Chapter 2. The Canon of Pure Reason
It is humbling for human reason that in its pure use it achieves nothing and even requires a discipline to rein in its extravagances and to prevent the illusions that befall it. Yet on the other hand this once again elevates reason and gives it a confidence in itself, that it can and must exercise this discipline of its own accord, without permitting any other censorship over itself; likewise that the boundaries it is compelled to set to its speculative use at the same time restrict the sophistical pretensions of every opponent, and can thereby secure against all attacks whatever might still remain to it of its formerly overblown demands. The greatest, and perhaps the only, utility that the entire philosophy of pure reason affords is thus in all likelihood merely negative: since it functions not as an organon for extension but as a discipline for fixing its limits, and, in place of uncovering truth, possesses only the unobtrusive merit of averting errors.
Yet there must, somewhere, be a wellspring of positive cognitions belonging within the province of pure reason, ones that perhaps occasion errors only by being misunderstood, though they truly make up the very aim of reason's zealous pursuit. For to what cause else should the insuppressible craving to gain a firm foothold somewhere entirely beyond the boundary of experience be ascribed? It has a presentiment of objects that carry with them a great interest of their own. To draw near to them it embarks on the route of mere speculation; but these take flight before it. Presumably better fortune is to be hoped for it upon the only path still left to it, namely that of practical use.
By a canon I mean the totality of the a priori principles for the proper employment of certain faculties of cognition as such. Accordingly, general logic, in its analytic portion, amounts to a canon for the understanding and for reason as such, though merely with respect to form, since it leaves all content out of account. In the same way, the transcendental analytic proved to be the canon of the pure understanding; for the understanding alone can achieve genuine synthetic cognitions a priori. Yet wherever no proper employment of a cognitive power is possible, no canon exists at all. Now, by every proof marshalled up to this point, pure reason in its speculative employment is wholly incapable of any synthetic cognition. There is therefore no canon whatever for its speculative employment (this being dialectical through and through); rather, in this regard the whole of transcendental logic is nothing more than discipline. Consequently, should there be anywhere a proper employment of pure reason — in which event a canon for it would likewise have to exist — such a canon will bear not on the speculative but on the practical use of reason, which we accordingly now propose to examine.
Section 1. On the ultimate end of the pure use of our reason
A propensity in its very nature drives reason to press beyond its use in experience, to hazard—in a pure use, and by way of mere ideas—an advance to the utmost limits of all cognition, and to come to rest only once its circuit is complete, in a systematic whole subsisting on its own. Now, is this striving founded merely upon reason's speculative interest, or instead wholly and only upon its practical one?
I shall leave aside for now the fortune that pure reason enjoys in its speculative undertaking, and inquire solely into those problems whose resolution constitutes its ultimate end—reach it or not—and beside which every other problem carries only the worth of a means. By the very nature of reason, these supreme ends will once more have to form a unity, so that the interest of humanity subordinate to no higher interest may be furthered as one.
The concluding aim at which reason's speculation, in its transcendental use, finally arrives bears on three objects: the will's freedom, the soul's immortality, and God's existence. As to all three, reason's purely speculative interest is but slight, and it is hardly for its sake that anyone would take up the exhausting toil of transcendental research, forever contending with obstacles, seeing that not one of the discoveries conceivably to be made here admits of a use that would demonstrate its worth in concreto, that is, within the study of nature. Grant that the will is free—even so, this can bear only on the intelligible cause of our willing. For where the phenomena of its manifestations are concerned, namely the actions, an inviolable ground-maxim—lacking which no reason could be exercised in an empirical use—obliges us to explain them exactly as we explain every other appearance of nature, that is, by nature's unchangeable laws. Suppose, secondly, that the soul's spiritual nature (and with it its immortality) admitted of insight—still, nothing can be built on this, neither as a ground of explanation touching the appearances of the present life, nor touching the special makeup of the state to come, for our concept of an incorporeal nature is nothing but negative, in no degree extending our cognition, and furnishing no serviceable material for inferences save such as could pass only as inventions, which philosophy disallows. Suppose, thirdly, that the existence of a supreme intelligence had been demonstrated: we would then indeed render comprehensible to ourselves the purposiveness in the world's contrivance and order taken generally, yet by no means be warranted to draw from it any specific institution and order, or, where such is not observed, to conclude to it audaciously; for a necessary rule of reason's speculative use forbids us to pass over natural causes and to relinquish what experience can teach us, so as to derive something we do know from what utterly exceeds all our acquaintance. In short, these three propositions stay, for speculative reason, transcendent throughout, and possess no immanent use whatever—none, that is, admissible for objects of experience and thereby in any manner useful to us—being rather, taken by themselves, wholly futile and, on top of that, extremely laborious strainings of our reason.
If, accordingly, these three cardinal propositions are in no way necessary to us for knowledge, and yet are pressed upon us insistently by our reason: then their significance can properly bear only on the practical.
Practical is whatever is possible through freedom. But when the conditions under which our free choice is exercised are empirical, reason can there have no use save a regulative one, serving merely to produce the unity of empirical laws; thus, for instance, in the doctrine of prudence reason's entire task lies in bringing together all the ends prescribed to us by our inclinations into the one end, happiness, and in making the means to it accord—so that reason can thereupon deliver no laws of free conduct except pragmatic ones, directed at attaining the ends the senses commend to us, and thus no pure laws determined wholly a priori. Pure practical laws, on the other hand—laws whose end reason supplies entirely a priori, and which do not command under empirical conditions but unconditionally—would be products of pure reason. Of just this sort are the moral laws; and so it is these alone that pertain to the practical use of pure reason and allow of a canon.
Thus the whole equipment of reason, in the enterprise one may name pure philosophy, is directed in truth only upon the three problems already considered. Yet these, for their part, look beyond themselves to a still more distant intent, namely what is to be done, supposing the will free, supposing there be a God and a world to come. Since what is here at issue is our behavior with a view to the highest end, the final purpose of the nature that so wisely provides for us, in fashioning our reason, is properly set upon the moral alone.
Caution, however, is called for: since we are turning our regard to an object foreign72 to transcendental philosophy, we must neither digress into episodes and so damage the unity of the system, nor, on the other side, by saying too little of this fresh material, let it come up short in distinctness or in conviction. I hope to achieve both by holding myself as closely as I can to the transcendental, and by putting wholly to one side whatever here might be psychological, that is, empirical.
And here the first thing to remark is that, for the present, I shall use the concept of freedom only in its practical sense, while the concept in its transcendental import—which cannot, as a ground of explanation of the appearances, be posited empirically, but is itself a problem for reason—I here set aside as already disposed of above. A power of choice, namely, is merely animal (arbitrium brutum) when nothing but sensible impulses can determine it, that is, pathologically. The power of choice, by contrast, that can be determined apart from sensible impulses, and thus by moving causes which reason alone represents, is termed free choice (arbitrium liberum); and whatever hangs together with it, be it as ground or as consequence, is called practical. Practical freedom can be proved through experience. For the human power of choice is determined not solely by what allures, that is, what affects the senses directly; rather, we possess a capacity to master the impressions on our sensible faculty of desire through representations of what, even in a more remote fashion, is beneficial or harmful; and these considerations of what is worth desiring with a view to our whole condition, that is, what is good and beneficial, rest upon reason. Reason accordingly issues laws too—imperatives, that is, objective laws of freedom—which pronounce what ought to happen, though perhaps it never does, and which are thereby marked off from laws of nature, whose sole concern is what does happen; and for this reason they are likewise named practical laws.
