Immanuel Kant Opus Postumum“Better late than never” is the motto of this review. The work known as Kant’s Opus Postumum occupied him during the last fifteen years of his working life, from 1786 to 1801. (He died at 80 in 1804.) The first English translation, which underlies this review, was published in 1993. The first German printing began in bowdlerized form in a Prussian provincial journal in 1882.

1882—that is the year after Michelson and Morley carried out their epoch-making experiment in search of the ether wind that must sweep over the earth, if it indeed travels through space filled with some sort of observable matter. It had a dramatic null result. The ether, however, had a huge role in Kant’s final project—final in both senses: last and eschatological. Whether Kant’s ether is in principle amenable to experiment or not is, to be sure, problematic; nonetheless there is, to my mind, a certain pathos to the posthumous work’s first publishing date, a pathos over and above the fact that it took nearly a century to appear.

Eckart Förster’s English edition of 1993 (which I should have studied ten years ago) is both an ordering and a selection. Kant left a manuscript, its pages covered in small tight writing with even tinier marginalia, of 527 sheets (1161 pages in the great Prussian Academy edition). The unnumbered leaves had, at one time, evidently been dropped on the floor—It was a labor to arrange and date them, a task mainly performed by Ernst Adickes in 1916, and then to make the work accessible by judicious selection, which is what Förster has done in the Cambridge edition. The latter effort was called for by the character of Kant’s writing—and, evidently, thinking—which is obsessively repetitive, ever circling about the issues in the terminological German of the Critiques glossed by formulaic Latin, only to explode suddenly into astounding new resolutions.

But then, this whole post-Critical legacy is astonishing. In 1790, Kant declared in his third Critique, the Critique of Judgment, that here “I conclude my entire Critical enterprise.” (170) Only the dependent metaphysical doctrine was to be worked out, that is, the system of a priori cognitions that are implied in the Critical foundations. But almost simultaneously finished business turned into unfinished business.

People who first saw the discombobulated manuscript put about the rumor of Kant’s senility. On the contrary: If in the three Critiques we see everything fall into its systematic “architectonic” place, in the Opus Postumum we see the foundations of the edifice broken open in the attempt to make the system more encompassing. Not that Kant is countermanding any major postulate of the Critical system, but rather that, in the effort to specify it, to make embodied nature and man fall out from it, he opens up its abysses, not only for the enthralled reader but, palpably, for himself—though the one chasm he steps over without the slightest regard is, to my mind at least, the most abysmal one; more of that below. In any case, during the last years, before he stopped writing, Kant seems to have returned not to a second childhood, but to a second vigor, to the searching modes of his pre-Critical years.

Here I want to insert a personal note. Why ever, I ask myself, did it take me so long to come to this remarkable work, especially when I was trying to think about Kantian topics: imagination, time, memory, and nonbeing? Well, I sought help in the Critiques and then elsewhere, in Aristotle, Plotinus, Augustine, Russell, Meinong, Husserl. Of the Opus Postumum only one—unforgettable—fragment had penetrated to me: “I, the Proprietor of the World.” It should have been intimation enough that the Critiques were, possibly, being transcended.

To me, Kant had never been primarily the systematician, whose thinking was a relentlessly unificatory construction and whose expression was an intricate terminological rococo. He was rather the philosopher who, more than the self-avowed tightrope dancer Nietzsche, built his edifice over an abyss. I found this the more absorbing since Kant seemed to me the soul of probity, a philosopher of originality and rectitude; the rarest of combinations in a vocation whose business ought to be not novelty but truth, though it has occasionally incited its professors to the self-exaltation of invention and the blue smoke of mystification. Kant is the man who reconceived philosophy as work (in the essay “On a Refined Tone Recently Raised in Philosophy,” 1796). Yet, in that sober mode he works himself late in life into strange new territories. Förster, to be sure, ends his book by saying that it is a futile exercise to speculate on the ultimate—unachieved—destination of this last phase. But to me, this speculation, though it may well be beyond the reach of scholarship, has a particular attraction: Do these late second sailings, to be found, for example, in Homer (Odyssey), Plato (Laws), Shakespeare (e.g., Cymbeline), Jane Austen (the unfinished Sanditon), as well as in the great musicians, express a necessary development implicit in the work of their floruits or novel, adventurous departures into terra incognita?

So as not to mystify the reader let me say here, for later amplification, what seems to me the drift of the Opus Postumum: It is a drift toward solipsism, the radical self-authorship or “autogenesis” of the human subject and the nature with which it surrounds itself.

Now to Kant’s work itself. My advice is to reverse good St. John’s practice and to read Förster’s explication of the Opus Postumum first. It is a conscientious and in places brilliant introduction to what is, after all, an unwieldy, unrevised and unfinished masterpiece.

Critique-of-pure-reason-by-immanuel-kant-188x300Since, however, the Opus Postumum takes off from the three Critiques, particularly from the first, the Critique of Pure Reason (A edition 1781, B edition 1786), I will give a very stripped-down and tailored version for those few alumni who don’t perfectly recall that high point of their junior year.(1) Then, since I can make the attraction of the Opus Postumum most plausible by listing the above-mentioned rifts and chasms in the first Critique, I will articulate the global perplexities that have always accompanied any local understanding I thought I had achieved.(2) Then, with Förster’s help, I shall give a brief sketch of the main topics of the Opus Postumum,(3) which I shall follow with a summary of the way in which Kant’s last work confirms or reshapes or resolves my perplexities.(4) Finally, I will attempt to say a word about the work’s bearing on Kant’s afterlife in our contemporary thinking.(5)

