If we assume the being of certain things (or even only certain forms of things) to be contingent and so to be possible only through something else which is their cause, we may seek for the unconditioned ground of this causality of the supreme (and so of the conditioned) either in the physical or the teleological order (either according to the nexus effectivus or the nexus finalis). That is, we may either ask, what is the supreme productive cause of these things; or what is their supreme (absolutely unconditioned) purpose, i.e. the final purpose of that cause in its production of this or all its products generally? In the second case it is plainly presupposed that this cause is capable of representing purposes to itself, and consequently is an intelligent Being; at least it must be thought as acting in accordance with the laws of such a being.
If we follow the latter order, it is a Fundamental Proposition to which even the commonest human Reason is compelled to give immediate assent, that if there is to be in general a final purpose furnished a priori by Reason, this can be no other than man (every rational being of the world) under moral laws.133 For (and so every one judges) if the world consisted of mere lifeless, or even in part of living but irrational, beings, its existence would have no worth because in it there would be no being who would have the least concept of what worth is. Again, if there were intelligent beings, whose Reason were only able to place the worth of the existence of things in the relation of nature to themselves (their well-being), but not to furnish of itself an original worth (in freedom), then there would certainly be (relative) purposes in the world, but no (absolute) final purpose, because the existence of such rational beings would be always purposeless. But the moral laws have this peculiar characteristic that they prescribe to Reason something as a purpose without any condition, and consequently exactly as the concept of a final purpose requires. The existence of a Reason that can be for itself the supreme law in the purposive reference, in other words the existence of rational beings under moral laws, can therefore alone be thought as the final purpose of the being of a world. If on the contrary this be not so, there would be either no purpose at all in the cause of its being, or there would be purposes, but no final purpose.
The moral law as the formal rational condition of the use of our freedom obliges us by itself alone, without depending on any purpose as material condition; but it nevertheless determines for us, and indeed a priori, a final purpose towards which it obliges us to strive; and this purpose is the highest good in the world possible through freedom.
The subjective condition under which man (and, according to all our concepts, every rational finite being) can set a final purpose before himself under the above law is happiness. Consequently, the highest physical good possible in the world, to be furthered as a final purpose as far as in us lies, is happiness, under the objective condition of the harmony of man with the law of morality as worthiness to be happy.
But it is impossible for us in accordance with all our rational faculties to represent these two requirements of the final purpose proposed to us by the moral law, as connected by merely natural causes, and yet as conformable to the Idea of that final purpose. Hence the concept of the practical necessity of such a purpose through the application of our powers does not harmonise with the theoretical concept of the physical possibility of working it out, if we connect with our freedom no other causality (as a means) than that of nature.
Consequently, we must assume a moral World-Cause (an Author of the world), in order to set before ourselves a final purpose consistently with the moral law; and in so far as the latter is necessary, so far (i.e. in the same degree and on the same ground) the former also must be necessarily assumed; i.e. we must admit that there is a God.134
This proof, to which we can easily give the form of logical precision, does not say: it is as necessary to assume the Being of God as to recognise the validity of the moral law; and consequently he who cannot convince himself of the first, can judge himself free from the obligations of the second. No! there must in such case only be given up the aiming at the final purpose in the world, to be brought about by the pursuit of the second (viz. a happiness of rational beings in harmony with the pursuit of moral laws, regarded as the highest good). Every rational being would yet have to cognise himself as straitly bound by the precepts of morality, for its laws are formal and command unconditionally without respect to purposes (as the matter of volition). But the one requisite of the final purpose, as practical Reason prescribes it to beings of the world, is an irresistible purpose imposed on them by their nature (as finite beings), which Reason wishes to know as subject only to the moral law as inviolable condition, or even as universally set up in accordance with it. Thus Reason takes for final purpose the furthering of happiness in harmony with morality. To further this so far as is in our power (i.e. in respect of happiness) is commanded us by the moral law; be the issue of this endeavour what it may. The fulfilling of duty consists in the form of the earnest will, not in the intermediate causes of success.
Suppose then that partly through the weakness of all the speculative arguments so highly extolled, and partly through many irregularities in nature and the world of sense which come before him, a man is persuaded of the proposition, There is no God; he would nevertheless be contemptible in his own eyes if on that account he were to imagine the laws of duty as empty, invalid and inobligatory, and wished to resolve to transgress them boldly. Such an one, even if he could be convinced in the sequel of that which he had doubted at the first, would always be contemptible while having such a disposition, although he should fulfil his duty as regards its [external] effect as punctiliously as could be desired, for [he would be acting] from fear or from the aim at recompense, without the sentiment of reverence for duty. If, conversely, as a believer [in God] he performs his duty according to his conscience, uprightly and disinterestedly, and nevertheless believes that he is free from all moral obligation so soon as he is convinced that there is no God, this could accord but badly with an inner moral disposition.