But whether reason itself, in these acts by which it prescribes laws, is not once more determined by influences of another kind, and whether what, with respect to sensible impulses, bears the name of freedom may not, with respect to higher and more remotely operating causes, once again be nature—that does not concern us in the practical domain, where we interrogate reason at first only for the precept of conduct; it is instead a purely speculative question, one we may lay aside so long as our concern is directed to acting or forbearing. Practical freedom, then, we come to know through experience as one among the natural causes, namely a causality that reason exercises in determining the will, while transcendental freedom asks for an independence of this reason itself (as regards its causality in beginning a series of appearances) from every determining cause of the sensible world, and to that extent appears to contradict the law of nature, and so all possible experience, thus remaining a problem. For reason in its practical use, however, this problem has no place; and so, within a canon of pure reason, we are occupied with just two questions bearing on the practical interest of pure reason, questions for which a canon of its use must be feasible, namely: is there a God? is there a life to come? The question regarding transcendental freedom touches merely speculative knowledge, and this we may set to one side as entirely a matter of indifference when the practical is at stake—a question, moreover, on which the antinomy of pure reason already affords discussion enough.
Section 2. On the ideal of the highest good, as a ground determining the ultimate end of pure reason
Reason, in its speculative employment, conducted us across the terrain of experience, and then—since it can nowhere find full satisfaction there—onward to speculative ideas; yet these in the end steered us back to experience once more, so that reason accomplished its purpose in a way that, however useful, fell quite short of what we had expected. One trial yet remains for us: whether pure reason may also be found at work in its practical employment; whether therein it conducts us to the ideas that reach those supreme ends of pure reason just enumerated above; and whether, viewed from the angle of its practical concern, it can after all bestow on us precisely what, on the speculative side, it denies us altogether.
Every concern of my reason, the speculative no less than the practical, converges upon the three following questions: 1. What can I know? 2. What ought I to do? 3. What am I permitted to hope?
The first of these is purely speculative. As I flatter myself, we have run through every answer that it admits of and have finally lit upon the one at which reason must indeed come to rest and, provided it keeps its gaze off the practical, has good ground to feel content; yet we stand as remote as ever from the two great ends at which this whole striving of pure reason was really aimed—as remote as if we had, from sheer love of comfort, refused the task at the very start. If, then, what we are after is knowledge, this much at any rate stands firm and beyond dispute: that in regard to those two tasks it can never become ours.
The second question is purely practical. As such a question it may well fall to pure reason, and yet in that case it is not transcendental but moral, so that it cannot be a business for our critique taken by itself.
The third question—namely, if I now do what I ought, what am I then entitled to hope? is at once practical and theoretical, in such a way that the practical merely serves as a thread by which we arrive at the theoretical, and, where this reaches high, the speculative question. For all hoping aims at happiness, and, as concerns the practical and the moral law, it is exactly what knowledge and the law of nature are as concerns the theoretical cognition of things. The former issues at last in the inference that something is (that which fixes the final possible end) because something ought to happen; the second, that something is (that which operates as supreme cause) because something happens.
Happiness is the gratification of all our inclinations (whether extensive, in respect of their manifoldness, or intensive, in respect of degree, or again protensive, in respect of duration). A practical law whose moving ground is happiness I term pragmatic (a rule of prudence); but one—should any such exist—that takes for its moving ground nothing beyond the worthiness to be happy I term moral (the moral law). The first counsels what must be done if we would have a share in happiness; the second dictates how we must bear ourselves so as merely to grow worthy of it. The first is founded on empirical principles; for apart from the mediation of experience I have no way of knowing either which inclinations exist that press for satisfaction, or what the natural causes are through which their satisfaction might be brought about. The second leaves out of account both the inclinations and the natural means of gratifying them, attending solely to the freedom of a rational being as such together with the necessary conditions under which that freedom, and it alone, accords with a distribution of happiness by principles, and therefore it can at the least rest upon bare ideas of pure reason and admit of being cognized a priori.
I take it that there genuinely exist pure moral laws which, wholly a priori (with no regard to empirical moving grounds, that is, to happiness), settle what is to be done and left undone, that is, govern how the freedom of a rational being in general is exercised, and that such laws command absolutely (not merely conditionally, on the supposition of further empirical ends) and are on that account necessary in every respect. This proposition I am entitled to lay down in advance, invoking not merely the demonstrations of the most enlightened among moralists, but the ethical judgment of any human being whatever, once he sets himself to conceive such a law with clarity.
Pure reason accordingly harbors—not in its speculative use, to be sure, but nonetheless in a certain practical, namely the moral, use—principles of the possibility of experience, that is, of such deeds as could, in keeping with ethical precepts, come to be found in the history of humankind. For inasmuch as it commands that such deeds ought to come about, they must also be capable of coming about, and hence a distinctive kind of systematic unity—the moral kind—has to be possible, while the systematic unity of nature could not be established on speculative principles of reason, since reason wields causality in the matter of freedom at large yet not in the matter of nature taken as a whole, and moral principles of reason are able to give rise to free deeds but not to laws of nature. In consequence, the principles of pure reason possess objective reality in their practical, and above all in their moral, use.
A world, to the extent that it should stand in accord with all ethical laws (as, by virtue of the freedom of rational beings, it can stand, and, by virtue of the necessary laws of morality, it ought to stand), I name a moral world. So far forth it is conceived merely as an intelligible world, because within it one leaves aside all conditions (ends) and even every impediment to morality therein (the frailty or impurity of human nature). To that degree, then, it is a mere idea, though a practical one, which really can and should exert its influence upon the sensible world, in order to bring the latter into accord with this idea as far as may be. The idea of a moral world therefore possesses objective reality, not as though it bore upon an object of some intelligible intuition (a thing we are wholly unable to conceive), but as bearing upon the sensible world—though as an object belonging to pure reason in its practical exercise and as a corpus mysticum of the rational beings within that world, in that their free choice, under moral laws, carries in itself a thoroughgoing systematic unity alike with its own self and with the freedom of each of the rest.
That constituted the reply to the earlier of the two questions that pure reason raised touching the practical concern: Do that through which you make yourself worthy to be happy. The second now inquires: given that I so bear myself as not to be undeserving of happiness, may I likewise hope by that means to become capable of sharing in it? Everything, in answering it, turns on whether the principles of pure reason that lay down the law a priori likewise bind up this hope with it of necessity.
My claim, then, is this: that precisely as the moral principles are necessary according to reason in its practical use, so it is no less necessary, according to reason in its theoretical use, to grant that each person has ground to hope for happiness to just the degree in which he has, by his conduct, rendered himself worthy of it, and hence that the system of ethical life is knit together with that of happiness indissolubly, though only within the idea of pure reason.
Now within an intelligible, that is, a moral, world—in the concept of which we set aside every impediment to ethical life (the inclinations)—such a system, wherein a proportioned happiness is joined to morality, admits of being thought as necessary as well, for freedom, in part impelled and in part curbed by ethical laws, would be the very source of the universal happiness, so that rational beings, guided by principles of this sort, would themselves author both their own lasting welfare and that of others at once. But this system of a self-recompensing morality is no more than an idea, the carrying-out of which hinges on the condition that each and all do as they ought—that is, that every deed of rational beings unfold as if it had issued from a sovereign will that gathers all private choice within or beneath itself. But since the bindingness that flows from the moral law holds good for every particular exercise of freedom, even where others should fail to conduct themselves in keeping with that law, nothing in the nature of the world's things, nor in the causality of the actions themselves and their bearing on ethical life, settles how their upshot will stand toward happiness; and the necessary linkage already noted—between the hope of being happy and the ceaseless endeavor to render oneself worthy of happiness—cannot be cognized by reason so long as one takes bare nature for one's foundation, but may only be hoped for once a supreme reason, commanding in accordance with moral laws, is taken as at the same time the ground of nature.