1. Though Kant did not expect, while working on the first Critique (which deals with theoretical reason as it constitutes nature), to write a second Critique on practical reason (that is, on moral action), it is arguable that his central concern is all along with morality, with human reason as it causes deeds. From that point of view, the mission of the first Critique is to ground a system of deterministic nature in deliberate juxtaposition to the spontaneity of the freedom evinced by the rational will when it acts as it ought, from the realm of nature is a system of necessary and universal rules, which we, ourselves, both constitute and cognize: We can know nature with certainty because we are its authors. (The terms pertaining to this cognition itself rather than to its objects are called “transcendental,” or almost synonymously, “Critical:” concerned with the conditions that make knowledge possible.) Though the first Critique, as it finally appeared, has as its positive consequence the grounding of experience, meaning the real knowledge of nature, its negative impact is to clear a region for human freedom conceived as autonomy, self-subjection to self-given law. Kant does this by showing that the theoretical understanding and the reason which organizes it are strictly limited to human experience and incapable of dealing with transcendent questions except in terms of “ideals” expressing the human need for completeness.

The crucial difficulty in establishing a sure and certain knowledge of nature is for Kant the doubt cast by Hume on causality: Cause is nowhere to be observed; we see constant conjunctions of events but never necessary interconnections among them. Kant’s answer, the crux of his solution, is that we know our way through nature with complete certainty because and insofar as we make it. Thus its laws are ours from “the very first”—a priori.

Our cognitive constitution is twofold: by our understanding, we think spontaneously (that is, originating out of ourselves) and also discursively (that is, by connecting concepts), thereby unifying manifolds; by our sensibility we are affected receptively by intuitions which are already given as unities. The understanding is thus a formal, logical faculty whose categories are adapted from a well-established tradition. But these categories are empty grasps in the absence of the pure material of the intuition to fill them, where “pure” means unaffected by ordinary sensory influence.

To me, this pure, pre-experiential sensibility and its pure, non-sensory matter is Kant’s most original, not to say mind-boggling, discovery (or invention—I am as perplexed about it now as ever), for a sensibility is, after all, usually understood to be a capacity for being affected by the senses. It has two branches. The pure “inner” intuition is our sense of time. It is pure because it is analytically prior to sensation. It is “inner” because it is, in ways that become progressively more unclear in the second edition of the Critique and in the Opus Postumum, closer to our ego, called the “transcendental apperception,” meaning the subject, the I that underlies every object we present to ourselves. For that is what human consciousness means for Kant: presenting objects to ourselves. Self-consciousness, or apperception, is awareness of the I that is putting this object before itself. It is that awareness which is said in the first Critique to represent itself to us as a phenomenon in inner sense; we know ourselves as pure egos when we attend to numerable time as it ticks away.

The corresponding outer sense is pure space. All we intuit (except ourselves—so far) we give the form of space; space is not formal (as is thinking), but formative. In this pre-sensory sensorium, we find externality within us. Or better, to assume the form of externality objects must be within our receptive sensibility, together with the sensations that give them their quality, the material manifold that gives them body. Nothing could be more contrary to our ordinary sense of things, where “outside” means precisely not within.

What is the purpose of this dizzying reversal, Kant’s sequel to the Copernican revolution? That first revolution made the sun stand still and our earth move, while this one makes us again home base, though now the world moves to our measure rather than to a divine maker’s plan. Kant’s purpose is to bring causality from an outside world, where it is objectively non-observable, into us where it is subjectively an inherent necessity of our cognitive constitution.

There is a missing step in this sketch, the notoriously fugitive “Schematism of the Pure Concept of the Understanding.” (B 176 ff.) It is the crux of the crux of the positive Critique, and its brevity should warn us that something is the matter. Schematizing is the work of the imagination; it is not the capacity for fantasy, but a “transcendental” faculty, one that makes knowledge possible. It is, in its depths, responsible for the mystery of conjoining the unconjoinable. It effects this by bringing forth a general diagram (Kant calls it a “monogram”) intended to draw together the absolutely disparate effects of the formally functioning understanding and the formatively receptive intuition. Thus time and space are to be conceptualized or, if you like, the concepts of the understanding are to be affected by time and space.

Kant hurriedly carries out this “dry and boring dissection” for the case of time. For example, the concept of cause, when time-imbued, becomes the necessary succession of one thing upon another according to a ruling concept. At this moment the possibility of a causal science that has certainty is grounded. (Here “possibility” does not refer to what might happen but to that which enables knowledge to become real.)

Kant silently and completely omits the schematizing of space. I had always supposed that, whatever difficulties I might have, Kant thought it was too easy. I couldn’t have been more wrong. Förster shows that it was too hard, and thereby hangs the tale of the Opus Postumum.(59)

2. First to me, among those deep perplexities that gives the Critiques their philosophical poignancy, have been the space puzzles already alluded to (the underprivileging of space in the Schematism) along with other, related ones.

In the second edition of the first Critique, Kant inserted a sort of time bomb, the famous section called the “Refutation of Idealism”(B 274, xxxix), in which he aimed to show that time itself can only be perceived as a determined phenomenon by us when observed against “something permanent in space,” that is, against matter: “The consciousness of my own existence is at the same time a consciousness of other things outside me.”(B 276) Where, I ask myself, has the first function of the “inner” sense gone? What is now particularly internal about my self-perception?

But so is the very meaning of space as “outer sense” a puzzle. Outerness seems to mean three things at once: It means extension, the way a spatial dimension consists of parts outside of each other, stretching away from themselves. It means, second, externality, the way objects are experienced as outside of the subject. And it means, thirdly, outside and “going beyond” us—the literal sense of “transcendent” (as distinct from “transcendental”), though this is a region in principle unreachable. For what we know, we know in us. That is, after all, what Kant intends to show in the negative part of the Critique, the “Transcendental Dialectic,” which exposes the illusions reason falls into in going beyond the limits of our experience”—and is thus the critique of pure reason proper.