We may then suppose the case of a righteous man [e.g. Spinoza],135 who holds himself firmly persuaded that there is no God, and also (because in respect of the Object of morality a similar consequence results) no future life; how is he to judge of his own inner purposive destination, by means of the moral law, which he reveres in practice? He desires no advantage to himself from following it, either in this or another world; he wishes, rather, disinterestedly to establish the good to which that holy law directs all his powers. But his effort is bounded; and from nature, although he may expect here and there a contingent accordance, he can never expect a regular harmony agreeing according to constant rules (such as his maxims are and must be, internally), with the purpose that he yet feels himself obliged and impelled to accomplish. Deceit, violence, and envy will always surround him, although he himself be honest, peaceable, and kindly; and the righteous men with whom he meets will, notwithstanding all their worthiness of happiness, be yet subjected by nature which regards not this, to all the evils of want, disease, and untimely death, just like the beasts of the earth. So it will be until one wide grave engulfs them together (honest or not, it makes no difference), and throws them back—who were able to believe themselves the final purpose of creation—into the abyss of the purposeless chaos of matter from which they were drawn.— The purpose, then, which this well-intentioned person had and ought to have before him in his pursuit of moral laws, he must certainly give up as impossible. Or else, if he wishes to remain dependent upon the call of his moral internal destination, and not to weaken the respect with which the moral law immediately inspires him, by assuming the nothingness of the single, ideal, final purpose adequate to its high demand (which cannot be brought about without a violation of moral sentiment), he must, as he well can—since there is at least no contradiction from a practical point of view in forming a concept of the possibility of a morally prescribed final purpose—assume the being of a moral author of the world, that is, a God.
Pure Reason, as a practical faculty, i.e. as the faculty of determining the free use of our causality by Ideas (pure rational concepts), not only comprises in the moral law a regulative principle of our actions, but supplies us at the same time with a subjective constitutive principle in the concept of an Object which Reason alone can think, and which is to be actualised by our actions in the world according to that law. The Idea of a final purpose in the employment of freedom according to moral laws has therefore subjective practical reality. We are a priori determined by Reason to promote with all our powers the summum bonum [Weltbeste] which consists in the combination of the greatest welfare of rational beings with the highest condition of the good in itself, i.e. in universal happiness conjoined with morality most accordant to law. In this final purpose the possibility of one part, happiness, is empirically conditioned, i.e. dependent on the constitution of nature (which may or may not agree with this purpose) and is in a theoretical aspect problematical; whilst the other part, morality, in respect of which we are free from the effects of nature, stands fast a priori as to its possibility, and is dogmatically certain. It is then requisite for the objective theoretical reality of the concept of the final purpose of rational beings, that we should not only have a priori presupposed a final purpose for ourselves, but also that the creation, i.e. the world itself, should have as regards its existence a final purpose, which if it could be proved a priori would add objectivity to the subjective reality of the final purpose [of rational beings]. For if the creation has on the whole a final purpose, we cannot think it otherwise than as harmonising with the moral purpose (which alone makes the concept of a purpose possible). Now we find without doubt purposes in the world, and physical Teleology exhibits them in such abundance, that if we judge in accordance with Reason, we have ground for assuming as a principle in the investigation of nature that nothing in nature is without a purpose; but the final purpose of nature we seek there in vain. This can and must therefore, as its Idea only lies in Reason, be sought as regards its objective possibility only in rational beings. And the practical Reason of these latter not only supplies this final purpose; it also determines this concept in respect of the conditions under which alone a final purpose of creation can be thought by us.
The question is now, whether the objective reality of the concept of a final purpose of creation cannot be exhibited adequately to the theoretical requirements of pure Reason—if not apodictically for the determinant Judgement yet adequately for the maxims of the theoretical reflective Judgement? This is the least one could expect from theoretical philosophy, which undertakes to combine the moral purpose with natural purposes by means of the Idea of one single purpose; but yet this little is far more than it can accomplish.
According to the principle of the theoretical reflective Judgement we should say: if we have ground for assuming for the purposive products of nature a supreme Cause of nature—whose causality in respect of the actuality of creation is of a different kind from that required for the mechanism of nature, i.e. must be thought as the causality of an Understanding—we have also sufficient ground for thinking in this original Being not merely the purposes everywhere in nature but also a final purpose. This is not indeed a final purpose by which we can explain the presence of such a Being, but one of which we may at least convince ourselves (as was the case in physical Teleology) that we can make the possibility of such a world conceivable, not merely according to purposes, but only through the fact that we ascribe to its existence a final purpose.
