The recent proliferation of arguments from human nature is one of the more surprising and promising episodes in the current culture wars. Natural law theorists have rightly insisted that the question of what human beings ought to do and the proper shape of social and legal institutions depends on the objective ends or goods of human nature. Moral law, that is, turns on what human beings are, and what they are for.

We should certainly welcome a return to the ethical and political insights of Aristotle, Cicero, and St. Thomas Aquinas: their subordination of the right to the good, the individual to the community, and autonomy to order provide powerful resources with which to combat the present libertine order. However, one cannot help but notice that the newfound fervor for natural law theory seems inspired more by the legal and rhetorical demand for a secular basis for traditional marriage norms than a desire for a thoroughgoing critique of individualism, consumerism, or secularism. While natural lawyers have a disproportionate influence in the resistance to same sex marriage, they remain relatively silent (or else ignored) on, say, usurious lending practices or unjust wages—for this reason, one might forgive those who suspect the newfound enthusiasm for natural law arguments to be motivated more by opportunism than conviction. (A proportionate insistence on economic and social justice would go a long way to proving this suspicion unfounded.)

And yet, a greater dependence on natural law arguments poses its own hazards. Natural law theorists may well view the marriage debates as an opening to introduce their wares to the broader public, offering an alternative way of resolving public disputes than the usual options of liberalism and utilitarianism. But it is one thing to resort to the natural law tradition for arguments devoid of explicitly Christian premises, and another entirely to present the natural law tradition as a form of secular reason. Unfortunately, proponents often advertise natural law on the grounds of its secularity. In the words of one natural law theorist, “Objectively true moral conclusions can be derived from premises that in no way presuppose any purported divine revelation, any body of scriptural writings, or any particular religious tradition.” In grounding ethical judgment in an account of human nature, however, natural law does not win its autonomy from Christian traditions.

There is, first, a gross historical anachronism in confusing the present dichotomy between the religious and secular (which originated in the sixteenth century from developments in Protestant theology) with the quite different distinction between faith and reason of a more ancient provenance. It is clearly erroneous to ascribe to Socrates, Plato, and Aristotle only a pure, “non-religious” form of reason—Socrates had his daemon, after all, Plato the spirit Eros to lift his soul to the divine, and Aristotle named his metaphysics (quite accurately) “theology.” Nor should we forget the oft expressed patristic sentiment: what was Plato but Moses speaking Greek? or Justin Martyr’s blunt assertion that Socrates and Heraclitus were Christians?1

The real trouble with packaging natural law as a form of secular reason lies in its conception of human nature as secular, immanent to the finite world, natural through and through. God’s revelation does not simply reveal new facts previously beyond the powers of the human intellect; it transforms our understanding of the world (as contingent), history (as belonging essentially rather than accidentally to finite things), and, perhaps most deeply, our understanding of the human as primordially ordered toward friendship with God. What revelation discloses is not some thing in addition to nature but rather the inner truth and paradoxically the elevation of nature. God’s self-revelation—or, if you prefer, the legacy of Christendom—irreversibly and fundamentally transformed the entire conceptual background within which we think.

Take the example of the virtues, those dispositions that orient a human being toward his final end. Love, the chief theological virtue, was not merely added to the pantheon of non-theological virtues like a new item to an inventory. Love reveals itself as the truth of the natural virtues, thereby transforming them. Love discloses the hidden depths of the cardinal virtues: temperance, fortitude, justice, and prudence.2 Augustine states in De moribus ecclesiae, “If virtue leads us to the happy life, I daresay virtue is nothing other than supreme love. For in describing virtue as fourfold, as I see it, we are talking about different movements of the one love.”3 These were known to the ancients, but only in part. Christ’s love discloses their plenitude. Likewise, the supernatural does not simply coat a natural core that remains unchanged; there is an innate affinity between the supernatural and the natural, reason and revelation, the contingencies of history and the transcendence of truth—however much the latter in each case exceeds the former.

The Christian transformation of moral philosophy goes deeper even than the cardinal virtues: “The concept of person,” Benedict XVI points out, “as well as the idea that stands behind this concept, is a product of Christian theology.”4 While in Aristotle’s considered judgment slaves were sub-human tools not worthy of regard, the Christian insistence that each person is made in the image of God and possesses an innate dignity, an inwardness that demands reverence, formed the foundation of both Christian and secular arguments against social ills ever since. From its lowly beginnings as a role or mask, the idea of the person (persona/prosopon) acquired from the Trinitarian and Christological debates new depth, revealing the dialogical character of the person, its irreducible relation to an other, and its superiority to objects. The person now signifies something worthy of dignity, love, and respect. It is difficult to state how deeply the idea of personhood as something unique, irreplaceable, and infinitely valuable has shaped our understanding of human nature, and what a profound loss we would suffer were it expunged from ethical discourse.