There is, second, a puzzle that arises incidentally from the multivalence of Critical terms. The categories, Kant repeats emphatically, have no being on their own and achieve meaning only as they grasp intuitive material. Take then the category of unity which imposes oneness on manifolds of sense. There is, however, also the unity that reason strives for as an ideal, but can reach only illusorily. And there is “the synthetic unity of apperception,” the unifying work of the subject deep beneath appearance, its chief theoretical effect. Whence, we might ask, does Kant get the notion of unity to begin with? Is there not something suspect about this transcendental notion—and others, for example, “thing”—which are necessary to establish the transcendental terms of the Critiques but which are in traditional metaphysics terms of transcendence, the attributes of Being that are beyond sensory experience? How does Kant come to know these terms of Critical thought that are antecedent to properly certified knowledge?

A third enigma is immediately connected with the space puzzles. The dialectic of reason is intended to clear the decks for human freedom and for the exercise of practical reason, which expresses itself in deeds. But the system of nature grounded in the positive part of the Critique is deterministic. There are no loose joints. How then does moral action appear in the natural world? How does it actually change events determined by natural laws? How do we, as moral beings, insert ourselves into, intervene in, nature? Further, where, in fact, are we in the world as phenomenal, perceiving subjects? In the Critique of Pure Reason there is matter, but no bodies, human or natural—nor in the second Critique, that of Practical Reason. The simultaneous actuality of moral deed and natural events is a mystery: How does the practical reason make our muscles do the right thing?

The fourth open question is this: How far is nature specified by the Critical grounds and their ensuing principles? Are the types of forces necessarily operating in nature specifiable, and are their mathematical laws determinable a priori? How thoroughgoing are the grounds of possibility, or in Kant’s terms: “Can a complete metaphysical doctrine of nature be worked out such as will descend to and determine the actual laws of physics?” But then, what of observation, what of contingency? Is anything not under our own rules? Is the world nothing but our mirror?

Thence arises the fifth question, truly a mystery. Whence comes the matter of sensation which fills our space with its quantities and qualities and reflects to us our time by being the permanent material background against which motions appear? Is the occasion for the appearance of this matter infused into us transcendently, from beyond, or are we, its authors, not only formally, formatively, but really, substantively? I would say that this is the most unregarded, the totally unregarded, question in Kant’s writing—and in his thought as well: Are we, after all, buffeted by transcendent influxes? Or are we, when all has been worked out, shown to be our own authors in every respect—which would be brute solipsism, the philosophy of solus ipse “I alone, by myself?” But then what becomes of the ideal republic of mutually respectful moral beings and of the real political community of embodied human beings? What access do we then have to each other’s subjectivity?

Opus PostumumFinally, the sixth problem, not of doctrine but of argumentation: In the first Critique God is an ideal of reason, a required hypothesis or postulate if we are to act morally, an “as if ” representation whose existence is to us a necessary thought though its actuality is provably unprovable. As Kant works on the Opus Postumum the thought of a necessary God is increasingly sharpened and the claim more pointed, as shown in III: There are reasons that drive us to think that God is necessary; thus God’s existence must be first postulated and then acknowledged as real. He is actual for us: Est Deus in nobis, “There is a God—in us.”(dash and italics added, O.P. 209, 248) And: “Everything that thinks has a God.” That is to say, thinking requires a divinity and what thinking requires it must have—but only for the thinker. I simply cannot make out whether this God really exists or is after all what Kant himself would call a “subreption,” a surreptitious rustling of Being by a needy reason, or perhaps some third being I am too literal-minded to comprehend. To me it is marvelous how scintillatingly ambiguous the severely systematic Kant really is at great junctures.

Whether the above items are enigmas, questions, problems, puzzles, they each open up abysmal depth for the inquiry concerning human knowledge, action, and faith. Except for the spectacularly absent fifth question, concerning the origin of sensation and its stimulating matter, the Opus Postumum will show Kant grappling with these problems, sometimes only to focus them the more pressingly.

3. The early title of the Opus Postumum was “Transition from the Metaphysical Foundations of Natural Science to Physics.” The final title is “The Highest Standpoint of Transcendental Philosophy in the System of Ideas: God, the World, and Man in the World, Restricting Himself through Laws of Duty.”(Förster xliii) The distance between the titles betokens Kant’s winding himself from system-driven, downward doctrinal specification into ascending, comprehensive speculation. An obvious question will be whether these speculations in the main confirm or undermine the Critical enterprise. I want to say here that either way it is a thrilling business. If the gaping holes in the architecture of the system can be stopped and the foundations reinforced, the edifice will surely be the more magnificent and rivaled only by Hegel’s system. (I omit Aristotle, not so much because his philosophizing historically preceded the notion of philosophic system-making, but because he would in any case have thought that first philosophy should be problem driven, rather than system driven.) But if Kant is impelled to let his own system implode the outcome surely glows with the sober glory of thought outthinking. In the event, it seems to be a little of both.

The first question that has occupied students of the Opus Postumum concerns the project of the title. Why was a transition needed where was there a gap? The Metaphysical Foundations of Natural Science of 1786 seemed to provide a doctrinal transition from the general principles of the first Critique (which ground the laws of action and reaction, of causation in time and of the conservation of matter, “Analogies of Experience,” B 218 ff.) to the specific Newtonian Laws of Motion. That is to say, Kant has “constructed” these proto-laws, which means he has exhibited them in the intuition so as to display their necessary characteristics. Why, then, does this transition require another transition?

Förster gives a thoroughly satisfying answer.(59 ff.) As we saw, the spatial schematization of the categories is missing in the first Critique. The Metaphysical Foundation is in fact this missing schematism, the spatialization of the categories; I omit the details of Förster’s proof, but the argument is on the face of it convincing. At this point matter comes in: Kant must analyze empirical matter and its motion and then “construct” or “exhibit” the concept so obtained in space. (This is an epicycle in the so-called Critical circle: Kant analyzes the object, here matter, he intends to certify cognitively and then provides its transcendental conditions of possibility.)