The idea of such an intelligence—one in which a will of the utmost moral perfection, conjoined with the highest bliss, is the origin of all the happiness in the world, so far as that happiness stands in precise proportion to ethical life (as the worthiness to be happy)—this idea I name the ideal of the highest good. Hence it is only within the ideal of that highest original good that pure reason can come upon the ground of the practically necessary linkage of the two constituents of the highest derived good—namely, an intelligible, that is, moral, world. Since we are now bound, through reason, to picture ourselves as belonging to such a world, even though the senses set before us nothing but a world of appearances, we shall have to take that world to be a sequel of our conduct in the sensible world and—because the latter presents us with no such linkage—to be a world still to come for us. God, then, and a life to come are two suppositions that, by the principles of that very reason, cannot be sundered from the bindingness which pure reason lays upon us.
Ethical life taken by itself makes up a system, but happiness does not, save to the extent that it is meted out in exact fitness to morality. This, however, is possible solely within the intelligible world, beneath a wise originator and governor. Reason finds itself constrained to assume such an originator, along with life in such a world—one we must look upon as yet to come—or else to treat the moral laws as hollow chimeras of the mind, since the necessary success that this same reason ties to them would inevitably lapse were that supposition wanting. This is likewise why everyone looks upon the moral laws as commands, which they could not be did they not, a priori, attach fitting consequences to their rule and thus carry promises and threats along with them. Yet even this they cannot do unless they have their seat in a necessary being—the highest good—that alone can make such a purposive unity possible.
Leibniz gave the world—so far as one heeds in it only the rational beings and their interconnection under moral laws beneath the government of the highest good—the name realm of grace, marking it off from the realm of nature, in which these same beings do indeed stand under moral laws yet look for no results of their conduct other than those that follow the ordinary course of nature in our sensible world. Thus to behold oneself within the realm of grace, where the whole of happiness lies in wait for us—save in so far as we ourselves cut down our share of it by an unworthiness to be happy—is an idea of reason that is practically necessary.
Practical laws, in so far as they come to be at the same time subjective grounds of the actions—that is, subjective principles—are termed maxims. The assessment of ethical conduct as to its purity and its consequences takes place by ideas; the following of its laws, by maxims.
It is necessary that the whole conduct of our life be placed under ethical maxims; and yet it is at the same time impossible for this to happen unless reason attaches, to the moral law—which is a bare idea—an operative cause that assigns to conduct governed by that law an outcome answering exactly to our highest ends, be it in this life or in some other. Absent a God, then, and a world unseen by us at present but hoped for, the splendid ideas of ethical life are indeed objects of applause and wonder, but not springs of resolve and performance, for they do not fulfil the whole end which is native to every rational being and which that very same pure reason fixes and makes necessary a priori.
Happiness on its own is, in the eyes of our reason, very far from the complete good. Reason gives it no sanction (however keenly inclination may crave it) so long as it is not wedded to the worthiness to be happy, that is, to good ethical conduct. But morality on its own, and with it the mere worthiness to be happy, likewise falls well short of being the complete good. For this to be brought to completion, whoever has borne himself as not undeserving of happiness must be in a position to hope for a share in it. Even a reason liberated from every private aim, were it—taking no interest of its own into the reckoning—to place itself in the position of a being charged with apportioning all happiness to others, could reach no other verdict; for in the practical idea the two components are bound together essentially, though in such wise that the moral disposition, functioning as condition, is what first makes possible the share in happiness, and not the reverse—that the prospect of happiness should be what first renders the moral disposition possible. For in the latter case it would fail to be moral, and hence unworthy also of that entire happiness which, in the sight of reason, acknowledges no restriction other than the one springing from our own unethical conduct.
Happiness, then, in precise commensuration with the ethical worth of rational beings, whereby they are worthy of it, is what alone makes up the highest good belonging to a world into which we are wholly obliged to transport ourselves by the precepts of pure yet practical reason—a world that is, admittedly, no more than intelligible, since the sensible world holds out to us, from the nature of things, no such systematic unity of ends, and whose reality can moreover be founded on nothing else than the supposition of a highest original good, wherein a self-standing reason, furnished with all the sufficiency of a supreme cause, in keeping with the most consummate purposiveness founds, sustains, and brings to completion the universal order of things, though one hidden deep from us in the sensible world.
This moral theology enjoys, now, the singular advantage over the speculative kind that it leads without fail to the concept of a single, most perfect of all, and rational primordial being—something toward which speculative theology, arguing from objective grounds, does not so much as direct us, still less could it persuade us of it. For neither in transcendental nor in natural theology, however far reason may carry us within them, do we come upon any weighty ground for positing so much as a single being that we might set over all natural causes and upon which we might have cause enough to make those causes dependent through and through. If, on the other hand, we weigh—from the vantage of ethical unity as a necessary law of the world—the cause that can lend this unity its fitting effect and therewith a force binding upon us, then it must be one sole supreme will that holds all these laws together within itself. For how could a complete unity of ends ever be found among a plurality of wills? This will must be all-powerful, so that the whole of nature, together with its bearing on ethical life in the world, may lie subject to it; all-knowing, so that it may cognize the inmost of the dispositions and their moral worth; everywhere present, so that it may stand immediately near to every need that the world's supreme good demands; everlasting, so that at no time may this concord of nature and freedom fall short, and so on.
But this systematic unity of ends within the said world of intelligences—which, taken as mere nature, amounts only to a world of sense, whereas as a system of freedom it may be styled an intelligible, that is, moral, world (regnum gratiae)—leads without fail to a purposive unity of all the things that compose this vast whole by universal laws of nature, exactly as the former unity does by universal and necessary ethical laws, and it fuses practical reason with the speculative. The world must be pictured as having sprung from an idea, if it is to fall into accord with that employment of reason apart from which we should count ourselves unworthy of reason—namely the moral employment, resting as it does wholly on the idea of the highest good. By this means every inquiry into nature receives a bent toward the form of a system of ends, and, at its widest reach, turns into physico-theology. This latter, however—since it set out, after all, from ethical order as a unity grounded in the very essence of freedom and not contingently instituted by outward commands—carries the purposiveness of nature back to grounds that must be a priori and inseparably tied to the inner possibility of things, and thereby to a transcendental theology which fastens upon the ideal of the highest ontological perfection as its principle of systematic unity—a principle binding all things by universal and necessary laws of nature, since one and all they take their origin in the absolute necessity of a single primordial being.
What use are we to make of our understanding, even where experience is concerned, if we set ourselves no ends? But the loftiest ends are those of morality, and these it is pure reason alone that can bring us to cognize. Equipped with these ends now and led by their thread, we can put the knowledge of nature itself to no purposive use as regards cognition wherever nature has not herself laid down a purposive unity; for lacking this we should not so much as possess a reason of our own, since we would be without any school for it and without any cultivation by way of objects that might furnish the material for concepts of the kind. That purposive unity, however, is necessary and takes its ground in the very essence of free choice, and so the latter—holding, as it does, the condition for applying that unity in concreto—must be necessary too; and thus the transcendental heightening of our rational cognition would prove to be, not the cause, but merely the effect of the practical purposiveness that pure reason lays upon us.