Now that Christ has transformed history, we cannot simply go back to a time before reason was transfigured by revelation. Thought in the West always begins within traditions shaped by the life, death, and resurrection of Christ and the spread of his Church, all of which fundamentally transformed our ideas about history, the world, and each other. To conceive of human nature aside from revelation requires, at this point in history, a Nietzschean overcoming of Christianity, an extirpation of God’s transformation of mankind, and perhaps even a (however strategic) negation of the hypostatic union. This is not simply a matter of considering humanity by the use of reason apart from revelation’s accretions to determine its natural end—neither reason nor human nature exist or operate in abstraction from history—human nature is not a static essence that happens to be instantiated in this or that historical epoch. One of the great ruptures in classical philosophical thought was the rejection of substantialism in favor of the idea of man as an essentially historical being. Christians insisted that human nature is constituted in and by specific historical narratives. As R. G. Collingwood puts it, “The process of historical change was no longer conceived as flowing, so to speak, over the surface of things and affecting their accidents only, but as involving their very substance and thus entailing a real creation and a real destruction.”5 We do not merely happen to be within time; our very being is temporal, swirling in the confluence of essence and existence, being and becoming. To articulate what man is, a trans-historical definition will not do; one must follow the lead of the Scriptures and tell his story.

To conceive of a natura pura (i.e., a human nature devoid of reference to the supernatural and transparent to reason) we would need to rid our traditions of thought of the vestiges of Christian revelation—and our model, at least in this respect, would be Nietzsche. Nietzsche recognized the degree to which Christianity had shaped the world, its refusal to stay within designated boundaries, the sheer saturation of God (at least the idea of God) into our thought, institutions, practices, laws, language, art, and so on. (Nietzsche even went so far as to declare, “We cannot get rid of God because we still believe in grammar.”) We cannot think of human nature after the Incarnation as others did before without engaging in the Nietzschean project of overcoming the idea of God. (Though we often, of course, adopt ideas from the Christian tradition unaware of their pedigree.) Whether one believes in the God of the scriptures or not, there is no question that the Judeo-Christian God has reshaped the order of things.

A “pure nature,” a limpid sphere of human existence enclosed within the confines of created finitude, is therefore not simply given. In neither theory nor practice is a secular humanity given at the start and a religious dimension later added. But a pure nature can perhaps be achieved by a labor of thought that clips the wings of the human spirit. Hear the call of Zarathustra: “Stay true to the earth, my brothers, with the power of your virtue! Let your gift-giving love and your knowledge serve the meaning of the earth! Do not let them fly away from earthly things and beat with their wings against eternal walls! Ah, there has always been so much virtue that has flown away! Lead, like me, the flown virtue back to the earth.”6

The danger of natural law, then, is this: however successful natural law might be as a rhetorical strategy the Christian idea of human nature cannot be reconciled with the secular location of human fulfillment in finite worldly ends: wealth, pleasure, autonomy, duty, even friendship or statecraft. There is no neutral concept of human nature to which both the secular and the religious can subscribe. If natural law is equally acceptable to believers and non-believers alike, this can only be because the concept of the human omits the premonitive longing for the transcendent—though it may be permitted an insipid intellectual curiosity for a first cause—and apart from a history in which man’s spiritual destiny is not just disclosed but accomplished.

The belief in a secular human nature onto which a super-nature is either imposed (if one is a believer) or not imposed (if one is a non-believer) is the product of Christian theology. As a purely descriptive historical matter, the secular did not coexist alongside religion; the secular emerged as a moment in a theological dialectic. The secular is itself one legacy of neo-scholastic anthropology.

The neo-scholastics constructed a “two story” model of human nature. They posited two distinct and externally related human ends: one natural and available to reason, and the other supernatural and found only in the “data of revelation.” Neo-scholastics such as Garrigou-Lagrange cleanly separated the natural and supernatural ends, positing reason as sufficient for the former and faith as necessary to the latter. Reason—so the argument goes—compels any person who understands the terms of the arguments to accept the principles of natural law. One problem with this approach should by now be clear: human reason is not an ethereal organ outside of time, culture, and history; our thought necessarily moves within historical and cultural formations that have already been deeply affected by Christian revelation. But there is a deeper anthropological error: the notion that man’s natural and supernatural ends can not only be sharply distinguished, but are extrinsically related.

This extrinsic relation between the natural and the supernatural characteristic of neo-scholastic thought shares a secret lineage with modern secularism. The idea of a purely natural end, a natura pura, devoid of an ontological drive for God, emerged at first as a hypothetical possibility. The natura pura was not thought to describe the existing human order: the question was whether God could have created rational beings that are purely natural—i.e., that are teleologically ordered toward finite ends.7  It was agreed that in fact human beings were not so created. Although God could have given human beings purely natural ends, the traditional claim was that God did not in fact do so.