Metaphysical Foundations of Natural ScienceBut in order for matter not just to occupy and traverse space, but to act dynamically (as it is empirically observed to do), to compact itself into bodies capable of moving each other, the forces of matter must be established. But forces are not to be observed as appearances (as Hume insisted) and are thus not constructible, that is, exhibit-able as configurations in the intuition. The Metaphysical Foundations do not succeed in solving the problem of cohesive bodies (as opposed to shapeless matter) held dynamically within their boundaries and exercising attractive as well as repulsive force on each other. Thus this metaphysical transition cannot present physics with its basic concepts. A gap bars the way to the categories’ objective validity, that is, to their empirical applicability; the attempted schematism is incomplete.

So a large part of the early work on the Opus Postumum is devoted to the Tantalus-labor of finding, a priori, the kinds and ratios of forces that will underwrite our natural world of dynamically moving cohesive bodies. Clearly Kant now intends (or always did) for the Critical grounding to reach very far into empirical, supposedly adventitious (unpredictable) cognition. We may wonder what will survive that passage between the Scylla of complete systematically and the Charybdis of empirical science.

Now come the ether proofs, a huge and weighty presence in the Opus Postumum. From a certain point on, Kant regards it as established that ether (or caloric), an “imponderable, incohesible, inexhaustible,” medium that is “universally distributed, all-penetrating, and all-moving”(O.P. 98, 92) is the condition of possibility of all the mechanical forces of matter whose effects (if not they themselves) are apparent in the making and the motions of bodies. Förster has lucidly reconstructed the intricate essential proof from its many sites and disparate approaches in the text.(89 ff.) It is worth attending to in spite of the negative Michelson-Morley ether experiment of 1881, not merely because it makes vivid the exigencies of the transcendental system (a system which someone—not myself—might indeed regard as having merely historical interest), but because it is the result of a deep meditation on the conditions of spatial experience.

To begin with, Förster points out that the Opus Postumum reverses the first Critique on the source of the unity of all appearances.(84) In that Critique, it was an ideal of reason to bring unity into our necessarily piecemeal perception. Then, in the third Critique, the Critique of Judgment (1719), a new source of unity comes on the scene: Nature herself is purposive and systematic. Under the influence of this reversal from reason ideally unifying nature to nature herself really unifying its forces into a system, a strange new situation arises. (The ultimate possibility of its arising I would trace back, without having worked it out sufficiently, to the above-mentioned ambivalence of the term “unity” in the first Critique: Is unity a subjective function or a transcendent characteristic of beings?) This situation is that nature herself must now contain a priori principles of its objective possibility; no longer are all a priori conditions of experience in the subject.

Or are they? Förster is inclined to think that the ether, as a condition of possibility of a system of nature (and hence of its science, physics) is an ideal of our reason, hence subjective.(91-92) But he does not deny that Kant himself wavered and sometimes speaks of the underlying medium as existing “outside the idea;”(O.P. 82) this oscillating effect is not unlike that of Kant’s treatment of God’s existence (see below).

The chief elements of the existence proof for the ether are as follows. From the subjective side: Empty space is not perceptible; a single space filled with moving forces is the condition of the possibility of unified experience which is knowledge of connected perceptions; hence, we must form the idea of an elementary material that is in space and time and has the characteristics listed above; thus, we get a subjective principle of the synthetic unity of possible experience such as must underlie physics.

From the objective side: Nature is the complex of all things that can be the objects of our senses and hence of experience, and we do have experience of outer objects. But experience requires that its objects form, for our judgments, a system which has a necessary unity according to one principle. The ether, distributed through space yet forming a collective whole, is the one and only candidate for such a system. Therefore, as making the whole of experience possible, it is actual.

Thus the ether is a unique—and very peculiar—external object that really exists in the—to my mind—oscillating way of Kant’s existence proofs, which argue from the enabling grounds of knowledge to the real existence of the object. As a ground of possibility it is not itself perceptible or observable. Thus, Kant might have replied to Michelson-Morley that, since the ether hypothesis was the condition of all experiments, it was itself not falsifiable by experiment. But they, as presumably positivist physicists, would have turned this reply around and said that what is not falsifiable is not positive knowledge. To me, too, the transcendental ether is, as I said, illuminating less as a real ground of science than as a reflection on the nature of our experience of space and its contents. For isn’t it the case, after all, that the material ether having been eradicated from physics, other fillers of space had to be found, such as fields of force and geometric conformations of space itself?

Immanuel Kant StatueIn any case, Kant considers that the specific dynamic properties he assigns to his ether solve the problem of systematizing the mechanical forces, attraction, repulsion, cohesion, whose effects are mathematicized in the Newtonian manner. The—surely superseded—details of this grounding are obscure to me and I can summon interest in the argument about them only insofar as they realize that “transition,” announced in the early title of the Opus Postumum, from the metaphysical doctrine of perceptible matter in motion to bodies subject to an a priori determinable system of forces.

And now Kant realizes that a question looms that will have made a reader of the Critique of Pure Reason and of the ensuing Metaphysical Foundations of Natural Science uneasy all along: However does a scientist get wind of this now systematically embodied nature? How does the subject come to know its now exhaustively knowable external object?

This realization brings on a pivotal moment in the later fascicles of the Opus Postumum, when the Selbstsetzungslehre, the “doctrine of self-positing,” comes to the fore. Again, Förster is a much-needed guide through the text.(101-116)

The terms of the first Critique are, all in all, well-marshalled—systematic and precise—within the work; it is when we think beyond it that they become scintillatingly obscure. We might worry that we are undercutting Kant’s explicit intention in thus thinking outside the box. The later Opus Postumum shows us Kant doing it himself. One might go so far as to say that the older he got the more radically he thought (which, rightly considered, is the way it ought to be).