But a final purpose is merely a concept of our practical Reason, and can be inferred from no data of experience for the theoretical judging of nature, nor can it be applied to the cognition of nature. No use of this concept is possible except its use for practical Reason according to moral laws; and the final purpose of creation is that constitution of the world which harmonises with that which alone we can put forward definitely according to laws, viz. the final purpose of our pure practical Reason, in so far as it is to be practical.— Now we have in the moral law, which enjoins on us in a practical point of view the application of our powers to the accomplishment of this final purpose, a ground for assuming its possibility and practicability, and consequently too (because without the concurrence of nature with a condition not in our power, its accomplishment would be impossible) a nature of things harmonious with it. Hence we have a moral ground for thinking in a world also a final purpose of creation.
We have not yet advanced from moral Teleology to a Theology, i.e. to the being of a moral Author of the world, but only to a final purpose of creation which is determined in this way. But in order to account for this creation, i.e. the existence of things, in accordance with a final purpose, we must assume not only first an intelligent Being (for the possibility of things of nature which we are compelled to judge of as purposes), but also a moral Being, as author of the world, i.e. a God. This second conclusion is of such a character that we see it holds merely for the Judgement according to concepts of practical Reason, and as such for the reflective and not the determinant Judgement. It is true that in us morally practical Reason is essentially different in its principles from technically practical Reason. But we cannot assume that it must be so likewise in the supreme World-Cause, regarded as Intelligence, and that a peculiar mode of its causality is requisite for the final purpose, different from that which is requisite merely for purposes of nature. We cannot therefore assume that in our final purpose we have not merely a moral ground for admitting a final purpose of creation (as an effect), but also for admitting a moral Being as the original ground of creation. But we may well say, that, according to the constitution of our rational faculty, we cannot comprehend the possibility of such a purposiveness in respect of the moral law, and its Object, as there is in this final purpose, apart from an Author and Governor of the world, who is at the same time its moral Lawgiver.
The actuality of a highest morally-legislating Author is therefore sufficiently established merely for the practical use of our Reason, without determining anything theoretically as regards its being. For Reason requires, in respect of the possibility of its purpose, which is given to us independently by its own legislation, an Idea through which the inability to follow up this purpose, according to the mere natural concepts of the world, is removed (sufficiently for the reflective Judgement). Thus this Idea gains practical reality, although all means of creating such for it in a theoretical point of view, for the explanation of nature and determination of the supreme Cause, are entirely wanting for speculative cognition. For the theoretical reflective Judgement physical Teleology sufficiently proves from the purposes of nature an intelligent World-Cause; for the practical Judgement moral Teleology establishes it by the concept of a final purpose, which it is forced to ascribe to creation in a practical point of view. The objective reality of the Idea of God, as moral Author of the world, cannot, it is true, be established by physical purposes alone. But nevertheless, if the cognition of these purposes is combined with that of the moral purpose, they are, by virtue of the maxim of pure Reason which bids us seek unity of principles so far as is possible, of great importance for the practical reality of that Idea, by bringing in the reality which it has for the Judgement in a theoretical point of view.
To prevent a misunderstanding which may easily arise, it is in the highest degree needful to remark that, in the first place, we can think these properties of the highest Being only according to analogy. How indeed could we explore the nature of that, to which experience can show us nothing similar? Secondly, in this way we only think the supreme Being; we cannot thereby cognise Him and ascribe anything theoretically to Him. It would be needful for the determinant Judgement in the speculative aspect of our Reason, to consider what the supreme World-Cause is in Himself. But here we are only concerned with the question what concept we can form of Him, according to the constitution of our cognitive faculties; and whether we have to assume His existence in order merely to furnish practical reality to a purpose, which pure Reason without any such presupposition enjoins upon us a priori to bring about with all our powers, i.e. in order to be able to think as possible a designed effect. Although that concept may be transcendent for the speculative Reason, and the properties which we ascribe to the Being thereby thought may, objectively used, conceal an anthropomorphism in themselves; yet the design of its use is not to determine the nature of that Being which is unattainable by us, but to determine ourselves and our will accordingly. We may call a cause after the concept which we have of its effect (though only in reference to this relation), without thereby meaning to determine internally its inner constitution, by means of the properties which can be made known to us solely by similar causes and must be given in experience. For example, amongst other properties we ascribe to the soul a vis locomotiva because bodily movements actually arise whose cause lies in the representation of them; without therefore meaning to ascribe to it the only mode [of action] that we know in moving forces (viz. by attraction, pressure, impulse, and consequently motion, which always presuppose an extended being). Just so we must assume something, which contains the ground of the possibility and practical reality, i.e. the practicability, of a necessary moral final purpose; but we can think of this, in accordance with the character of the effect expected of it, as a wise Being governing the world according to moral laws, and, conformably to the constitution of our cognitive faculties, as a cause of things distinct from nature, only in order to express the relation of this Being (which transcends all our cognitive faculties) to the Objects of our practical Reason. We do not pretend thus to ascribe to it theoretically the only causality of this kind known to us, viz. an Understanding and a Will: we do not even pretend to distinguish objectively the causality thought in this Being, as regards what is for us final purpose, from the causality thought in it as regards nature (and its purposive determinations in general). We can only assume this distinction as subjectively necessary by the constitution of our cognitive faculties, and as valid for the reflective, not for the objectively determinant Judgement. But if we come to practice, then such a regulative principle (of prudence or wisdom) [commanding us] to act conformably to that as purpose, which by the constitution of our cognitive faculties can only be thought as possible in a certain way, is at the same constitutive, i.e. practically determinant. Nevertheless, as a principle for judging of the objective possibility of things, it is no way theoretically determinant (i.e. it does not say that the only kind of possibility which belongs to the Object is that which belongs to our thinking faculty), but is a mere regulative principle for the reflective Judgement.
