Two issues back, I spoke ill of a modern form of natural law theory that unsuccessfully attempts to translate an ancient tradition of moral reasoning into the incompatible language of secular reason. Because of an obscurity I allowed to slip into the fourth paragraph, several readers imagined that I was speaking in propria persona from that point on, rather than on behalf of a disenchanted modern rambling among the weed-thronged ruins; and some were dismayed. Edward Feser, for instance, issued a robust if confused denunciation, accusing me of numerous logical errors I did not commit and of being a Humean modernizer who doubts reason’s natural orientation toward the good. I suppose I should savor that as a refreshing change from the invective I usually attract; but, honestly, what most interested me about Feser’s argument were its fallacies, chief among them a notably simplistic understanding of such words as “revelation” and “supernatural.”

There is an old argument here, admittedly. Somewhere behind Feser’s argument slouches the specter of what is often called “two-tier Thomism”: a philosophical sect notable in part for the particularly impermeable partitions it erects between nature and grace, or nature and supernature, or natural reason and revelation, or philosophy and theology (and so on). To its adherents, it is the solution to the contradictions of modernity. To those of a more “integralist” bent (like me), it is a neo-scholastic deformation of Christian metaphysics that, far from offering an alternative to secular reason, is one of its chief theological accomplices. It also produces an approach to moral philosophy that must ultimately fail.

Before completing that thought, however, it might help to rehearse just a few of the conceptual obstacles our age erects in the path of natural law theory. So:

First. Finality’s fortuity . Most traditional accounts of natural law require a picture of nature as governed by final causality: For every substance, there are logically prior ends”proximate, remote, or transcendent”that guide its existence and unite it to the greater totality of a single cosmic, physical, moral, social continuum embraced within the providential finality of the divine. They assume, then, that from the “is” of a thing legitimate conclusions regarding its “ought” can be discerned, because nature herself”through her evident forms”instructs us in the elements of moral fulfillment. In our age, however, final causality is a concept confined within an ever more beleaguered and porous intellectual redoubt. One can easily enough demonstrate the reality of finality within nature, but modern scientific culture refuses to view it as in any sense a cause rather than the accidental consequence of an immanent material process. Within any organic system, for instance, ontogeny is fruitfully determined by strict formal constraints, but these are seen as the results of an incalculably vast series of fortuitous mutations and attritions, and therefore only the residue of an entirely stochastic phylogeny. Hence nature’s finality indicates no morally consequential ends (much less the supereminent finality of the Love that moves the stars), but is rather merely the emergent result of intrinsically meaningless brute events.

Second. Dame Nature, serial murderess . Even if final causality in nature is demonstrable, does it yield moral knowledge if there is no clear moral analogy between natural ends and the proper objects of human motive? After all, our modern narrative of nature is of an order shaped by immense ages of monstrous violence: mass extinctions, the cruel profligacy of an algorithmic logic that squanders ten thousand lives to fashion a single durable type, an evolutionary process that advances not despite, but because of, disease, warfare, predation, famine, and so on. And the majestic order thus forged? One of elemental caprice, natural calamity, the mercilessness of chance”injustice thrives, disaster befalls the innocent, and children suffer. Why, our deracinated modern might ask, should we believe that nature’s organizing finality, given the kinds of efficient causes it prompts into action, has moral implications that command imitation, obedience, or (most unlikely of all) love?

Third. Elective priorities. Assume, however, that we can establish the existence of a moral imperative implicit in the orderliness of the world, as perceived by a rational will that, for itself, must seek the good: Does that assure that we can prove what hierarchy of values follows from this, or how we should calculate the relative preponderance of diverse moral ends? Yes, we may all agree that murder is worse than rudeness; but beyond the most rudimentary level of ethical deliberation, pure logic proves insufficient as a guide to which ends truly command our primary obedience, and our arguments become ever more dependent upon prior evaluations and preferences that, as far as philosophy can discern, are culturally or psychologically contingent. Consistent natural law cases can be made for or against slavery, for example, or for or against capital punishment, depending on which values one has privileged at a level too elementary for philosophy to adjudicate. At some crucial point, natural law argument, pressed to disclose its principles, dissolves into sheer assertion.