The late work reconsiders self-consciousness, at first in the spirit of the Critique, but then in increasingly more boldly enunciated ways. Everything begins with “I think,” the self-recognition of the subject. It is a piece of mere logical analysis (since no intuition is involved) by which I make myself into an object to myself.(O.P. 182) So stated this first transcendental event makes me ask myself: Can so momentous a self-diremption, that of exercising my autonomy in making myself into my own object, occur by a merely logical act, the analysis of the meaning of “I think?” Doesn’t it require some ontological activity? Kant answers this question, though along Critical rather than metaphysical lines. The first act can occur only together with a second one: This is an act of synthesis, meaning one in which thought grasps and unifies something given that goes beyond mere logic—to begin with, pure time and space. In space and time the subject posits itself, or better the subject posits itself as an “I.” This is the doctrine of self-positing.

To appreciate how astounding this doctrine is we must look at the notion of positing. For Kant, to posit is to assign existence, the one and only way to realize existence (an identification that goes way back to an essay on the proofs of God’s existence of 1763). Thus in self-positing I bring myself into existence. It is an act of self-creation. This way of putting it tells me that existence is a subordinate condition depending on a somehow prior subject which is, however, itself not—or is not knowable as—a being that has an essence, an actuality, or, so far, personhood. The I-subject is a mystery into which Kant himself proscribes inquiry in his critique of dialectical reason.

So far, however, though I exist, I have not yet made it into the natural world. This is where the ether does its service. It makes space real to the senses, filled as it is with a universal proto-matter that is the condition of connected perceptions wherever I find myself in it. Space is thus not only the subjective form of sensation, but a real unified object outside me, unified by the ubiquitous presence of a weightless, unbulkable ether.

And yet I, in turn, am in it. For as space becomes perceptible because of the ceaseless dynamism of its system of ether-grounded forces, so I can perceive it since I myself am an organic body that is sensitive to forces because this body is itself a system of organized forces: To get sensation I must be sensitive, to get sensations from a dynamic system I must be such a system myself—I must be continuous with nature.

Here at last is the embodied subject in the world. Self-positing thus has a second phase. As I made myself exist within my pure cognitive constitution, so I posit myself as affected by forces that I have organized to enable me to experience nature: “Positing and perception, spontaneity and receptivity, the objective and subjective relations are simultaneous because they are identical as to time, as appearances of how the subject is affected—thus are given a priori in the same actus.”(O.P. 132) Förster observes that the last phrase means that the same original transcendental act brings about the duality of empirical self and material world. Because in apprehending the undetermined material manifold I insert into it certain fundamental forces I can simultaneously represent myself as an affected body and as so affected by an external cause.(107)

So it seems that the system finally has closed in on the human body from the inside out through the transcendental spatial intuition and from the outside in through the “hypostatized” forces of nature (meaning forces “supposed, but as real”): the elementary dynamical ether and the mechanical forces of physics known against its ethereal ground. Better late than never, though this body be merely a self-moving machine, which, incidentally, responds to impinging outside forces as would a system of rigid and moving parts. The subject has now called into existence not only itself but also its world and its body—has made itself aware of itself as a certified knower and simultaneously as a participating inhabitant of perceptible space. Perceptibility, however, is just what existence means for Kant: Existence is a by-product of the relation between a cognitive subject and the object it posits for itself, even outside itself. I would put the puzzle here thus: How real can such existence be, in the ordinary meaning of the word, that is, indefeasibly and self-assertively independent of me? Yet Kant would find, had found, such a question offensively obtuse since it voids the whole Critical enterprise and its compelling motives. Nonetheless, it does seem that in setting the limits of reason Kant has abolished the finitude of human autonomy, the finitude that implies something beyond me which I am not.

Förster interprets the doctrine of self-positing as a schema for (perceptible) outer space (114) since a schema brings together the spontaneous understanding with the receiving sensibility, in this case, matter-or sensation-filled space. This schema completes the conditions for a science of nature—though something else is missing.

There is as yet no personhood. But since persons are subjects to which deeds can be imputed, since they are moral, that is, free and responsible beings, and since one purpose of the whole enterprise was to ground human freedom and with it morality, Kant is driven to a second, a moral self-positing and, hard upon it, yet beyond, to a focusing of the idea of   God. More precisely, from the start of this final part of Kant’s last work these two topics, human morality and God, are more intimately related than they ever were in the Critique of Practical Reason. For there God is merely a postulate of practical reason,(2.2.5) a kind of by-thought, required because nature by herself offers no ground for assuring us of happiness commensurate with our deserts. So we must believe that there is a cause, working outside of nature, that will bring about such a reward. But the moral necessity of God is subjective, that is, it is a need, not an objective ground of duty or belief. In the Opus Postumum it is as if man, having brought himself, his world, and himself-in-the-world into existence, was now ready to posit God as well.

But there are more serious, systematic reasons for Kant to turn to God in his last work. The said postulate of the second Critique calls upon God as a condition of making moral actions achievable for humans. Förster traces the various functions God is assigned.(summarized on pp. 134-135) The last of these, stemming from Kant’s Religion within the Boundaries of Mere Reason (1793), is that of God as founder of an ethical commonwealth. But in the Opus Postumum Kant says repeatedly that the divine power cannot make a man morally good: “He must do it himself.”(O.P. 249) So here opens what Kant himself calls an “abyss of a mystery”; Förster interprets this phrase as Kant’s realization that human moral autonomy and God as founding father of an ethical commonwealth are in contradiction.(133) Kant finds a way out, adumbrated in Religion and sharpened in the late Opus Postumum.