We therefore likewise discover, in the history of human reason: that until the moral concepts had been purified and made determinate enough, and until the systematic unity of ends conforming to them had been grasped—and grasped, indeed, from necessary principles—the knowledge of nature, and even a respectable degree of cultivation of reason across a number of other sciences, was able in part to bring forth none but crude and roving concepts of the deity, and in part left standing an astonishing indifference toward this question altogether. A fuller working-out of moral ideas, rendered necessary by the utterly pure moral law of our religion, whetted reason upon the object through the interest it obliged reason to take therein; and without any contribution either from an enlarged acquaintance with nature or from sound and trustworthy transcendental insights (of which sort there has at every period been a dearth), these ideas brought to pass a concept of the divine being that we now regard as the right one—not because speculative reason persuades us of its rightness, but because it chimes perfectly with the moral principles of reason. And so, when all is said, it is ever only pure reason, though solely in its practical employment, that has the credit of binding to our highest concern a cognition which bare speculation may merely surmise yet cannot make good, and of thereby raising it—not, to be sure, into a demonstrated dogma, but nonetheless into a wholly indispensable supposition attaching to reason's most essential ends.
But now that practical reason has attained this lofty vantage—the concept, namely, of a single primordial being as the highest good—it may in no way take the liberty, as though it had lifted itself above all the empirical conditions of that concept's application and soared up to an immediate acquaintance with fresh objects, of setting out from this concept and deducing the moral laws themselves from it. For it was these very laws whose inner practical necessity drove us to the supposition of a self-standing cause, or of a wise governor of the world, so as to lend those laws effect; and for that reason we cannot, following upon this, turn round and regard them as contingent and drawn from a mere will—least of all from a will of which we should have no concept whatever, had we not shaped it in conformity with those very laws. So far as practical reason is entitled to lead us, we shall deem actions binding not on the ground that they are God's commands, but shall instead look on them as divine commands on the ground that we stand inwardly bound to them. We shall study freedom beneath the purposive unity by the principles of reason, and shall believe ourselves in accord with the divine will only to the extent that we hold sacred the moral law which reason teaches us out of the very nature of actions, and shall believe that we serve that will by this alone—that we further the world's good in ourselves and in others. Moral theology is thus of an immanent use only—namely, to discharge our vocation here in the world by fitting ourselves into the system of all ends—and not, in a rapturous or perhaps even sacrilegious spirit, to forsake the thread of a morally legislative reason within a good course of life in order to tie it directly onto the idea of that highest being—an idea whose adoption would furnish a transcendent use that, just like the use of bare speculation, cannot but pervert and thwart the ultimate ends of reason.
Third Section. On opining, knowing, and believing
Assent is an event within our understanding, one that may indeed rest on objective grounds while also requiring subjective causes in the mind of whoever is judging. Should it hold good for everyone, so far as he but possesses reason, then its ground is objectively sufficient, and the assent is at that point termed conviction. Should its ground lie merely in the special character of the subject, it is termed persuasion.
Persuasion is nothing but a semblance, since the ground of the judgment, residing purely in the subject, is held to be objective. For that reason such a judgment likewise carries only private validity, and the assent admits of no communication. Truth, by contrast, reposes on accordance with the object, in regard to which the judgments of every understanding must accordingly agree (consentientia uni tertio consentiunt inter se). Whether an assent amounts to conviction or to mere persuasion has, then, its outward touchstone in whether it can be shared and found valid for the reason of every human being; for at that point there is at any rate a surmise that the ground of the concurrence of all judgments, in spite of the differences among the subjects themselves, will lie in the common ground, that is, the object, with which they therefore one and all harmonize and so establish the truth of the judgment.
Persuasion, then, admittedly cannot be told apart subjectively from conviction whenever the subject keeps the assent in view merely as an appearance of its own mind; yet the trial one runs by applying the grounds of it, valid for us, to the understanding of another—to see whether upon a foreign reason they work exactly the effect they work upon ours—is nonetheless a means, subjective though it remains, not indeed of producing conviction, but of laying bare the sheer private validity of the judgment, that is, something in it that is nothing but persuasion.
If, over and above this, we are able to unfold the subjective causes of the judgment that we mistake for its objective grounds, and can thereby account for the deceptive assent as an event in our mind without requiring for it the character of the object: then we strip the semblance bare and are on that account no longer taken in, though still to some degree tempted so long as the subjective cause of the semblance cleaves to our nature.
I am able to assert nothing—in other words, to enunciate as a judgment binding for everyone of necessity—save what produces conviction. A persuasion I may retain for myself if I find it agreeable, yet I can neither, nor ought I to wish to, make it count outside myself.
Assent, or the subjective validity of a judgment in relation to conviction (which holds objectively at the same time), possesses the following three grades: opining, believing, and knowing. Opining is an assent consciously deficient both subjectively and objectively. Where the latter is merely sufficient subjectively while being reckoned objectively deficient, it bears the name believing. Lastly, an assent sufficient subjectively as well as objectively bears the name knowing. Sufficiency on the subjective side is termed conviction (for myself), sufficiency on the objective side certainty (for everyone). I shall not linger over the clarification of concepts as easy to grasp as these.
I dare never presume to opine unless I know at least something whereby the judgment, in itself no more than problematic, gains a link with truth which, incomplete though it be, still amounts to more than a capricious fabrication. Beyond this, the law governing such a link must be certain. For if in regard to it I too have nothing beyond opinion, then the whole is but a game of imagination lacking the least bearing on truth. Within judgments drawn from pure reason there is no leave whatever to opine. For inasmuch as they draw no support from grounds of experience but everything is meant to be cognized a priori, where all is necessary, the principle of the linkage calls for universality and necessity, and thus for entire certainty, in default of which no lead toward truth is to be had at all. Hence it is preposterous to opine in pure mathematics; one must know, or else abstain from judging altogether. Matters stand the same way with the principles of morality, since one dare not risk an action on the bare opinion that something is permitted, but has to know it.
In the transcendental employment of reason, on the other hand, opining is naturally too meager, yet knowing likewise too much. With a purely speculative aim, then, we cannot judge here at all: for subjective grounds of assent, such as can bring about belief, merit no approbation in speculative questions, since they neither keep themselves clear of every empirical aid nor allow of being conveyed to others to the same degree.
It is solely within a practical relation, however, that a theoretically deficient assent can ever be called belief. This practical aim is now either the aim of skill or that of morality, the former bearing on arbitrary and contingent purposes, the latter, however, on purposes utterly necessary.
The moment an end is laid down, the conditions for reaching it become hypothetically necessary. This necessity is subjective, yet no more than comparatively sufficient, in case I am aware of no other conditions whatever under which the end might be reached; but it is unqualifiedly and universally sufficient once I know for certain that no one could be acquainted with other conditions leading to the end laid down. In the former case my supposition, together with the assent to certain conditions, is a merely contingent belief, whereas in the latter it is a necessary one. A physician confronted with a patient in danger has to do something, yet does not recognize the disease. He attends to the symptoms and concludes, for want of anything better, that it is consumption. His belief is, even by his own verdict, merely contingent; someone else might well hit the mark more accurately. Such contingent belief, which nevertheless underlies the real employment of the means toward certain actions, I call pragmatic belief.
The customary touchstone for telling whether what someone maintains is bare persuasion, or at any rate subjective conviction—that is, firm belief—is wagering. Not seldom a person delivers his propositions with so assured and intractable an obstinacy that he appears to have shed every worry about error. A wager pulls him up short. At times it emerges that his persuasion, while worth staking a single ducat, does not extend to ten. The one he will still hazard readily enough, but faced with ten he suddenly grows aware of what had escaped him before, namely that he may, after all, quite possibly have gone wrong. Let a person picture to himself that he is to wager the fortune of his entire life upon it, and his triumphant verdict shrinks drastically, he turns exceedingly diffident, and only then does it dawn on him that his belief does not carry so far. Pragmatic belief, accordingly, has but a degree, which—depending on how large the interest in play may be—can prove great or else small.