This moral proof is not one newly discovered, although perhaps its basis is newly set forth; since it has lain in man’s rational faculty from its earliest germ, and is only continually developed with its advancing cultivation. So soon as men begin to reflect upon right and wrong—at a time when, quite indifferent as to the purposiveness of nature, they avail themselves of it without thinking anything more of it than that it is the accustomed course of nature—this judgement is inevitable, viz. that the issue cannot be the same, whether a man has behaved candidly or falsely, fairly or violently, even though up to his life’s end, as far as can be seen, he has met with no happiness for his virtues, no punishment for his vices. It is as if they perceived a voice within [saying] that the issue must be different. And so there must lie hidden in them a representation, however obscure, of something after which they feel themselves bound to strive; with which such a result would not agree,—with which, if they looked upon the course of the world as the only order of things, they could not harmonise that inner purposive determination of their minds. Now they might represent in various rude fashions the way in which such an irregularity could be adjusted (an irregularity which must be far more revolting to the human mind than the blind chance that we are sometimes willing to use as a principle for judging of nature). But they could never think any other principle of the possibility of the unification of nature with its inner ethical laws, than a supreme Cause governing the world according to moral laws; because a final purpose in them proposed as duty, and a nature without any final purpose beyond them in which that purpose might be actualised, would involve a contradiction. As to the [inner]136 constitution of that World-Cause they could contrive much nonsense. But that moral relation in the government of the world would remain always the same, which by the uncultivated Reason, considered as practical, is universally comprehensible, but with which the speculative Reason can make far from the like advance.—And in all probability attention would be directed first by this moral interest to the beauty and the purposes in nature, which would serve excellently to strengthen this Idea though they could not be the foundation of it. Still less could that moral interest be dispensed with, because it is only in reference to the final purpose that the investigation of the purposes of nature acquires that immediate interest which displays itself in such a great degree in the admiration of them without any reference to the advantage to be derived from them.
The limitation of Reason in respect of all our Ideas of the supersensible to the conditions of its practical employment has, as far as the Idea of God is concerned, undeniable uses. For it prevents Theology from rising into Theosophy (into transcendent concepts which confound Reason), or from sinking into Demonology (an anthropomorphic way of representing the highest Being). And it also prevents Religion from turning into Theurgy (a fanatical belief that we can have a feeling of other supersensible beings and can reciprocally influence them), or into Idolatry (a superstitious belief that we can please the Supreme Being by other means than by a moral sentiment).137
For if we permit the vanity or the presumption of sophistry to determine the least thing theoretically (in a way that extends our knowledge) in respect of what lies beyond the world of sense, or if we allow any pretence to be made of insight into the being and constitution of the nature of God, of His Understanding and Will, of the laws of both and of His properties which thus affect the world, I should like to know where and at what point we will bound these assumptions of Reason. For wherever such insight can be derived, there may yet more be expected (if we only strain our reflection, as we have a mind to do). Bounds must then be put to such claims according to a certain principle, and not merely because we find that all attempts of the sort have hitherto failed, for that proves nothing against the possibility of a better result. But here no principle is possible, except either to assume that in respect of the supersensible absolutely nothing can be theoretically determined (except mere negations); or else that our Reason contains in itself a yet unused mine of cognitions, reaching no one knows how far, stored up for ourselves and our posterity.—But as concerns Religion, i.e. morals in reference to God as legislator, if the theoretical cognition of Him is to come first, morals must be adjusted in accordance with Theology; and not only is an external arbitrary legislation of a Supreme Being introduced in place of an internal necessary legislation of Reason, but also whatever is defective in our insight into the nature of this Being must extend to ethical precepts, and thus make Religion immoral and perverted.
