I learned in these pages not long ago that it is perilous to express doubts regarding the persuasive power of most natural-law theory in today’s world. Not that I would dream of rehearsing the controversy again; but I will note that, at the time, I took my general point to be not that natural-law theory is inherently futile, but rather that its proponents often fail to grasp just how nihilistic the late modern view of reality has become, or how far our culture has gone toward losing any coherent sense of “nature” at all, let alone of any realm of moral meanings to which nature might afford access. In our time, any argument from immanent goods to transcendent ends must be prepared for by an attempt to “recover the world,” so to speak: a deeper, wider tuition of sensibility, imagination, and natural reverence.

Well, whether I was right or not, among the ­responses I provoked none surprised me more than the accusation of “fideism.” It had not occurred to me that anyone would imagine that the only alternative to a boundless confidence in reason’s competency to extract moral truths from nature’s evident forms, no matter what the prevailing cultural regime, is the belief that moral knowledge is the exclusive preserve of “revelation,” narrowly conceived as a body of inscrutable legislations irrupting into history from on high. If nothing else, excessive anxiety over the Scylla and Charybdis of “rationalism” and “fideism” seems like such a tarnished relic of the seventeenth century (or thereabouts). Both categories would have been unintelligible in the ancient or medieval worlds to which I had thought I was casting back a wistful eye—worlds in which reason and faith had not yet come to be regarded as utterly distinct, ultimately antithetical movements of the mind.

Precisely when the two concepts were set upon divergent paths, and precisely to whose charge the blame really should be laid—Scotists, nominalists, prophets of the novum organum, Cartesians, Encyclopaedists . . . —it is impossible to say. Whatever the case, though, at some point in the early modern period it became possible, and then normal, to think of “reason” as an essentially dispassionate and disinterested faculty capable of discerning first principles and deducing final conclusions without any surd of the irrational left over, and of “faith” as an essentially unreasoning paroxysm of the will, prompted by nameless yearnings and intuitions and hopes. Thereafter, one might still talk of “rational faith” or of “faithful reasoning,” but almost always with a sense of a paradox to be negotiated or ironically overcome.

Thus when late moderns come across, say, St. Anselm’s famous phrase “fides quaerens intellectum” (faith seeking understanding), they are often predisposed to see it at best as slightly duplicitous, at worst as expressing a somewhat contemptible ambition: the aspiration of an irrational passion (fervent, tender, fierce) to the dignity of a rational conviction (cold, adamantine, calm). But for Anselm it described something much more like the natural course that reason must always take, from its initial stirrings in an act of naive conjecture to its consummation in an act of reflective knowledge. All reasoning begins from a venture of trust whose truthfulness can be ascertained only at the end of the sequence of postulates and predicates and judgments to which it gives rise.

What, after all, warrants our belief in the power of rational consciousness to give us a true knowledge of ­reality? Whether we wish to acknowledge it or not, there is a fiduciary moment within every act of reason, which allows for thought’s first movement toward ends beyond itself. It is an implicit trust in an original accord between mind and world, mysterious but indissoluble; and it is one that (protest how we may) makes sense only if we presume some original ontological unity between consciousness and being. Every attempt of the rational mind to find the truth of things involves an implicit metaphysical presupposition: that there is some transcendent coincidence of world and soul, some original fullness of reality where they are always already one, which allows for their openness one to the other here below.

One traditional way of saying this is that mind and world, according to their different modes, both participate in the same eternal forms; but that merely defers the epistemological enigma to a higher level of reality. Even this accord between intelligence and intelligible forms seems necessarily to point toward some still-higher, more eminent unity in the simplicity of a first principle—in God. Only this permits us to believe that being is already manifestation, that it is by nature intelligible and comes to fruition as it discloses itself in soul: There is a reciprocal transparency of mind and world, an essential belonging of each to the other, because in their transcendent source they are one.

This is not, of course, the commonsense view of the matter today. Certainly, those who most like to flatter themselves that they are the austerest of rationalists (that is, atheists, materialists, metaphysical naturalists . . . that crowd) would find the notion that reason arises from an irreducibly fiduciary movement of the will risible, even perhaps sordid. But, notoriously, this creates something of a dilemma. For someone who takes, for instance, a rigorously Darwinian line, purged of all metaphysical postulates, there may exist a fortuitous correlation between mind and world, but certainly no essential harmony. Any congruence between thought and its objects is a kind of functional mechanical miracle, so to speak, achieved by incalculable ages of gradual adaptation and evolutionary attrition. So the world is not really known, it does not truly disclose itself as thought, because it has no ontological disposition to do so. And reason (whatever that may be) may work, but it cannot reveal. The division between mind and world admits of no mediation. All this being so, the unyielding rationalist turns out to be the most irrational fideist of all: one who believes in reason even though there cannot possibly be any reason for that belief.

It is tempting sometimes to read the whole history of modern continental philosophy as a cautionary fable regarding this divorce of reason from faith. Certainly, one sees the first clear signs of their estrangement from one another in Descartes’s vision of philosophy not primarily as the task of translating the splendor of being into luminous concepts, but rather as a rational reconstruction of reality erected upon the fundamentum inconcussum of subjective certitude: I cannot doubt that I think, and so my thinking is the indubitable principle upon which the trustworthiness of the world depends. In a sense, Descartes sought to find faith in reason, or to find a reason for faith; but in his project some enormous inversion of philosophical expectations had already occurred. The philosopher does not start from a faith in being’s intelligible disclosure of itself—in fact, he starts by explicitly abjuring such faith—but rather vests his trust in the power of the self to posit reality from its own unshakeable position. Thereafter it was only a short path to Kant’s “critically idealist” abandonment of the world “in itself” and retreat to the world available only to the human apparatus of perception. And an even shorter path led to “absolute” idealism’s pangs of metaphysical nostalgia and its attempt to reintegrate mind and world by forcing human reason to assume the burden of their ontological unity. The synthesis was, of course, inherently unstable. The grand, opulent, rococo edifice of Hegel’s system rested upon so shallow a foundation that it could not fail to collapse under the weight of its own magnificence. In proposing the “Idea” as the wellspring of both nature and history, working itself out by converting the inconclusiveness of time into the universality of Spirit, the Hegelian project invited the final triumph of sheer eventuality over rational order. At the denouement of the story, faith and reason are “reunited,” but only in the trivial sense that they dissolve into one common mist. This was the “liberating” discovery of postmodern philosophy (that delirious season of festive nihilism): Having forsaken its fiduciary ground, reason becomes pure positing, sheer assertion, jouissance. Without that original trust, that spiritual commitment, reason is not reason at all, but the purest irrationality, a game of the will. When faith and reason are truly separated from one another, neither can stand upon its own.

Like all cautionary tales, this one has a moral, but I am not sure I should presume to say precisely what it is. It has something to do with acknowledging that, in its very essence, all reasoning involves a venture of trust in an original orientation of truth to the mind and of the mind to truth, and in the ultimate unity of the two; and that, therefore, any attempt to argue from rational premises to rational conclusions that resolutely refuses to invoke what is and has always been revealed—in the mind’s most primordial encounter with reality—is not really a process of reasoning at all, but a journey toward absurdity. To put the matter in a vaguely Platonic fashion, we must enjoy a vision of the truth before we can reason our way to it: That is, we are always striving to remember something we in some sense already know, but do not yet understand.