But since—granting that we can set nothing whatever afoot with respect to an object, so that the assent stays merely theoretical—we can nonetheless in many instances entertain and picture an enterprise for which we fancy ourselves to hold adequate grounds, supposing there were some means of settling the certainty of the thing, there arises in purely theoretical judgments an analogue of practical ones, to whose assent the word belief is suited, and which we may christen doctrinal belief. Were it feasible to settle the point through any experience at all, I would readily stake everything I own upon it that inhabitants exist on at least one or another of the planets within our sight. For that reason I declare it to be no mere opinion but a robust belief (on whose rightness I would already hazard many of life's benefits) that dwellers in other worlds exist as well.
We must now own that the doctrine of God's existence pertains to doctrinal belief. For although, as regards the theoretical knowledge of the world, I have nothing to dispose of that would of necessity presuppose this thought as a condition of my explanations of the world's appearances, being obliged rather to employ my reason as though everything were mere nature: the purposive unity is for all that so weighty a condition of the application of reason to nature that I—experience furnishing me, besides, abundant instances of it—can by no means pass it over. For this unity, however, I am acquainted with no other condition that would render it my clue for the study of nature than to presuppose that a supreme intelligence has arranged all things after the wisest ends. It follows that presupposing a wise author of the world is a condition of an aim which, though contingent, is nonetheless far from trivial—namely, that of having a guide in the investigation of nature. The upshot of my inquiries so frequently corroborates the serviceability of this presupposition, while nothing can be brought decisively against it, that I would be saying far too little were I to call my assent a mere opining; rather, even within this theoretical bearing it may be said that I steadfastly believe in a God; yet in that case this belief, taken strictly, is nonetheless not a practical one, but has to be termed a doctrinal belief, such as the theology of nature (physico-theology) must of necessity generate at every turn. In view of that very wisdom, considering the superb outfitting of human nature together with the shortness of life so ill-fitted to it, there is likewise ample ground to be met with for a doctrinal belief in the future life of the human soul.
In such cases the profession of belief is a profession of modesty on the objective side, yet at once of steadfast confidence on the subjective. Were I to call the merely theoretical assent here so much as a hypothesis that I should be entitled to adopt, I would thereby be pledging myself already to command a fuller concept of the makeup of a world-cause and of another world than I am truly able to set forth; for of anything I adopt even only as a hypothesis I must be acquainted at least with enough of its properties that I may fabricate not its concept but only its existence. The word belief, however, bears solely upon the guidance an idea affords me and upon the subjective influence toward furthering my operations of reason, which keeps me holding fast to that idea, even though I am unable to render account of it with a speculative aim.
But merely doctrinal belief harbors something wavering in itself; one is often unseated from it by difficulties cropping up in speculation, though one unfailingly comes back to it time and again.
With moral belief the case stands quite differently. For here it is downright necessary that something come to pass, namely that I render obedience to the moral law in every particular. The end is here fixed beyond escape, and by all my insight only one solitary condition is possible under which this end hangs together with the sum of all ends and thereby holds practical validity—namely, that a God and a world to come exist; I know, moreover, with full certainty that no one is acquainted with other conditions conducting to the same unity of ends beneath the moral law. But since, then, the moral precept is at once my maxim (reason, indeed, enjoining that it be so), I shall unfailingly believe in an existence of God and in a life to come, and I rest assured that nothing can set this belief tottering, seeing that thereby my very moral principles would be toppled, principles I cannot forswear without becoming loathsome in my own eyes.
In this manner, once all the ambitious designs of a reason roving past the frontiers of every experience have been thwarted, there yet remains enough for us to have reason to rest content with it for practical purposes. Admittedly no one, to be sure, will be in a position to plume himself that he knows there to be a God and there to be a life to come; for if he knows this, he is precisely the man I have long been in search of. Every piece of knowledge (where it concerns an object of mere reason) admits of communication, and I might therefore even hope, through his tuition, to behold my own knowledge stretched to so marvelous an extent. No—the conviction is not a logical but a moral certainty, and because it reposes on subjective grounds (those of the moral cast of mind), I must not so much as declare: it is morally certain that a God exists, etc., but instead: I am morally certain, etc. Which is to say: my belief in a God and in another world is woven together with my moral cast of mind so tightly that, just as little as I stand in danger of forfeiting the latter, so little do I fear that the former could ever be torn from me.
The one misgiving that presents itself in all this is that this belief of reason props itself upon the presupposition of moral dispositions. Should we set this aside and take up someone utterly indifferent toward moral laws, then the question reason throws up turns into a mere problem for speculation and can at that point be shored up, to be sure, with forceful grounds drawn from analogy, yet not with such as the most obstinate craving for doubt would have to yield to.73 There is, however, no human being free of all interest where these questions are concerned. For though a lack of good dispositions may sever him from the moral, still even in this case enough is left over to make him dread a divine existence and a hereafter. For nothing further is called for here than that he be at the very least incapable of pretending to any certainty that no such being and no life to come are to be found—which, since it would have to be proved by pure reason and thus apodictically, would oblige him to establish the impossibility of both, a thing that assuredly no reasonable person can shoulder. This would be a negative belief, one able to bring about not indeed morality and good dispositions, but nonetheless the analogue of them—that is, forcibly to hold in check the eruption of the evil ones.
But is this the whole of it, someone will say, that pure reason brings off in throwing open vistas past the bounds of experience? no more than a pair of articles of belief? So much as this even ordinary understanding could well have brought off, without calling the philosophers into consultation over it!
I have no wish here to vaunt the merit that philosophy possesses, through the toilsome exertion of its critique, on behalf of human reason; suppose its issue were even found to be merely negative; for something on that head will still come up in the following section. But do you really insist that a cognition bearing on all human beings should outstrip ordinary understanding and be unveiled to you by philosophers alone? This very thing you find fault with is the finest corroboration of the soundness of the assertions advanced hitherto, inasmuch as it brings to light what could not be foreseen at the outset—namely, that nature, in matters of concern to human beings without distinction, is not to be accused of any partial parceling out of her gifts, and that the loftiest philosophy, when it comes to the essential ends of human nature, can carry things no further than the guidance she has vouchsafed even to the most ordinary understanding.
Chapter 3. The Architectonic of Pure Reason
What I mean by an architectonic is the art proper to systems. It is systematic unity that first elevates ordinary cognition into a science — that turns a mere aggregate of it into a system — and for this reason the architectonic is the teaching about whatever is scientific in our cognition taken as a whole, so that it belongs of necessity to the doctrine of method.
Where reason holds sway, our cognitions are not permitted to form any rhapsody whatever; they are required instead to make up a system, since only within one can they lend support to reason's essential ends and carry them forward. And by a system I mean the unity of manifold cognitions brought together under one idea. Such an idea is the rational concept of the form of a whole, to the extent that this concept fixes a priori both how far the manifold extends and where the several parts stand in relation to one another . Hence this scientific concept of reason holds within it the end together with the form of that whole which answers to it. Because the end is one — and all the parts refer to it, and, within its idea, to one another as well — it comes about that any part may be found wanting once the others are known, and that no chance addition occurs, nor any indeterminate magnitude of perfection lacking the boundaries fixed for it a priori. The whole is therefore jointed (articulatio) rather than piled up (coacervatio); it may grow from within (per intussusceptionem), though never from without (per appositionem), just as an animal body grows without gaining a single limb, its growth leaving the proportions untouched while rendering each part stronger and fitter for its ends.