As regards the hope of a future life, if instead of the final purpose we have to accomplish in conformity with the precept of the moral law, we ask of our theoretical faculty of cognition a clue for the judgement of Reason upon our destination (which clue is only considered as necessary or worthy of acceptance in a practical reference), then in this aspect Psychology, like Theology, gives no more than a negative concept of our thinking being. That is, none of its actions or of the phenomena of the internal sense can be explained materialistically; and hence of its separate nature and of the continuance or non-continuance of its personality after death absolutely no ampliative determinant judgement is possible on speculative grounds by means of our whole theoretical cognitive faculty. Here then everything is handed over to the teleological judging of our existence in a practically necessary aspect, and to the assumption of our continuance as a condition requisite for the final purpose absolutely furnished by Reason. And so this advantage (which indeed at first glance seems to be a loss) is apparent; that, as Theology for us can never be Theosophy, or rational Psychology become Pneumatology—an ampliative science—so on the other hand this latter is assured of never falling into Materialism. Psychology, rather, is a mere anthropology of the internal sense, i.e. is the knowledge of our thinking self in life; and, as theoretical cognition, remains merely empirical. On the other hand, rational Psychology, as far as it is concerned with questions as to our eternal existence, is not a theoretical science at all, but rests on a single conclusion of moral Teleology; as also its whole use is necessary merely on account of the latter, i.e. on account of our practical destination.
The first requisite for every proof, whether it be derived from the immediate empirical presentation (as in the proof from observation of the object or from experiment) of that which is to be proved, or by Reason a priori from principles, is this. It should not persuade, but convince,138 or at least should tend to conviction. I.e. the ground of proof or the conclusion should not be merely a subjective (aesthetical) determining ground of assent (mere illusion), but objectively valid and a logical ground of cognition; for otherwise the Understanding is ensnared, but not convinced. Such an illusory proof is that which, perhaps with good intent but yet with wilful concealment of its weaknesses, is adduced in Natural Theology. In this we bring in the great number of indications of the origin of natural things according to the principle of purposes, and take advantage of the merely subjective basis of human Reason, viz. its special propensity to think only one principle instead of several, whenever this can be done without contradiction; and, when in this principle only one or more requisites for determining a concept are furnished, to add in our thought these additional [features] so as to complete the concept of the thing by arbitrarily supplementing it. For, in truth, when we meet with so many products in nature which are to us marks of an intelligent cause, why should we not think One cause rather than many; and in this One, not merely great intelligence, power, etc., but rather Omniscience, and Omnipotence—in a word, think it as a Cause that contains the sufficient ground of such properties in all possible things? Further, why should we not ascribe to this unique, all-powerful, original Being not only intelligence for natural laws and products, but also, as to a moral Cause of the world, supreme, ethical, practical Reason? For by this completion of the concept a sufficient principle is furnished both for insight into nature and for moral wisdom; and no objection grounded in any way can be made against the possibility of such an Idea. If now at the same time the moral motives of the mind are aroused, and a lively interest in the latter is added by the force of eloquence (of which they are indeed very worthy), then there arises therefrom a persuasion of the objective adequacy of the proof; and also (in most cases of its use) a wholesome illusion which quite dispenses with all examination of its logical strictness, and even on the contrary regards this with abhorrence and dislike as if an impious doubt lay at its basis.—Now against this there is indeed nothing to say, so long as we only have regard to its popular usefulness. But then the division of the proof into the two dissimilar parts involved in the argument—belonging to physical and moral Teleology respectively—cannot and must not be prevented. For the blending of these makes it impossible to discern where the proper force of the proof lies, and in what part and how it must be elaborated in order that its validity may be able to stand the strictest examination (even if we should be compelled to admit in one part the weakness of our rational insight). Thus it is the duty of the philosopher (supposing even that he counts as nothing the claims of sincerity) to expose the above illusion, however wholesome it is, which such a confusion can produce; and to distinguish what merely belongs to persuasion from that which leads to conviction (for these are determinations of assent which differ not merely in degree but in kind), in order to present plainly the state of the mind in this proof in its whole clearness, and to be able to subject it frankly to the closest examination.