The self-positing so far described had been theoretical, cognitive. But now Kant introduces a second, moral-practical self-positing, analogous to the first in having its own a priori moving forces: The ideas of right that unite all persons, as expressed in the Categorical Imperative (which commands, unconditionally, the subjection of individual inclination to laws acknowledged as universal, O.P. 198); the difference is only that the first involves being affected by outer, spatial forces, the second consists of obedience to one’s own rationality—self-forcing, one might say. Self-positing, recall, was bringing oneself into existence by becoming conscious at once of oneself as thinking and as being affected by objects determined by oneself. So too moral self-positing is self-consciousness together with the consciousness that I can subjugate my inclinations and can myself determine my will, that is, choose morally—which is what Kant calls freedom.

Kant now argues that the idea of human freedom, whose force is formulated in the Categorical Imperative, brings with it immediately, analytically, the concept of God. For the imperative is a command, which, like the law of a civil commonwealth, unites all rational beings, and therefore it requires a law-giver and enforcer. Thus God must exist, and to do as we ought (that is, our duty) is a divine command.

But God’s existence is not that of a being independent of human reason.(Förster 142) Rather just as we postulated an ether to make a system of forces possible, so we postulate God as real to give the idea of duty a moving force. Thus, the contradiction of human freedom and divine imposition certainly seems to be resolved.

Immanuel Kant

Immanuel Kant

There is one more step to be taken. God is now an ideal of practical reason, said, however, to exist—in some way. What is the divinity’s relation to nature, particularly human nature? This is Kant’s “abyss of a mystery,” mentioned above: God and the world are heterogeneous ideas; as God cannot make men better, for that would abrogate their moral freedom, so he cannot interfere with nature, for that would abrogate its lawful determinateness. Kant reaches for the solution we would now expect: The unification of God and nature lies in the human subject. It is to be found in “Man in the World, Restricting Himself Through Laws of Duty,” as the penultimate title page puts it.(O.P. 244) He is an ideal, an archetype; the wise man, the philosopher, who knows God in himself and the laws of nature and the imperative of action. Kant has been, significantly it now turns out, in the habit of using the term Weltweisheit, “world-wisdom,” for philosophy. With the human ideal, Kant has reached “The Highest Standpoint of Transcendental Philosophy.” Förster says he has therewith solved one of the oldest problems of philosophy: How to unify theoretical and practical reason.(146) And so he has—if we can comprehend this solution.

From Religion on through the Opus Postumum, Kant has been emphasizing the importance of a human ethical community, superintended by God to the realization of morality. In the latter work, it is this union of rational beings that makes the force of moral law analogous to the unifying ether of the natural system. Since now man has finally turned up in the body, a major enigma of the Critique of Practical Reason appears to be resolved: How transcendental subjects, each, moreover, locked within its own self-constituted natural world, can ever appear and speak to each other.

I say the enigma appears to be solved because the subject is now embodied and has material appearance. But that doesn’t really help: How does my appearing body enter your self-posited world—unless we hypostasize, very seriously, a true outside, a transcendent Beyond, through which I can come to you by infusing your intuition with a sensory manifold expressing my person in an appearance? But this is language so alien to Kant that I am almost abashed to use it. Nonetheless, the grounds of that intersubjective communication without which Kant cannot conceive an ethical community—a human one, at least—are missing from the Transcendental System. This enigma is clearly conjoined to that of another’s body, because before we apprehend each other as rational beings we must appear to each other as material bodies. For we have no way (short of entering each other’s minds) of conveying thought except in embodied form.

Nor is the God implied in our recognition of “human duties as divine commands” intelligible to me. This subjective God induces in me a desire to get down to brass tacks: Is a god who is “the inner vital spirit of man in the world”(O.P. 240) a God who exists in any ordinary sense, that is, a God who is a stand-alone substance, who is there, in his realm, whether I exist or not?

Kant refuted, more than once, Anselm’s proof that God exists (e.g., in the Critique Of Pure Reason B 626) because it depends on regarding existence not as the subject’s positing of an object but as a property of the object itself; thus Anselm argues that in conceiving God we must necessarily include his existence in his essence. Yet it seems to me that Kant has accepted a precondition of Anselm’s proof, namely that when thought necessarily conceives of (and therefore conceives necessarily) the object as existing, then it must exist—only where Anselm would say “beyond me,” Kant says “in my thought.” Is this an argument that gains anything as it goes? I think the final pages of his life’s work, preoccupied though it is with God-positing, show no sign that this question oppressed Kant, that he felt an insufficiency in the thought that the unifier of all realms is the dutiful man who has God within but is otherwise left on his own, is “his own originator”(O.P. 209) and also the maker of Heaven and Earth—except that once he says this: “There is a certain sublime melancholy in the feelings which accompany the sublimity of the ideas of pure practical reason.”(O.P. 212)

4. Here, to conclude, is a summary review of the perplexities that I found in the Critiques and of the bearing the Opus Postumum has on them.

First, the space puzzles. The Opus Postumum acknowledges what the transcendental Critiques had, ipso facto, no place for: that if the transcendental subject is to be affected by sensation through, or better, in its sensibility, it must be embodied. Kant now puts the subject’s body in space so that through its own forces it may interact with the forces of nature. This somatic positing quite literally fleshes out the system, and it does so by fixing on one of the several meanings of “external” that “outer sense” seems to carry in the first Critique: As one would expect, Kant now sometimes speaks as if the ether-filled space, where my body meets nature’s bodies, was in some real sense outside of myself as subject. That cannot be, however, since space never ceases to be what it was in the first Critique, the pure content (so to speak) of our receptive outer sense, the spatial intuition. But that fact results in this strangely involuted condition: The body, through which the world affects me, is within this Kantian sensorium, the intuition, the spatial sensibility; so we project a body within ourselves to receive sensations from an “outer” world we have ourselves created.(Kant’s own term, e.g., O.P. 235) I keep asking myself how Kant would have responded to this construal of the post-Critical layout. Would we could raise the dead!