To be carried out, the idea stands in need of a schema, that is, of an essential manifoldness and arrangement of the parts, both fixed a priori out of the principle of the end. Where a schema is sketched not from an idea — that is, not from reason's principal end — but empirically, following intentions that happen to turn up (whose sum no one can foresee), it delivers technical unity; where, by contrast, it springs solely in consequence of an idea (reason here assigning the ends a priori rather than waiting on experience for them), it founds architectonic unity. What we name a science can arise not technically — through some resemblance among the manifold, or through a chance employment of cognition in concreto toward any external ends one pleases — but only architectonically, by virtue of the kinship and the descent from one sole supreme and inner end that alone renders the whole possible; and the schema of such a science must set out the contour (monogramma) as well as the partition of the whole into members conformably to the idea, that is, a priori, and must mark it off with certainty and on principles from all the rest.
No one sets out to establish a science unless some idea underlies his effort. Yet as he works it out, the schema — indeed even the definition he offers of his science at the very start — seldom matches his idea; for the idea rests in reason after the fashion of a seed, within which every part still lies tightly folded and so hidden as to be barely discernible even under microscopic scrutiny. On that account, seeing that all sciences are conceived from the vantage of some general interest, one ought to expound and delimit them not by the description their originator supplies of them, but by the idea that one discovers grounded in reason itself, an idea drawn from the natural unity of the parts he has brought together. For it will emerge in that case that the originator, and frequently his latest heirs as well, grope about an idea they have never managed to make plain to themselves, and are therefore unable to pin down the distinctive content, the articulation (systematic unity), and the limits of the science.
It is a sorry thing that only once we have, over a long stretch and at the prompting of an idea concealed within us, gathered up in rhapsodic fashion a mass of pertinent cognitions to serve as building stock — indeed only once we have for lengthy spans of time fitted them together technically — does it at last become possible for us to catch sight of the idea in a brighter light and to lay out a whole architectonically in keeping with the ends of reason. Systems have the look of worms, sprung by a generatio aequivoca from the sheer running-together of amassed concepts — misshapen at first and, with time, brought to completion — even though one and all they held their schema as the original seed within a reason that merely unfolds itself, so that each is not only jointed on its own according to an idea, but the whole set are, beyond that, joined purposefully to one another, standing once more as limbs of one body within a system of human cognition, and thus make room for an architectonic of all human knowledge which, in our own day — when material lies gathered already in such quantity, or may be retrieved from the rubble of old edifices that have caved in — would prove not merely attainable but hardly even difficult. For our part we rest content with finishing the task before us, which is simply to lay out the architectonic of all cognition that issues from pure reason, and we take our start only from that juncture at which the common root of our cognitive power splits and sends up two trunks, one being reason. Here, though, by reason I mean the whole of the higher faculty of cognition, thereby setting the rational over against the empirical.
Should I set aside the entire content of cognition, regarded objectively, then, on the subjective side, all cognition is either historical or rational. Historical cognition amounts to cognitio ex datis, the rational to cognitio ex principiis. However a cognition may first have been supplied, and from whatever quarter, it remains, for whoever holds it, historical, provided he cognizes only to the measure and the amount handed to him from without; and this handing-over may reach him through firsthand experience, through report, or else through instruction (in general cognitions). Thus a man who has genuinely learned a philosophical system — the Wolffian, say — even were he to carry in his head all its principles, its explications and demonstrations, along with the layout of the entire doctrinal structure, and could tick every item off on his fingers, still possesses none but a complete historical cognition of the Wolffian philosophy; he knows and adjudges no more than was consigned to him. Let a definition be contested against him, and he is at a loss where to procure another. He shaped himself upon another's reason, yet the faculty that copies is not the faculty that generates — that is, in him the cognition did not well up out of reason — and although objectively it was indeed a cognition of reason, on the subjective side it stays merely historical. He apprehended well and held fast, that is, he learned, and he is a plaster impression taken from a living man. Cognitions of reason that are so objectively (in that they can, to begin with, well up only from the human being's own reason) are entitled to carry this name subjectively too, but only where they have been drawn from reason's universal wellsprings — the very source from which criticism, and even the repudiation of what was learned, may equally proceed — in short, from principles.
Every cognition of reason is at this point either one derived from concepts or one derived from the construction of concepts; the first we term philosophical, the second mathematical. The inner difference between the two I have already dealt with in the first chapter. A cognition may thus be philosophical objectively and yet historical subjectively, as happens with the majority of pupils and with all who never look past the schoolroom and stay pupils for life. It is curious, all the same, that mathematical cognition, precisely as one has picked it up, can pass subjectively for cognition of reason as well, so that the sort of split found in the philosophical case does not arise for it. The reason lies in this: the springs of cognition on which the teacher alone can draw are situated nowhere but in the essential and authentic principles of reason, and so cannot be fetched by the pupil from any other quarter, nor indeed contested; and this holds because here reason is exercised only in concreto, yet still a priori — namely upon the pure and for that very reason faultless intuition — and thereby shuts out all illusion and error. Among all the rational sciences (a priori), then, mathematics alone can be learned, philosophy never (save historically); where reason itself is concerned, the most one can learn is to philosophize.
The system embracing all philosophical cognition is precisely philosophy. One is bound to take it objectively when one means by it the prototype against which every attempt at philosophizing is to be measured, a prototype serving to appraise each subjective philosophy, whose structures are so often varied and so often shifting. Taken this way, philosophy is a mere idea of a science that might be, nowhere handed to us in concreto, though one strives to draw near it along sundry routes until the sole footpath — badly overgrown by sensibility — comes to light and the hitherto botched copy is made, so far as is granted to human beings, to match the prototype. Until that point no philosophy can be learned; for where does it reside, who has it in hand, and by what marks is it to be known? One can learn only to philosophize — that is, to train reason's talent by having it follow its universal principles across certain attempts already at hand, though always keeping in reserve reason's right to probe those principles at their sources and to uphold or discard them.
Up to that point, however, the concept of philosophy is nothing beyond a scholastic concept, namely of a system of cognition pursued solely as a science, aiming at nothing further than the systematic unity of this knowledge and thus at the logical completeness of cognition. But there is besides a cosmic concept (conceptus cosmicus) that has at all times lain beneath this label, above all whenever one personified it, as it were, and pictured it as a prototype in the ideal of the philosopher. On this understanding, philosophy is the science that treats how all cognition bears on the essential ends of human reason (teleologia rationis humanae), and the philosopher is no craftsman of reason but the lawgiver of human reason. In that sense it would be great presumption to style oneself a philosopher and to lay claim to having matched the prototype, which resides in the idea alone.
The mathematician, the natural scientist, the logician — however splendid the progress the former may make in cognition of reason at large, and the latter above all in philosophical cognition — remain for all that mere craftsmen of reason. There is besides a teacher in the ideal who deploys them all, turning them into tools for advancing the essential ends of human reason. Him alone ought we to call the philosopher; but since he is nowhere to be encountered, while the idea of his lawgiving is encountered everywhere, in every human reason, we shall confine ourselves to the latter and settle more closely what systematic unity philosophy, taken by this cosmic concept,74 lays down from the vantage of ends.
Essential ends are not on that account already the highest, of which (once reason attains perfect systematic unity) there can be but one. They are accordingly either the final end or subordinate ends that necessarily attach to it as means. The former is nothing else than the whole vocation of the human being, and the philosophy bearing on it we call morals. Because of this precedence that moral philosophy enjoys over every other pursuit of reason, the ancients too, under the name of philosopher, always meant at once and by preference the moralist; and even now the outward appearance of governing oneself through reason is what leads us, by a kind of analogy, to call a person a philosopher despite the narrowness of his knowledge.
The lawgiving of human reason (philosophy) has, then, two objects, nature and freedom, and so comprises the law of nature no less than the law of morals — housed first in two distinct systems, but in the end within one philosophical system alone. The philosophy of nature reaches to all that is, that of morals only to what ought to be.
