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BOOK II.: DIALECTIC OF PURE PRACTICAL REASON. - Immanuel Kant, Kant’s Critique of Practical Reason and Other Works on the Theory of Ethics 
Kant’s Critique of Practical Reason and Other Works on the Theory of Ethics, trans. Thomas Kingsmill Abbott, B.D., Fellow and Tutor of Trinity College, Dublin, 4th revised ed. (London: Kongmans, Green and Co., 1889).
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DIALECTIC OF PURE PRACTICAL REASON.
of a dialectic of pure practical reason generally.
PURE reason always has its dialectic, whether it is considered in its speculative or its practical employment; for it requires the absolute totality of the conditions of what is given conditioned, and this can only be found in things in themselves. But as all conceptions of things in themselves must be referred to intuitions, and with us men these can never be other than sensible, and hence can never enable us to know objects as things in themselves but only as appearances, and since the unconditioned can never be found in this chain of appearances which consists only of conditioned and conditions; thus from applying this rational idea of the totality of the conditions (in other words of the unconditioned) to appearances there arises an inevitable illusion, as if these latter were things in themselves (242) (for in the absence of a warning critique they are always regarded as such). This illusion would never be noticed as delusive if it did not betray itself by a conflict of reason with itself, when it applies to appearances its fundamental principle of presupposing the unconditioned to everything conditioned. By this, however, reason is compelled to trace this illusion to its source, and search how it can be removed, and this can only be done by a complete critical examination of the whole pure faculty of reason; so that the antinomy of the pure reason which is manifest in its dialectic is in fact the most beneficial error into which human reason could never have fallen, since it at last drives us to search for the key to escape from this labyrinth; and when this key is found, it further discovers that which we did not seek but yet had need of, namely, a view into a higher and an immutable order of things, in which we even now are, and in which we are thereby enabled by definite precepts to continue to live according to the highest dictates of reason.
It may be seen in detail in the Critique of Pure Reason how in its speculative employment this natural dialectic is to be solved, and how the error which arises from a very natural illusion may be guarded against. But reason in its practical use is not a whit better off. As pure practical reason, it likewise seeks to find the unconditioned for the practically conditioned (which rests on inclinations and natural wants), and this not as the determining principle of the will, but even when this is given (in the moral law) it seeks the unconditioned totality of the object of pure practical reason under the name of the Summum Bonum.
To define this idea practically, i. e. sufficiently for the maxims of our rational conduct (243), is the business of practical wisdom [Weisheitslehre], and this again as a science is philosophy, in the sense in which the word was understood by the ancients, with whom it meant instruction in the conception in which the summum bonum was to be placed, and the conduct by which it was to be obtained. It would be well to leave this word in its ancient signification as a doctrine of the summum bonum, so far as reason endeavours to make this into a science. For on the one hand the restriction annexed would suit the Greek expression (which signifies the love of wisdom), and yet at the same time would be sufficient to embrace under the name of philosophy the love of science: that is to say, of all speculative rational knowledge, so far as it is serviceable to reason, both for that conception and also for the practical principle determining our conduct, without letting out of sight the main end, on account of which alone it can be called a doctrine of practical wisdom. On the other hand, it would be no harm to deter the self-conceit of one who ventures to claim the title of philosopher by holding before him in the very definition a standard of self-estimation which would very much lower his pretensions. For a teacher of wisdom would mean something more than a scholar who has not come so far as to guide himself, much less to guide others, with certain expectation of attaining so high an end: it would mean a master in the knowledge of wisdom, which implies more than a modest man would claim for himself. Thus philosophy as well as wisdom would always remain an ideal, which objectively is presented complete in reason alone, while subjectively for the person it is only the goal of his unceasing endeavours, and no one would be justified in professing to be in possession of it so as to assume the name of philosopher, who could not also show its infallible effects in his own person as an example (244) (in his self-mastery and the unquestioned interest that he takes pre-eminently in the general good), and this the ancients also required as a condition of deserving that honourable title.
We have another preliminary remark to make respecting the dialectic of the pure practical reason, on the point of the definition of the summum bonum (a successful solution of which dialectic would lead us to expect, as in case of that of the theoretical reason, the most beneficial effects, inasmuch as the self-contradictions of pure practical reason honestly stated, and not concealed, force us to undertake a complete critique of this faculty).
The moral law is the sole determining principle of a pure will. But since this is merely formal (viz. as prescribing only the form of the maxim as universally legislative), it abstracts as a determining principle from all matter—that is to say, from every object of volition. Hence, though the summum bonum may be the whole object of a pure practical reason, i. e. a pure will, yet it is not on that account to be regarded as its determining principle; and the moral law alone must be regarded as the principle on which that and its realization or promotion are aimed at. This remark is important in so delicate a case as the determination of moral principles, where the slightest misinterpretation perverts men’s minds. For it will have been seen from the Analytic, that if we assume any object under the name of a good as a determining principle of the will prior to the moral law, and then deduce from it the supreme practical principle, this would always introduce heteronomy, and crush out the moral principle.