Denys the Carthusian (1402-1471) elevated the natura pura from hypothesis to a historical claim: Adam was created with a finite, natural end, and the supernatural destiny of man was later superadded by God’s beneficence. Denys knew himself to be in open opposition to Aquinas. Cajetan (1469-1534) and Suarez (1548-1617), however, read the natura pura into Aquinas, injecting it into the commentatorial tradition.8 Both relied on Aristotle’s remark in On the Heavens that a being cannot be naturally ordered to an end which it has not the means to obtain by its own powers. Human beings do not possess the power to see God without divine help, and so there can be no natural desire to see God. If the Aristotelian principle of natural limits applies, there can be no intrinsic connection between man’s natural and supernatural destiny. Human beings can only be naturally ordered toward those worldly ends that lie within their power to grasp by their reason and attain by their efforts.

The two-story view cannot be attributed to Aquinas, who expressly considered this to apply only in the case of “irrational creatures,”9 emphasizing that between rational and irrational animal “there is no comparison.”10 Aquinas expressly considered and rejected the Aristotelian principle latched onto by Cajetan and Suarez in the case of human beings: “The rational creature in this surpasses all creation, because he has the capacity for the highest good through divine vision and enjoyment, although he needs the divine help of grace.”11

Aquinas instead championed the natural desire for the supernatural. For him, the ultimate end of human nature is the beatific vision. In De veritate, Aquinas declares: “The end on account of which [man] is a rational creature is to see God in his essence. . . . Man was made in order to see God: for God made the rational creature so that he might share his likeness, which consists in this vision.”12 Human nature is paradoxical, for “man was made in order to see God,” but he depends upon God’s grace to achieve his ultimate purpose. There is a charged tension in human beings, a constitutive incongruity, for human fulfillment is impossible without the freely given gift of grace.

As a matter of historical scholarship, there is no longer much controversy: Cajetan and Suarez erred in their exegesis of Aquinas.  The exegetical debate on which so much energy has been spent does not directly bear on whether the relation between the natural and supernatural is intrinsic or extrinsic. One position or the other is not any more likely to be true simply for Aquinas having held it. The interpretative history is interesting not so much for its exegetical foibles as its effect. Only from a theological point of view, a preexistent view of the supernatural, could an independent nature come into view—both chronologically (i.e., the concept of a secular or imminent nature did not precede the concept of the supernatural in time) or logically (i.e., the natural is always defined in contradistinction to the supernatural). Only by positing the supernatural in a particular way can the space be cleared for a secular, independent nature. The secular is not a universal constant, but one result of historical and theological processes.

Henri de Lubac’s detailed historical work traces the way in which neo-scholastic extrincism laid the foundation for the secular. Nicholas Healy aptly summarizes it: “According to de Lubac, the system of ‘pure nature’ prepared the soil for contemporary secularism insofar as it precluded the idea that the mystery of Jesus Christ reveals the original purposes and meaning of creation itself—reveals, we might say, the nature of nature.” If human destiny is divided into distinct and extrinsically related natural and supernatural ends, then it becomes rather easy to take the first without the second. De Lubac points out that the supernatural, once conceived as external to the natural, easily becomes superfluous.

“Grace,” one will say, “is neither a solution to the enigma of life, nor does it compete with man’s creative autonomy”; to want to introduce grace in some manner “into the intra-worldly dynamic of human evolution” would be to make it “an alienating element” and for that reason to provoke people to condemn it as “an intrusion that would eclipse the ethical grandeur of Prometheus.”

This alien offer may be simply declined. An extrinsic supernatural means that naturalism takes the form of jettisoning the superstitions of old, while keeping to the immutable laws of reason. Here we find a curious parallel: for both neo-scholastics and neo-atheists, one can be free of the Christian legacy by the simple intellectual denial of the God of the scriptures.

It is here that the natural law tradition holds so much promise: by showing the secular as a falsification of human nature, the desiccation of the human spirit, a rejection of the gift of life, a scrubbing out of the rapacious desire for God inscribed from the beginning on the human heart.

