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Natural and Divine Law: Reclaiming the Tradition for Christian Ethics
by Jean Porter
Eerdmans, 399 pages, $28

Like the special threads the U.S. Mint implants by which genuine dollar bills are distinguished from counterfeit, there is a mark that distinguishes a genuine theory of natural law from false ones: the insistence that there are some moral truths rooted in human nature that we all really do know and that we simply cannot fail to know. Out of self-interest, or perhaps from loss of nerve, we may choose to deny these truths, but interiorly we still know them and we will eventually have to deal with the pangs of conscience that their violation generates.

Whatever else a given theorist of the natural law may emphasize, there can be no compromise on this central tenet. Unless there really is moral obligation, it will not be a form of natural law , and unless the immediate ground for that obligation is the metaphysical structure that makes a being human, the theory in question will not amount to natural law but an ethics of some other sort, whether divine command, Kantian deontology, utilitarianism, or something else. As Yves Simon and Heinrich Rommen long ago demonstrated, there is room for disagreement within the tradition of natural law about how one envisions the role played by God as the author of human nature, or about the tortuous problem of culpability when there is deeply rooted perversity of basic inclinations. But the objectivity of natural moral obligations is a nonnegotiable constant of the theory.

Only a sound currency, of course, is worth counterfeiting. Perhaps that is why there are so many efforts presently afoot to claim the natural law mantle. The “new natural law theory” associated with Germain Grisez and John Finnis is certainly the most redoubtable of the contenders now sparring with more traditional followers of Aquinas such as Ralph McInerny and Russell Hittinger. Some pretenders are easy to spot, as when Christian Traina’s Feminist Ethics and Natural Law tries to justify homosexual marriage on the warrant that “natural law’s concrete conclusions are dynamic and humanly generated to the same degree that humanity is.” Where nominalism rules, we may readily call the unnatural perfectly natural if we want to. But, by the test of the special thread, Jean Porter’s sophisticated historical argument in Natural and Divine Law resembles the clever machinations of modern counterfeiters. The placement of surrogate threads is subtle, but careful examination shows the authenticating marker to be missing.

Porter’s goal is to remind contemporary moral theologians of the structure and variety of medieval natural law theories, and in many ways she does an admirable job. Porter helpfully and correctly warns against the modernist assumption that natural law, properly understood, must be grounded in pure (that is, nonreligious) reason. Instead, she shows that medieval natural law theories always paid serious attention to the roles of Scripture and nature as well as reason. And not just any secular idea of human nature will do. She emphasizes ( la Redemptor Hominis ) that a proper understanding of the essence of human nature requires reference to the image of God in the person of Christ. This move raises the reader’s expectations about the theological reconstruction of natural law she wants to undertake. So when she successfully criticizes Hume’s idea of reason (that reason is merely an instrument in the service of passion and desire), the reader expects an argument about reason’s proper role in discerning man’s end, and thus the exceptionless moral norms that direct him to his fulfillment.

It has been a hallmark of genuine natural law theories that through rational reflection on human nature they arrive at the precise place where Scripture reports a firm commandment (against killing the innocent, for example, or violating marriage vows). Building on this convergence between reason and revelation, such thinkers as Aquinas developed an elaborate virtue ethics to outline what further perfections are possible and desirable for human nature, especially under the aid of grace. But natural law, like much of civil law, has the humbler task of collaring the criminal and resisting what may under no circumstances be condoned, a task that must be done before elaborating the possibilities for greater perfection. As Augustine noted in his commentary on the Gospel of John, freedom from sin by the keeping of the commandments is only the beginning of freedom. Yet Porter does not go there; instead she tries to use the tools of natural law to build what is fundamentally a revisionist theory of social and sexual ethics.

The book dwells at length on the variety of medieval theorists who invoked “natural law””philosophers and canon lawyers as well as moral theologians. Porter makes special use of twelfth-century thinkers who were fascinated with Aristotle’s philosophy of nature, and of the modern scholars such as Charles Homer Haskins and Richard Southern who studied them. Porter lays out a compelling case for considerable variation in how medieval thinkers envisioned natural law and its applications. But her treatment of medieval uses of Scripture is innocent of what scholars such as Henri de Lubac (especially in Medieval Exegesis ) and more recently Paul Quay have revealed about the pervasive insights for morality that the medievals’ thoroughgoing attentiveness to typology made possible. Mesmerized by current trends, Porter turns patronizing when the Scholastics seem to her to get something like the subordination of women within marriage wrong, noting that they “did not have the kind of historical/critical perspective on Scripture that would have enabled them to relativize these precepts.”

Porter is unpersuasive in her repeated claims that the figures under study tended to use the theological framework provided by Scripture, nature, and reason merely to legitimate the prevailing but often unquestioned views of their culture. In the area of sexuality, for instance (one of Porter’s two major concerns in this volume), she finds that natural law analysis was largely “a continuation of attitudes . . . of antipathy toward sexual pleasure . . . deeply ingrained in Western culture.”

The lack of the authenticating thread for genuine natural law-the nonnegotiable insistence that there are some universally valid precepts derivable by nature and unable not to be known (however much we are tempted to overlook them or pretend we do not know them)”is most clearly evident in the sections of each chapter where Porter sketches what contemporary moral theology can discover from her medieval labors. In the words of her own summary: “The Scholastic concept of the natural law, precisely because of its specifically theological character, does not yield the universally valid moral code that modern . . . natural law theorists have attempted to provide.” What it does offer, she tells us, is “something that is perhaps of even greater value . . . a framework for . . . a more realistic recognition of the irreducible diversity of human moral beliefs and practices, together with resources for a more nuanced assessment of these diverse mores.” The nuanced assessment she envisions would allow us to replace St. Paul’s complaint that certain types of acts are simply contrary to nature with a more open-minded vision that might appreciate the goodness inherent in all sexual pleasure and self-expression. Nuances such as these, however, are her attempt to direct our attention away from counterfeiting phrases such as “irreversible diversity.” Unity is the principle of intelligibility, and the lack of the special thread that marks all true natural law will alert any observant cashier that in this book false tender is being offered.

Joseph W. Koterski , S.J., is Professor of Philosophy at Fordham University and editor of the International Philosophical Quarterly.