposed to properly "metaphysical" view, as Hochschild seems to think? Not at all. Superabundant finality is as metaphysical a principle as instrumental finality. And the natural fruitfulness of a being or institution is as essential to it as any other faculty. Von Hildebrand, therefore, does not sever the link between the unitive and procreative meanings of marriage and sexuality. He rather sheds light on its true nature and reveals its deeply personal structure.
One more word about the quote mentioned above: In Marriage: The Mystery of Faithful Love, von Hildebrand does say that marriage is "a closed union … a relationship in which the regard of each one of the two parties is turned exclusively upon the other." But, as the context makes clear, he is speaking here about the exclusivity of spousal love that sets it apart from other loves, such as friendship or the love of neighbor. One can have many friends, but only one spouse. Von Hildebrand shows that this is not an arbitrary restriction placed on marital love (for the sake of the children, say, or for some other reason) but that it grows out of the nature of conjugal love itself. It is a kind of love that aims at a total and mutual self-donation, and is therefore possible only between two persons of the opposite sex. In other words, the exclusivity von Hildebrand refers to in the said quote has nothing to do with "the relative isolation of the modern family," as Hochschild seems to think, but rather describes the feature of conjugal love which, among other things, makes it incompatible with polygamy.