Fourth. Theory’s limits. The most gallantly errant of Feser’s assertions is that, because reason necessarily seeks the good, there exists no gap into which any “Humean” separation of facts from values can insinuate itself. But obviously the gap lies in the dynamic interval between (in Maximus the Confessor’s terms) the “natural” and “gnomic” wills: between, that is, the innate yearning for the good that is the primal impulse of all rational life and the particular acts of judgment and choice by which finite individuals live. The venerable principle that the natural will is a pure ecstasy toward the good means that, at the level of our gnomic deliberations, whatever we will we inevitably desire as the good (for us); it does not mean that philosophical theory can by itself prove which facts imply which values, or that the good must naturally be understood as an incumbent “ought” rather than a compelling “I want.” Feser asserts that “purely philosophical arguments” can establish “objectively true moral conclusions.” And yet, curiously enough, they never, ever have. That is a bedtime story told to conjure away the night’s goblins, like the Leibnizian fable of the best possible world or the philosophe ’s fairy tale about the plain dictates of reason.

The question relentlessly left open in all of this is what “reason” really is. It is perfectly possible to believe that the whole natural dynamism of our reason and will is toward the good, and even to desire a true moral cultural renewal, and yet still to deny that natural law theory provides a sufficiently rich or logically coherent model of how the intellect can know moral truths. There is nothing scandalous in this unless one creates a false dilemma by imagining a real division between the discrete realms of supernatural and natural knowledge. Feser thinks of revelation as an extrinsic datum consisting in texts and dogmas, and of the supernatural as merely outside of nature, and believes there really is such a thing as purely natural reason. From that perspective, one cannot deny philosophy’s power to demonstrate objective moral truth without denying reason’s intrinsic capacity for the good. Like a Kantian (the two-tier Thomist’s alter ego), one must believe that philosophical theory’s limits are also reason’s.

These divisions are illusory. What we call “nature” is merely one mode of the disclosure of the “supernatural,” and natural reason merely one mode of revelation, and philosophy merely one (feeble) mode of reason’s ascent into the light of God. Nowhere, not even in the sciences, does there exist a “purely natural” realm of knowledge. To encounter the world is to encounter its being, which is gratuitously imparted to it from beyond the sphere of natural causes, known within the medium of an intentional consciousness, irreducible to immanent processes, that grasps finite reality only by being oriented toward a horizon of transcendental ends (or, better, “divine names”). There is a seamless continuity between the sight of a rose and the mystic’s vision of God; the latter is in fact implicit in the former, and saturates it, and but for this supernatural surfeit nothing natural could come into thought.

It does not then represent some grave failure of natural reason that philosophy cannot achieve definitive moral demonstrations, or that true knowledge of the good is impossible without calling upon other modes of knowledge: the (ubiquitous) supernatural illumination of a conscience”a heart”upon which the law is written, Platonic anamnesis (of the eternal forms or of what your mother taught you), cultural traditions with all their gracious moments of religious awakening (Jewish, pagan, Christian, Hindu, Taoist, Buddhist, Muslim, Sikh, and so on), prayer, inspiration, the cultivation of personal holiness, love of the arts, and so on. There is no single master discourse here, for the good can be known only in being seen , before and beyond all words. Certain fundamental moral truths, for instance, may necessarily remain unintelligible to someone incapable of appreciating Bach’s fifth Unaccompanied Cello Suite. For some it may seem an outrageous notion that, rather than a collection of purportedly incontrovertible proofs, the correct rhetoric of moral truth consists in a richer but more unmasterable appeal to the full range of human capacities and senses, physical and spiritual. I, however, see it as rather glorious: a confirmation that our whole being, in all its dimensions, is a single gracious vocation out of nonexistence to the station of created gods.