But a proof which is intended to convince, can again be of two kinds; either deciding what the object is in itself, or what it is for us (for men in general) according to our necessary rational principles of judgement (proof κατ’ ἀλήθειαν or κατ’ ἄνθρωπον, the last word being taken in its universal signification of man in general). In the first case it is based on adequate principles for the determinant Judgement, in the second for the reflective Judgement. In the latter case it can never, when resting on merely theoretical principles, tend to conviction; but if a practical principle of Reason (which is therefore universally and necessarily valid) lies at its basis, it may certainly lay claim to conviction adequate in a pure practical point of view, i.e. to moral conviction. But a proof tends to conviction, though without convincing, if it is [merely]139 brought on the way thereto; i.e. if it contains in itself only objective grounds, which although not attaining to certainty are yet of such a kind that they do not serve merely for persuasion as subjective grounds of the judgement.140
All theoretical grounds of proof resolve themselves either into: (1) Proofs by logically strict Syllogisms of Reason; or where this is not the case, (2) Conclusions according to analogy; or where this also has no place, (3) Probable opinion; or finally, which has the least weight, (4) Assumption of a merely possible ground of explanation, i.e. Hypothesis.—Now I say that all grounds of proof in general, which aim at theoretical conviction, can bring about no belief of this kind from the highest to the lowest degree, if there is to be proved the proposition of the existence of an original Being, as a God, in the signification adequate to the whole content of this concept; viz. a moral Author of the world, by whom the final purpose of creation is at the same time supplied.
(1.) As to the logically accurate proof proceeding from universal to particular, we have sufficiently established in the Critique the following: Since no intuition possible for us corresponds to the concept of a Being that is to be sought beyond nature—whose concept therefore, so far as it is to be theoretically determined by synthetical predicates, remains always problematical for us—there is absolutely no cognition of it to be had (by which the extent of our theoretical knowledge is in the least enlarged). The particular concept of a supersensible Being cannot be subsumed under the universal principles of the nature of things, in order to conclude from them to it, because those principles are valid simply for nature, as an object of sense.
(2.) We can indeed think one of two dissimilar things, even in the very point of their dissimilarity, in accordance with the analogy141 of the other; but we cannot, from that wherein they are dissimilar, conclude from the one to the other by analogy, i.e. transfer from the one to the other this sign of specific distinction. Thus I can, according to the analogy of the law of the equality of action and reaction in the mutual attraction and repulsion of bodies, also conceive of the association of the members of a commonwealth according to rules of right; but I cannot transfer to it those specific determinations (material attraction or repulsion), and ascribe them to the citizens in order to constitute a system called a state.—Just so we can indeed conceive of the causality of the original Being in respect of the things of the world, as natural purposes, according to the analogy of an Understanding, as ground of the forms of certain products which we call works of art (for this only takes place on behalf of the theoretical or practical use that we have to make by our cognitive faculty of this concept in respect of the natural things in the world according to a certain principle). But we can in no way conclude according to analogy, because in the case of beings of the world Understanding must be ascribed to the cause of an effect which is judged artificial, that in respect of nature the same causality which we perceive in men attaches also to the Being which is quite distinct from nature. For this concerns the very point of dissimilarity which is thought between a cause sensibly conditioned in respect of its effects and the supersensible original Being itself in our concept of it, and which therefore cannot be transferred from one to the other.— In the very fact that I must conceive the divine causality only according to the analogy of an Understanding (which faculty we know in no other being than in sensibly-conditioned man) lies the prohibition to ascribe to it this Understanding in its peculiar signification.142
(3.) Opinion finds in a priori judgements no place whatever, for by them we either cognise something as quite certain or else cognise nothing at all. But if the given grounds of proof from which we start (as here from the purposes in the world) are empirical, then we cannot even with their aid form any opinion as to anything beyond the world of sense, nor can we concede to such venturesome judgements the smallest claim to probability. For probability is part of a certainty possible in a certain series of grounds (its grounds compare with the sufficient ground as parts with a whole), the insufficient ground of which must be susceptible of completion. But since, as determining grounds of one and the same judgement, they must be of the same kind, for otherwise they would not together constitute a whole (such as certainty is), one part of them cannot lie within the bounds of possible experience and another outside all possible experience. Consequently, since merely empirical grounds of proof lead to nothing supersensible, and since what is lacking in the series of them cannot in any way be completed, we do not approach in the least nearer in our attempt to attain by their means to the supersensible and to a cognition thereof. Thus in any judgement about the latter by means of arguments derived from experience, probability has no place.
(4.) If an hypothesis is to serve for the explanation of the possibility of a given phenomenon, at least its possibility must be completely certain.143 It is sufficient that in an hypothesis I disclaim any cognition of actuality (which is claimed in an opinion given out as probable); more than this I cannot give up. The possibility of that which I place at the basis of my explanation, must at least be exposed to no doubt; otherwise there would be no end of empty chimeras. But to assume the possibility of a supersensible Being determined according to certain concepts would be a completely groundless supposition. For here none of the conditions requisite for cognition, as regards that in it which rests upon intuition, is given, and so the sole criterion of possibility remaining is the mere principle of Contradiction (which can only prove the possibility of the thought, not of the object thought).
