Too-facile dismissals of Natural Law are, in my experience, rooted in criticisms of too-facile expressions of the Natural Law. Aristotle's view of slaves and women comes to mind, but there are many others. More recently, a host of issues mentioned in the document have been the subject of criticism by those opposed to a natural law approach:

[M]ajor complaints result from the extensive practice of divorce, cohabitation, contraception, procedures of artificial procreation and same-sex unions. Other complaints against the natural law come from the poorest areas and those least influenced by western thought—especially some African states—which cite the phenomena of machismo, polygamy, marriages between teens and preteens, and divorce in cases of sterility or a lack of a male heir, as well as incest and other aberrant practices. (27)

It is true that some of these issues have in the past been addressed with facile appeals to the Natural Law—for example, by proof-texting the Genesis account of creation. Yet it is still necessary to ask basic questions about the reality of human beings in the world, and ask what ultimately serves justice and manifests divine love.

What is significant about the document—and what it portends for the synod—is that its focus is not doctrinal, but pastoral. (In this, it is very much an heir to Gaudium et Spes, the Pastoral Constitution on the Church in the Modern World of the Second Vatican Council, which it often quotes directly and indirectly.) It is clear to me that no major doctrinal changes are at all in the works; but it is equally clear to me that the synod will call for significant changes to established pastoral practices.

Again, the accent is on mercy. The overriding question for the synod is not "how can we get Catholics to believe what we've been saying all these years?" It is rather "how can the Church speak a word of God's mercy to people?" It seeks to speak mercy to husbands and wives and children; but it also seeks to speak mercy to queer people; divorced people; couples indifferent toward children; women in abusive relationships; single parents; survivors of rape or incest. That mercy is a call to the entire Church to recover its most fundamental roots in fidelity to a loving God.

The mercy of God does not provide a temporary cover-up of personal misdeeds, but rather radically opens lives to reconciliation which brings new trust and serenity through true inward renewal. The pastoral care of families, far from limiting itself to a legal point of view, has a mission to recall the great vocation of love to which each person is called and to help a person live up to the dignity of that calling. (80)

Most central to this project of mercy, then, is the recovery of a deep, authentic, robust appreciation of the love of God, and God's invitation to participate in it. The related task is to explode facsimiles of love, particularly those desires that, in the language of Saint Augustine, are "curved in on oneself" (incurvatus in se):

[T]he adjective "natural" often is understood by people as meaning "spontaneous" or "what comes naturally." Today, people tend to place a high value on personal feelings and emotions, aspects which appear "genuine" and "fundamental" and, therefore, to be followed "simply according to one's nature." The underlying anthropological concepts, on the one hand, look to an autonomy in human freedom which is not necessarily tied to an objective order in the nature of things, and, on the other hand, every human being's aspiration to happiness, which is simply understood as the realization of personal desires. (22)

In lay terms, this task is not about asserting a narrow view of natural law, but rather calling people to appreciate that there is a natural law—that the reality of their very lives is not a matter of what they themselves create out of nothing, but rather what they themselves receive as a gift from a prodigally loving God. The vocation to the sacrament of marriage, and the recognition that family life is a building block of the Church and society (pace Drew Christiansen's critique) is far from an exclusive club for the few; it is an eschatological sign for the whole world, in that it is the place where members become more like Christ in learning how to love.