On the second, more general, question concerning the origin and fixing of the transcendental terms that stake out the system, the Opus Postumum is silent, though Kant asks himself over and over what transcendental philosophy is—his very last proposed title (at least in Förster’s selection) is “Philosophy as a Doctrine of Science in a Complete System.” The question I am asking could be put like that: Where does the philosopher stand when he establishes “The Highest Standpoint of Transcendental Philosophy?” If Kant considered this question he does not say—perhaps he would have thought it madness—much as Aristotle thinks it is ridiculous to try to show that there is nature.(Physics 2.1)

The third question, “How is moral action actually inserted into a deterministic natural world?”—is in fact answered in the Opus: The rational subject exerts a moral force analogous to natural forces. But is it an answer? How exactly does the force of reason move bodies? Psychokinetically?

My fifth question, “Whence comes adventitious sensation and hence that contingency of nature which makes science empirical in detail?,” is simply and spectacularly untouched in the Opus Postumum, as it was in the Critiques. Yet it is not an unreasonable problem to raise, because, though Kant likes to describe what it is that comes to us as a mere “manifold” (manyness simply), sensation is in fact the material of specific appearances; hence, as it seems to me, some sort of evidence for its origin must be forthcoming (for from antiquity on, appearance is appearance of something, that is to say, is evidence and screen at once of something beyond it).

One motive for drawing sensation more and more into the subject is precisely the principled specification of natural science: The more detail comes under the subject’s control the more transcendentally grounded physics becomes, that is, the more it can anticipate its findings and make laws by analogy. As it is, the ether theory goes pretty far in prescribing, a priori, the types of mechanical force whose effects are to be noticed in bodies, even up to dictating some of their mathematical laws, for example the inverse square law of attraction: Kant explains that the following argument holds for any force that is diffused from the center of force through concentric spherical shells. Since the spherical surfaces vary as the square of their radii, the larger the sphere, that is the more distant from the center, the less will be the force distributed over each unit surface. Thus the effect of the force will vary inversely as the square of the distance or as 1/r².(Met. Found, 519)

Kants_Prolegomena_to_Any_Future_Metaphysics_1000064385Could it be that Kant might be driven to say that we ourselves are the creators of our sense material? In the Prolegomena to Any Future Metaphysics (1783) he distinguishes bounds that are positive in having an enfolding Beyond, from limits that are mere negations. In that work he says that metaphysics leads to bounds beyond which lie the “things in themselves,” which are inaccessible to experience and cognition because they are beyond our cognitive faculties, but which it is nonetheless necessary to assume as sources, presumably, among other things, of sensation.(57) In the Opus Postumum, that Beyond seems to have receded; then must we ourselves be the generators of sensation? Might we be driven to suppose that the unknowable transcendent nominal I is itself the source of the sensations that affect me? And if so, how is Kant’s system in that respect different from Fichte’s Science of Knowledge, in which the subject is completely self-posited, including its sensory affects, and of which Kant says that he regards it “as a totally indefensible system…for the attempt to cull a real object out of logic is a vain effort?”(O.P. 264) Call it absolute idealism or solipsism, in putting the world in man it leaves him solus, a subject alone without a confronting object, and Kant seems to find that insupportable in the Fichtean system. Recall from hints above that the first Critique itself was already vulnerable to the charge of solipsism. Sartre, for example, in the chapter “The Reef of Solipsism” in Being and Nothingness (3.1.2), raises it with respect to time, insofar as it is an inner sense: How then can a Kantian “I” be synchronous with any “Other?”

I want to insert a reflection here. Philosophers pride themselves on following wherever honestly consequential thinking leads, even into the insufferable. There came generations after Kant who took a kind of unholy joy in their desperate conclusions. But Kant is the philosopher of “conditions of possibility,” of finding the terms that enable the satisfaction of rational humanity. So I imagine him to be open to the question: Quo vadis?, “Where are you going?” For that the love of wisdom should turn out to be totally self-love seems indeed to be insufferable.

Finally, the sixth perplexity, the proof, no, rather the positing of the existence of God: In the first Critique the understanding, our faculty for organizing given material into experience, sets the starting terms; the theoretical reason is considered mainly as a faculty for attempting, indefeasibly, to marshal judgments connecting these terms into inevitably illusory syllogistic conclusions. In the Opus Postumum, however, the practical reason is paramount, for its requirements come to be dominant. It leads the way in the positing of self, body, and finally God. This God-positing is no longer the “as-if” postulation of Kant’s moral works, which entitles us to act merely as if there were a God who sanctions and rewards. In the Opus Postumum reason is compelled to posit God as actual—though in me and not as a substance. Actual though not substantial, subjective but an object—I seem to lack the intellectual wherewithal for entertaining these conjunctions. Indeed, one of the benefits of entering into the ratiocinative preoccupations of a Kant, who explores and pushes his own concepts to their limits and who is moreover—as I think—incapable of mere invention or simple confusion, is that one is confronted in precise and compelling terms with the limits of intelligibility.

5. The Kant we study as a community is and will continue to be the Kant of the two Critiques of Pure and Practical Reason, and so it will be, I think, for most students of philosophical works. Thus Kant’s influence on the thinking world (where attention to Kant is growing rather than waning, for example in cognitive science and in ethics) will be mostly Critical.