The result then is this. For the existence [Dasein] of the original Being, as a Godhead, or of the soul as an immortal spirit, absolutely no proof in a theoretical point of view is possible for the human Reason, which can bring about even the least degree of belief. The ground of this is quite easy to comprehend. For determining our Ideas of the supersensible we have no material whatever, and we must derive this latter from things in the world of sense, which is absolutely inadequate for such an Object. Thus, in the absence of all determination of it, nothing remains but the concept of a non-sensible something which contains the ultimate ground of the world of sense, but which does not furnish any knowledge (any amplification of the concept) of its inner constitution.
If we look merely to the way in which anything can be for us (according to the subjective constitution of our representative powers) an Object of knowledge (res cognoscibilis), then our concepts will not cohere with Objects, but merely with our cognitive faculties and the use which they can make of a given representation (in a theoretical or practical point of view). Thus the question whether anything is or is not a cognisable being is not a question concerning the possibility of things but of our knowledge of them.
Cognisable things are of three kinds: things of opinion (opinabile); things of fact (scibile); and things of faith (mere credibile).
(1.) Objects of mere rational Ideas, which for theoretical knowledge cannot be presented in any possible experience, are so far not cognisable things, and consequently in respect of them we can form no opinion; for to form an opinion a priori is absurd in itself and the straight road to mere chimeras. Either then our proposition is certain a priori or it contains nothing for belief. Therefore things of opinion are always Objects of an empirical cognition at least possible in itself (objects of the world of sense); but, which, on account merely of the [low] degree of this faculty that we possess, is for us impossible. Thus the ether of the new physicists,144 an elastic fluid pervading all other matter (mingled intimately with it) is a mere thing of opinion, yet is such that, if our external senses were sharpened to the highest degree, it could be perceived; though it can never be presented in any observation or experiment. To assume [the existence of] rational inhabitants of other planets is a thing of opinion; for if we could come closer to them, which is in itself possible, we should decide by experience whether they did or did not exist; but as we shall never come so near, it remains in the region of opinion. But to hold the opinion that there are in the material universe pure thinking spirits without bodies (viz. if we dismiss as unworthy of our notice certain phenomena which have been published as actual145) is to be called poetic fiction. This is no thing of opinion, but a mere Idea which remains over, when we remove from a thinking being everything material, and only leave thought to it. Whether then the latter (which we know only in man, that is, in combination with a body) does survive, we cannot decide. Such a thing is a sophistical being (ens rationis ratiocinantis), not a rational being (ens rationis ratiocinatae)146; of which latter it is possible to show conclusively, the objective reality of its concept; at least for the practical use of Reason, because this which has its peculiar and apodictically certain principles a priori, demands (postulates) it.
(2.) Objects for concepts, whose objective reality can be proved (whether through pure Reason or through experience, and, in the first case, from its theoretical or practical data, in all cases by means of a corresponding intuition) are things of fact (res facti).147 Of this kind are the mathematical properties of magnitudes (in geometry), because they are susceptible of a presentation a priori for the theoretical use of Reason. Further, things or their characteristics, which can be exhibited in experience (either our own or that of others through the medium of testimony) are likewise things of fact.—And, what is very remarkable, there is one rational Idea (susceptible in itself of no presentation in intuition, and consequently, of no theoretical proof of its possibility) which also comes under things of fact. This is the Idea of freedom, whose reality, regarded as that of a particular kind of causality (of which the concept, theoretically considered, would be transcendent), may be exhibited by means of practical laws of pure Reason, and conformably to this, in actual actions, and, consequently, in experience.—This is the only one of all the Ideas of pure Reason, whose object is a thing of fact, and to be reckoned under the scibilia.