All philosophy, though, is either cognition sprung from pure reason or cognition of reason resting on empirical principles. The first we call pure philosophy, the second empirical.
The philosophy of pure reason is now either propaedeutic (a preparatory drill), which examines reason's capacity with regard to all pure cognition a priori and bears the name critique, or, secondly, the system of pure reason (as a science), the entire body of philosophical cognition from pure reason — true and apparent alike — in systematic coherence, bearing the name metaphysics; though this last name may equally be conferred on the whole of pure philosophy, critique included, so as to gather up both the inquiry into everything that can ever be cognized a priori and the exposition of whatever makes up a system of pure philosophical cognitions of this sort, marked off, however, from all empirical and likewise from the mathematical use of reason.
Metaphysics splits into a metaphysics of the speculative and one of the practical use of pure reason, and is thus either a metaphysics of nature or a metaphysics of morals. The former holds all the pure principles of reason drawn from concepts alone (mathematics thereby excluded) that govern the theoretical cognition of all things; the latter holds the principles that fix what is to be done and left undone a priori and render it necessary. Now morality is the sole conformity-to-law of actions that admits of being derived wholly a priori from principles. The metaphysics of morals is therefore, strictly, pure morality, one that rests on no anthropology (no empirical condition) as its foundation. The metaphysics of speculative reason is what one customarily labels metaphysics in the narrower sense; but since pure moral doctrine belongs nonetheless to that special stem of human — indeed philosophical — cognition out of pure reason, we mean to keep that title for it, even while we set it aside here as not pertaining to our purpose just now.
It matters in the highest degree to isolate cognitions that stand apart from others in kind and in origin, and to take careful precaution that they do not merge into a blend with those to which, in use, they are ordinarily tied. What the chemist does in parting substances, and the mathematician in his pure theory of quantity, falls upon the philosopher still more heavily, so that he may pin down with assurance the portion that a distinct species of cognition contributes to the stray use of the understanding, and thereby its peculiar worth and influence. For this reason human reason, ever since it began to think — or rather to reflect — has at no time gone without a metaphysics, and yet has never been able to set it forth cleansed sufficiently of everything alien to it. The idea of a science of this kind runs back as far as speculative human reason itself; and what reason does not speculate, be it in a scholastic or in a popular vein? One must grant, meanwhile, that the separation of the two elements of our cognition — the one sort wholly within our command a priori, the other to be had only a posteriori from experience — stayed exceedingly murky even among thinkers by trade, and could on that account never accomplish the bounding-off of a distinct species of cognition, and hence never the genuine idea of a science that has so long and so keenly engaged human reason. Were one to say that metaphysics is that science which handles the first principles of human cognition, one would thereby single out not a wholly distinct species but merely a rank as regards generality, so that on this footing it could not be told apart in any recognizable way from the empirical; for among empirical principles too some are broader and hence loftier than others; and along the sequence of such a subordination (given that one does not part what is wholly a priori from what is cognized only a posteriori): at what point is the cut to be made that would sever the first portion and the topmost members from the last and the ones ranked beneath? What would be said if chronology could mark off the epochs of the world only in this manner, that it divided them into the first centuries and those coming afterward? Does the fifth, the tenth, etc. century likewise count among the first? one would ask; and in the same way I ask: Does the concept of the extended fall under metaphysics? You reply: Yes! Ah, but that of body as well? Yes! And that of the fluid body? You falter, for if things run on in this way, then everything will fall under metaphysics. From this it is plain that the bare degree of subordination (the particular set beneath the general) cannot mark out the boundaries of a science, but rather, in our case, the utter dissimilarity and diversity of origin. What further clouded the root idea of metaphysics on yet another side was that, being cognition a priori, it displays a certain kinship with mathematics — a kinship that, so far as the a priori origin goes, does make the two akin; but so far as concerns the manner of cognizing from concepts in the one, set against the manner of judging simply through the construction of concepts a priori in the other, and thus the difference between a philosophical cognition and a mathematical one, there stands revealed a heterogeneity so pronounced that, though one always somehow sensed it, one could never reduce it to distinct criteria. It has thereby come to pass that, philosophers having themselves gone astray in unfolding the idea of their science, the working of it could possess no fixed aim and no reliable measuring-line, and that, saddled with so arbitrary a draft, in the dark as to the road they should take, and forever quarreling among themselves over the discoveries each insisted he had made along his own, they dragged their science first into others' contempt and in the end even into their own.
All pure cognition a priori thereby forms, in virtue of the particular cognitive faculty within which alone it can be lodged, a unity of its own, and metaphysics is that philosophy whose task is to set forth this cognition in such systematic unity. Its speculative part, which has claimed this title for itself above all — the part we call the metaphysics of nature, which weighs everything, insofar as it is (not what ought to be), out of concepts a priori — is now partitioned as follows.
Metaphysics in the narrower sense, so named, is made up of two parts: the transcendental philosophy and the physiology of pure reason. The first of these attends solely to the understanding and to reason as such within a system comprising all those concepts and principles that bear upon objects as such, positing no objects that would be given (Ontologia); the second attends to nature, that is, to the totality of given objects (be they given to the senses or, should one wish, to some other manner of intuition), and it is accordingly physiology (albeit only rationalis). Now within this rational contemplation of nature reason may be put to use in a manner either physical or hyperphysical — or, to phrase it better, either immanent or transcendent. The first bears upon nature to the extent that cognition of it admits of application within experience (in concreto); the second bears upon that linkage among the objects of experience which oversteps experience altogether. This transcendent physiology thus takes for its object either an inner linkage or an outer one, both of which, though, run past possible experience; the first is the physiology of the whole of nature, that is, transcendental cognition of the world, the second that of the whole of nature's tie with a being above nature, that is, transcendental cognition of God.
Immanent physiology, on the other hand, views nature as the totality of all objects of the senses, and hence as it is given to us, though solely under those conditions a priori on which it can be given to us at all. Its objects, however, are of just two sorts: 1. Those belonging to the outer senses, and so the totality of them, corporeal nature. 2. The object of the inner sense, the soul, and, by its basic concepts generally, thinking nature. The metaphysics of corporeal nature is termed physics — but, since it is meant to hold only the a priori principles of its cognition, rational physics. The metaphysics of thinking nature is termed psychology, and for the cause just adduced only its rational cognition is here to be understood.
The full system of metaphysics accordingly rests on four principal parts: 1. The ontology. 2. The rational physiology. 3. The rational cosmology. 4. The rational theology. The second part — namely the doctrine of nature belonging to pure reason — embraces two subdivisions, the physica rationalis75 and the psychologia rationalis.
The primordial idea of a philosophy of pure reason itself dictates this partition; the partition is therefore architectonic, answering to its essential ends, and not merely technical, arranged by kinships noticed at random and, so to say, on a gamble — and just for that reason it is also unalterable and legislative. Yet several points crop up here that stir misgiving and might sap one's conviction of its lawfulness.
In the first place, how am I to look for a cognition a priori, and so a metaphysics, of objects insofar as they are handed to our senses and thus a posteriori? and how can it be done, to cognize the nature of things by principles a priori and to reach a rational physiology ? The reply runs thus: from experience we borrow nothing beyond what is needed in order to give ourselves an object, partly of the outer, partly of the inner sense. The one comes about by the bare concept of matter (impenetrable, lifeless extension), the other by the concept of a thinking being (within the empirical inner representation: I think). For the rest, throughout the entire metaphysics of these objects we should have to hold ourselves back wholly from any empirical principle that might tack some further experience onto the concept so as to draw from it a judgment about these objects.