That Kant had a living post-Critical afterlife is in itself a source of fascination, which the review has tried to express. The Opus Postumum, however, though it may never, and probably should not, exert the direct influence of the Critiques, also contributes to Kant’s posthumous afterlife, not so much, as I said, in directly influencing the thinking of people now alive, as in projecting a drift that is being realized among us.

I am referring primarily to the topic of subjectivity. In many departments of life the outcome of a venture is an advance over the beginning—which is called progress. In philosophy, however, the working-out of the origin is often a shallowfication, to coin a term. One reason is precisely that philosophy is treated as progressive, which entails either contracting the deep open questions of original inquiry into more effectively resoluble tight problems, or, on the contrary, loosening the precisely significant terms of a coherent philosophy to connote its bowdlerized, or at least more relaxed, possibilities. Kant’s terms are more liable to the latter fate.

For Kant expands, late in life, and late in the Opus Postumum, on what he had asserted earlier: “Philosophy is to be regarded either as the habitus of philosophizing or as a work: through which there arises, proceeding from it, a work as a system of absolute unity.”(247; I can’t resist quoting a neighboring entry, which shows Kant in what he would call a “technical-practical” mode, that is, displaying mundane practicality—always an index of mental alertness: “N.B. The melon must be eaten today—with Prof. Gensichen—and, at this opportunity, [discuss] the income from the university.”) Consequently Kant’s terms are from the beginning well-defined and well-seated in a system, and thus apt to descend to the public by acquiring more diffuse rather than narrower usages.

System-building is out of style at the present moment; the mood is anti-foundationalist. Particularly out of favor in philosophy are the two great Critical assumptions, the one so deep beneath Kant’s thinking that there is no overt reflection on it in the Critiques, the other perhaps the central preoccupation of the Opus Postumum. The former is representationalism, the apprehension of thinking as the activity of putting objects before the cognitive faculties; the German for “representation” is Vorstellung, literally “setting [something] before [oneself].” (I should mention that representationalism at least is alive and well in the cognitive sciences, as opposed to philosophy.) The latter assumption is the one expressed in the quotation above, that the work of philosophy is “architectonic,” the building of a well-grounded, completely unified, and thoroughly detailed edifice representing the activities and aspects of the rational subject, the “I.” (To be sure, Kant’s system is only the penultimate great Continental system; in the ultimate one, however, that of Hegel, the dialectic of concepts supersedes representational thinking, and the system is not constructed architectonically but develops organically.)

Three hugely influential shapes that the “I” as an object of reflection has taken are: the Cartesian Ego, a thing that knows of its existence as it thinks and can apply itself to mathematicizable spatial extension; the Rousseauian Self, a pure interiority that knows and revels in its mere sense of existence; and a Kantian Subject, an I that knows itself in two capacities, as theoretical (the subject of formal thinking and of a formative sensibility which together give laws to external nature), and as practical (an autonomous person that gives the law to itself as a moral actor).

All three, Cartesian quantification, Rousseauian self-concern and Kantian personhood, have been absorbed and naturalized into contemporary thinking. The subject of the Critiques, however, being the most complex and comprehensive of these ideas, has also been most liable to second-hand connotations. For example, the word “subjective” evidently got into general philosophical and hence into common use through the Critiques, though when we say something is “purely subjective” we tend to mean it in a denigrating sense: lacking hard, public objectivity.

But the expanded terms of the Opus Postumum are not, as far as my reading goes, known to our contemporaries—the work has, after all, been available for barely a decade—neither to the proponents of human self- and world-construction nor to the post-Nietzschean value-relativists who hold some version of the idea that man himself is the creator of values, or the religious thinkers who regard God as a self-granted response to human need. Yet all these notions are in a more disciplined, systematic form adumbrated in the Opus Postumum: in the self-positing of the subject and its world-construction, in the autonomy of its moral life, and in the required postulation of its God.

But in what mode, to return to a question asked in the beginning, has Kant thus become the occulted projector of our modernity? Did he succumb—Förster thinks this implausible (76)—to the then-current craze of “posito-mania” (Setzkrankheit)? Is he spinning out the deep implications of the Critical enterprise, perhaps into originally unintended consequences and to his own uneasy amazement? Or has he, in adventurous old age, leapt beyond the Critiques into the stormy oceans that he once said surrounded the land of the pure understanding, an island of truth enclosed by the unchangeable bounds of nature?(Critique of Pure Reason, B 294)

These questions I am in principle unable to answer for myself because I am not sure whether there can be a philosophical system with joins so tightly fitted that its inherent necessities are unambiguously fixed, and in particular, because the transcendental system of the Opus Postumum offers surprises (the ether), superadded requirements (the specification of empirical physics), shortfalls of closure (the source of sensation). Nor am I certain in general whether, when a philosopher takes a structure of thought to a new level either by fine-tuning its technicalities or by driving it to its ultimate conclusions, he is doing the work of interpretation or of deconstruction. Instead I want to express this, my sense of Kant’s late unfinished work: If “awe” signifies a mixture of admiration and unease, here is the occasion to recall a good word to its proper use, and to say that the Opus Postumum is indeed awesome.

Books by Eva Brann may be found in The Imaginative Conservative Bookstore. This essay originally appeared in The St. John’s Review (Volume 47, No. 3, 2004) and is republished here with gracious permission. Miss Brann welcomes questions/comments via mail: Dr. Eva Brann, St. John’s College, 60 College Avenue, Annapolis, MD, 21401-1655 (she does not use computers).


Immanuel Kant. Opus Postumum. Edited with an Introduction and Notes by Eckart Förster. Translated by Eckart Förster and Michael Rosen. The Cambridge Edition of the Works of Immanuel Kant. Cambridge: Cambridge University Press, 1993.

Eckart Förster. Kant’s Final Synthesis: An Essay on the Opus Postumum. Cambridge, Mass.: The Harvard University Press, 2000.

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