(3.) Objects, which in reference to the use of pure practical Reason that is in conformity with duty must be thought a priori (whether as consequences or as grounds), but which are transcendent for its theoretical use, are mere things of faith. Of this kind is the highest good in the world, to be brought about by freedom.148 The concept of this cannot be established as regards its objective reality in any experience possible for us and thus adequately for the theoretical use of Reason; but its use is commanded by practical pure Reason [in reference to the best possible working out of that purpose],149 and it consequently must be assumed possible. This commanded effect, together with the only conditions of its possibility thinkable by us, viz. the Being of God and the immortality of the soul, are things of faith (res fidei), and of all objects are the only ones which can be so called.150 For though what we learn by testimony from the experience of others must be believed by us, yet it is not therefore a thing of faith; for it was the proper experience of some one witness and so a thing of fact, or is presupposed as such. Again it must be possible by this path (that of historical faith) to arrive at knowledge; and the Objects of history and geography, like everything in general which it is at least possible to know by the constitution of our cognitive faculties, belong not to things of faith but to things of fact. It is only objects of pure Reason which can be things of faith at all, though not as objects of the mere pure speculative Reason: for then they could not be reckoned with certainty among things, i.e. Objects of that cognition which is possible for us. They are Ideas, i.e. concepts of the objective reality of which we cannot theoretically be certain. On the other hand, the highest final purpose to be worked out by us, by which alone we can become worthy of being ourselves the final purpose of creation, is an Idea which has in a practical reference objective reality for us, and is also a thing. But because we cannot furnish such reality to this concept in a theoretical point of view, it is a mere thing of faith of the pure Reason, along with God and Immortality, as the conditions under which alone we, in accordance with the constitution of our (human) Reason, can conceive the possibility of that effect of the use of our freedom in conformity with law. But belief in things of faith is a belief in a pure practical point of view, i.e. a moral faith, which proves nothing for theoretical pure rational cognition, but only for that which is practical and directed to the fulfilment of its duties; it in no way extends speculation or the practical rules of prudence in accordance with the principle of self-love. If the supreme principle of all moral laws is a postulate, so is also the possibility of its highest Object; and consequently, too, the condition under which we can think this possibility is postulated along with it and by it. Thus the cognition of the latter is neither knowledge nor opinion of the being and character of these conditions, regarded as theoretical cognition; but is a mere assumption in a reference which is practical and commanded for the moral use of our Reason.
If we were able also plausibly to base upon the purposes of nature, which physical Teleology presents to us in such rich abundance, a determinate concept of an intelligent World-Cause, then the existence [Dasein] of this Being would not be a thing of faith. For since this would not be assumed on behalf of the performance of my duty, but only in reference to the explanation of nature, it would be merely the opinion and hypothesis most conformable to our Reason. Now such Teleology leads in no way to a determinate concept of God; on the contrary, this can only be found in the concept of a moral Author of the World, because this alone furnishes the final purpose to which we can only reckon ourselves [as attached] if we behave conformably to what the moral law prescribes as final purpose and consequently obliges us [to do]. Hence it is only by its reference to the Object of our duty, as the condition of the possibility of attaining the final purpose of the same, that the concept of God attains the privilege of counting as a thing of faith, in our belief; but on the other hand, this same concept cannot make its Object valid as a thing of fact. For, although the necessity of duty is very plain for practical Reason, yet the attainment of its final purpose, so far as it is not altogether in our own power, is only assumed on behalf of the practical use of Reason, and therefore is not so practically necessary as duty itself.151
Faith (as habitus, not as actus) is the moral attitude of Reason as to belief in that which is unattainable by theoretical cognition. It is therefore the constant principle of the mind, to assume as true, on account of the obligation in reference to it, that which it is necessary to presuppose as condition of the possibility of the highest moral final purpose152; although its possibility or impossibility be alike impossible for us to see into. Faith (absolutely so called) is trust in the attainment of a design, the promotion of which is a duty, but the possibility of the fulfilment of which (and consequently also that of the only conditions of it thinkable by us) is not to be comprehended by us. Faith, then, that refers to particular objects, which are not objects of possible knowledge or opinion (in which latter case it ought to be called, especially in historical matters, credulity and not faith), is quite moral. It is a free belief, not in that for which dogmatical proofs for the theoretically determinant Judgement are to be found, or in that to which we hold ourselves bound, but in that which we assume on behalf of a design in accordance with laws of freedom. This, however, is not, like opinion, without any adequate ground; but, is grounded as in Reason (although only in respect of its practical employment), and adequately for its design. For without this, the moral attitude of thought in its repudiation of the claim of the theoretical Reason for proofs (of the possibility of the Objects of morality) has no permanence; but wavers between practical commands and theoretical doubts. To be incredulous means to cling to maxims, and not to believe testimony in general; but he is unbelieving, who denies all validity to rational Ideas, because there is wanting a theoretical ground of their reality.154 He judges therefore dogmatically. A dogmatical unbelief cannot subsist together with a moral maxim dominant in the mental attitude (for Reason cannot command one to follow a purpose, which is cognised as nothing more than a chimera); but a doubtful faith can. To this the absence of conviction by grounds of speculative Reason is only a hindrance, the influence of which upon conduct a critical insight into the limits of this faculty can remove, while it substitutes by way of compensation a paramount practical belief.