In the second place: what then becomes of empirical psychology, which from of old has held its ground within metaphysics, and from which, in our times, so much has been anticipated toward illuminating it, once the hope of accomplishing anything usable a priori was abandoned? My reply: it must be assigned there where the proper (empirical) doctrine of nature has its place — that is, on the flank of applied philosophy, to which pure philosophy contributes the principles a priori, so that the former must be bound up with it, yet not commingled. Empirical psychology must therefore be banished outright from metaphysics, and by the very idea of metaphysics it already stands wholly shut out. All the same, in keeping with scholastic practice one will yet still have to concede it a small corner there (albeit only by way of episode), and that on grounds of economy, since it is not yet rich enough to constitute a study on its own, and yet too weighty to be thrown out altogether or fastened somewhere else, where it would find even less affinity than in metaphysics. It is thus no more than a stranger lodged for the time being, granted a stay for a while, until in a full-scale anthropology (the counterpart to the empirical doctrine of nature) he can take up quarters of his own.
Such, then, is the general idea of metaphysics, which — because more was at first expected of it than can in fairness be demanded, and because for a while people indulged themselves with pleasant expectations — sank in the end into general disdain, once they found their hope betrayed. From the whole run of our critique one will by now be amply persuaded of this: that, granted metaphysics cannot serve as the bedrock of religion, it must nevertheless remain at all times as its rampart , and that human reason — dialectical already through the bent of its own nature — can never dispense with a science of this kind, one that curbs it and, by means of a scientific and perfectly luminous self-knowledge, holds off the ravages that an unbridled speculative reason would otherwise, quite without fail, work upon morals as well as religion. One may thus be assured — however aloof or dismissive those carry on who know how to appraise a science not by its nature but purely by its incidental effects — that we shall time and again come back to it as to a beloved from whom we have been estranged, for reason, where essential ends are here in question, is bound to labor without rest either toward searching insight or toward the wrecking of sound insights already possessed.
Metaphysics, then — of nature as much as of morals — and above all the critique of a reason that dares to fly on its own wings, which runs ahead by way of preliminary exercise (propaedeutically), is really the one thing that alone constitutes what we can, in the true sense, call philosophy. Philosophy so understood refers everything to wisdom, but by the road of science — the only road which, once it has been opened, never grows over again and suffers no wanderings astray. Mathematics, natural science, and even the empirical acquaintance with the human being carry a high worth as means — for the most part toward contingent, but in the last resort toward necessary and essential ends of mankind — yet only then through the mediation of a cognition of reason out of bare concepts, which, call it what you will, is at bottom nothing but metaphysics.
For precisely this reason metaphysics is likewise the crowning of every cultivation of human reason, indispensable even should one leave out of account its bearing as a science upon certain determinate ends. For it examines reason in respect of its elements and supreme maxims, which must themselves underlie the possibility of certain sciences and the use of them all. That, as mere speculation, it does more to fend off errors than to widen cognition detracts nothing from its worth; on the contrary, it lends it dignity and standing through the censorial office, which safeguards the general order and harmony — indeed the prosperity — of the scientific commonwealth and keeps its daring and fertile labors from drifting away from the chief end, the happiness of all.
Chapter 4. The History of Pure Reason
This title stands here merely to designate a place that is left vacant in the system and will have to be supplied at some future point. I content myself with casting, from a purely transcendental vantage point—namely the nature of pure reason—a fleeting glance over the whole of the treatments it has so far received, which to my eye admittedly presents edifices, yet only ones lying in ruins.
It is remarkable enough—though in the nature of things it could not have been otherwise—that human beings, in the childhood of philosophy, set out from precisely where we would now rather come to rest, namely by first taking up the cognition of God, together with the hope—or even the makeup—of a world beyond. Whatever crude religious concepts the ancient usages, surviving from a time even prior to the peoples' rude condition, may have brought in, this did not keep the more enlightened part from dedicating themselves to free inquiry into this object, and it was easy to see that no more solid and trustworthy way of pleasing the invisible power that rules the world—so as to be happy at least in another world—could be found than a good conduct of life. Theology and morals were on that account the two mainsprings—or better, the two points of reference—for all those abstracted inquiries of reason to which people have ever since given themselves. The former, meanwhile, was really what drew merely speculative reason, little by little, into that business which subsequently grew so famous under the title of metaphysics.
I will not now separate out the periods on which this or that transformation of metaphysics happened to fall, but only present, in a rapid outline, the difference of idea that prompted its principal revolutions. And there I find a threefold aim under which the most significant transformations were founded upon this stage of controversy.
1. As regards the object to which all our cognitions of reason refer, some were merely sensual-, others merely intellectual philosophers. Epicurus can be called the foremost philosopher of sensibility, Plato that of the intellectual realm. This distinction between the schools, however subtle it may be, dates back to the very earliest times and long persisted without a break. The adherents of the former maintained that actuality resides solely in the objects of the senses and that all the rest is fancy; the adherents of the second held, on the contrary: within the senses nothing is found but semblance, and the understanding alone cognizes what is true. On that account the former did not, for all that, deny reality to the concepts of the understanding, yet in their hands this reality was only logical, while in the hands of the others it was mystical. The former, while granting intellectual concepts, took only sensible objects to be given. The latter, by contrast, held the true objects to be merely intelligible and posited an intuition carried out through the pure understanding—one attended by no senses and, on their view, only thrown into confusion by them.
2. As concerns the origin of pure cognitions of reason—as to whether they are drawn from experience or, independently of it, find their source in reason. Aristotle can be taken as the leader of the empiricists, and Plato as that of the noologists. Locke, who in more recent days took the side of the former, and Leibniz, who took that of the latter (albeit at a sufficient distance from the latter's mystical system), have all the same proved unable to bring this quarrel to any decision. At least Epicurus, for his part, went about his sensual system far more consistently (for in his inferences he never once passed beyond the frontier of experience) than did Aristotle and Locke (but above all the latter), who, having drawn every concept and principle from experience, presses their use so far as to hold that God's existence and the immortality of the soul (although both objects lie wholly beyond the limits of possible experience) can be demonstrated every bit as evidently as some theorem of mathematics.
3. As to method. If anything at all is to bear the name of method, it must be a procedure conducted according to principles. Now the method presently dominant in this branch of investigation admits of a division into the naturalistic and the scientific. The naturalist where pure reason is concerned adopts as his principle: that on the loftiest questions making up the task of metaphysics more is to be achieved by ordinary reason without science (which he styles sound reason) than by way of speculation. He thus asserts that the size and remoteness of the moon can be settled with more assurance by the estimate of the eye than through mathematical detours. It is sheer misology raised to principles and—what is more preposterous than anything—the disregard of all artful means, trumpeted as a distinctive method for broadening one's cognition. For as far as those naturalists are concerned who act from a want of fuller insight, nothing can with good ground be charged against them. They keep to ordinary reason without parading their ignorance as a method that is supposed to hold the secret of drawing truth up from Democritus's deep well. Quod sapio, satis est mihi, non ego curo esse quod Arcesilas aerumnosique Solones (Pers.) is their watchword, under which they may, content and worthy of approval, pass their days without troubling over science or throwing its business into disarray.
As for those who observe a scientific method, they are here free to proceed either dogmatically or skeptically, though under every circumstance bound to proceed systematically. If for the first of these I here name the celebrated Wolff, and for the second David Hume, I may, consistent with my present aim, leave the others unnamed. The critical path alone still lies open. If the reader has shown the good will and patience to walk through it in my company, he may now judge whether—should he care to add his own contribution toward turning this footpath into a highroad—what many centuries were unable to accomplish might not be reached before the present one has run its course: that is, to grant human reason full contentment in the very matter that has forever engaged its craving to know, though thus far to no avail.