What should strike us about our human nature—what certainly struck Augustine and Aquinas—is its incompleteness, our inability to achieve our ultimate destiny by our own power, and our receptivity to the gift of grace. On this point it is Aquinas who proves the corrective to two-story neo-scholasticism. For human beatitude does not consist in two separate, entirely distinct ends, but is two-fold (in Aquinas’s words “duplex hominis beatitudo”): natural and supernatural. Our natural desire for the good, the true, and the beautiful cannot be fulfilled with worldly ends; but, on the other hand, neither does the promise of the end of the age render the created world evil or irrelevant. Aquinas strongly insisted on the insufficiency of natural happiness, its imperfection; true fulfillment may be found only in “the vision of the Divine Essence.”13 It is precisely this failure of man’s natural end to satisfy man’s desire that indicates and anticipates the supernatural. Aquinas’s natural desire for the supernatural forms the hinge that relates the two. The natural and supernatural ends are internally related, though the latter exceeds the former. It is this intrinsic relation between the two that wards off both the gnostic flights of the spirit and the ungrounded claim the secular places on the world.

Our ultimate purpose, therefore, must not be natural in the sense that it lies within our power to achieve by our own effort, but in the sense that human nature was made for friendship with God. Desire is more a universal human constant than our reason—for desire is self-consciously temporal, while rational enquiry more often than not mistakes the historically contingent for the absolute. (This is especially true of some of the more ahistorical strands of neo-scholasticism.) Charles Ryder, the protagonist in Evelyn Waugh’s Brideshead Revisited, captures this when he says to his mistress:

Perhaps all our loves are merely hints and symbols; vagabond-language scrawled on gateposts and paving stones along the weary road that others have tramped before us; perhaps you or I are types and this sadness which sometimes falls between us springs from disappointment in our search, each straining through and beyond the other, snatching a glimpse now and then of the shadow which turns the corner always a pace or two ahead of us.14

The surplus of desire over against all finite objects is more universal to the human condition than any system of thought. In our every dissatisfaction, the fleeting presence of the infinite God haunts us.

If in the human heart there has lurked from the beginning a desire for God, and history is the story of the superabundant fulfillment of that desire culminating in Jesus Christ, then human nature cannot be conceived “non-religiously”—that is, as directed only to imminent ends. Human nature has from time immemorial yearned for the supernatural; it has been shaped through salvation history and human nature itself has been united to the divine in the hypostatic union.

The fact that the wells of human reason have not yet been cleansed of the impurities of revelation, that our culturally inherited ideas and ways of thinking about what it means to be human have been so deeply affected by Jesus Christ, does not call for furthering the secular project, for chasing away the shadows of God from the face of nature with the sterile light of “pure” reason. To borrow a metaphor from Aquinas, we should not seek to turn wine back into water. We can in good conscience reject, with Benedict XVI, the idea that it is “possible to construct a rational philosophical picture of man intelligible to all and on which all men of goodwill can agree, the actual Christian doctrines being added to this as a sort of crowning conclusion.”15 The promise of natural law theory does not lie in its amenability to the secular world, but in its ability to deny the validity of the secular as such. In his seminal Theology and Social Theory, John Milbank pronounced: “Once there was no secular.” The classical tradition of natural law may end up teaching us that the secular rests is mistaken in its most fundamental ontological and anthropological assumptions. What we learn from the better Christian reflections on human nature may be that the secular story of man is a Christian heresy, and a shallow one at that.

  1. Augustine, De moribus ecclesiae 15.25. 

  2. Ibid. 

  3. Ibid. 

  4. Joseph Cardinal Ratzinger, “Concerning the notion of person in theology,” Communio 17.3 (Fall 1990): 439–54. 

  5. R. G. Collingwood, The Idea of History: With Lectures 1926–1928, ed. Jan van der Dussen, Revised (Oxford University Press, 1994), 47–48. 

  6. Friedrich Nietzsche, Thus Spoke Zarathustra, trans. Clancy Martin (Barnes and Noble Classics, 2005), 67. 

  7. Henri de Lubac, Augustinianism and Modern Theology, trans. Lancelot Sheppard (New York: Crossroad Publishing, 2000), 109. 

  8. Ibid., 158–59, 164–65. 

  9. St. Thomas Aquinas, ST II–I, q. 1, a. 2; cf. de Lubac, Augustianism, 172. 

  10. Ibid. 

  11. Aquinas, De malo, q. 1, c. 5; cf. de Lubac, Augustianism, 171. 

  12. Aquinas, De veritate, q. 8, a. 3, ob. 12 and q. 18, a. 1; cf. Henri de Lubac, Augustinianism, 171. 

  13. Henri de Lubac, “Duplex Hominis Beatitudo,” Communio 35.4 (Winter 2008): 603. 

  14. Evelyn Waugh, Brideshead Revisited (1993) 273–74. 

  15. Ratzinger, “The Dignity of the Human Person,” in Commentary on the Documents of Vatican II, vol. 5, ed. H. Vorgrimler (1969); quoted in Tracey Rowland, “Natural Law: From Neo-Thomism to Nuptial Mysticism,” Communio 35.4 (Fall 2008): 374–96, 378.