It is, however, evident that if the notion of the summum bonum includes that of the moral law (245) as its supreme condition, then the summum bonum would not merely be an object, but the notion of it and the conception of its existence as possible by our own practical reason would likewise be the determining principle of the will, since in that case the will is in fact determined by the moral law which is already included in this conception, and by no other object, as the principle of autonomy requires. This order of the conceptions of determination of the will must not be lost sight of, as otherwise we should misunderstand ourselves, and think we had fallen into a contradiction, while everything remains in perfect harmony.
of the dialectic of pure reason in defining the conception of the “summum bonum.”
The conception of the summum itself contains an ambiguity which might occasion needless disputes if we did not attend to it. The summum may mean either the supreme (supremum) or the perfect (consummatum). The former is that condition which is itself unconditioned, i. e. is not subordinate to any other (originarium); the second is that whole which is not a part of a greater whole of the same kind (perfectissimum). It has been shown in the Analytic that virtue (as worthiness to be happy) is the supreme condition of all that can appear to us desirable, and consequently of all our pursuit of happiness, and is therefore the supreme good. But it does not follow that it is the whole and perfect good as the object of the desires of rational finite beings; for this requires happiness also, and that not merely in the partial eyes of the person who makes himself an end, but even in the judgment of an impartial reason, which regards persons in general as ends in themselves. For to need happiness, to deserve it (247), and yet at the same time not to participate in it, cannot be consistent with the perfect volition of a rational being possessed at the same time of all power, if, for the sake of experiment, we conceive such a being. Now inasmuch as virtue and happiness together constitute the possession of the summum bonum in a person, and the distribution of happiness in exact proportion to morality (which is the worth of the person, and his worthiness to be happy) constitutes the summum bonum of a possible world; hence this summum bonum expresses the whole, the perfect good, in which, however, virtue as the condition is always the supreme good, since it has no condition above it; whereas happiness, while it is pleasant to the possessor of it, is not of itself absolutely and in all respects good, but always presupposes morally right behaviour as its condition.
When two elements are necessarily united in one concept they must be connected as reason and consequence, and this either so that their unity is considered as analytical (logical connexion), or as synthetical (real connexion)—the former following the law of identity, the latter that of causality. The connexion of virtue and happiness may therefore be understood in two ways: either the endeavour to be virtuous and the rational pursuit of happiness are not two distinct actions, but absolutely identical, in which case no maxim need be made the principle of the former, other than what serves for the latter; or the connexion consists in this, that virtue produces happiness as something distinct from the consciousness of virtue, as a cause produces an effect.
The ancient Greek schools were, properly speaking, only two, and in determining the conception of the summum bonum these followed in fact one and the same method, inasmuch as they did not allow virtue and happiness to be regarded as two distinct elements of the summum bonum, and consequently sought (248) the unity of the principle by the rule of identity; but they differed as to which of the two was to be taken as the fundamental notion. The Epicurean said: To be conscious that one’s maxims lead to happiness is virtue; the Stoic said: To be conscious of one’s virtue is happiness. With the former, Prudence was equivalent to morality; with the latter, who chose a higher designation for virtue, morality alone was true wisdom.
While we must admire the men who in such early times tried all imaginable ways of extending the domain of philosophy, we must at the same time lament that their acuteness was unfortunately misapplied in trying to trace out identity between two extremely heterogeneous notions, those of happiness and virtue. But it agreed with the dialectical spirit of their times (and subtle minds are even now sometimes misled in the same way) to get rid of irreconcilable differences in principle by seeking to change them into a mere contest about words, and thus apparently working out the identity of the notion under different names, and this usually occurs in cases where the combination of heterogeneous principles lies so deep or so high, or would require so complete a transformation of the doctrines assumed in the rest of the philosophical system, that men are afraid to penetrate deeply into the real difference, and prefer treating it as a difference in matters of form.
While both schools sought to trace out the identity of the practical principles of virtue and happiness, they were not agreed as to the way in which they tried to force this identity, but were separated infinitely from one another, the one placing its principle on the side of sense, the other on that of reason; the one in the consciousness of sensible wants, the other in the independence of practical reason (249) on all sensible grounds of determination. According to the Epicurean the notion of virtue was already involved in the maxim: To promote one’s own happiness; according to the Stoics, on the other hand, the feeling of happiness was already contained in the consciousness of virtue. Now whatever is contained in another notion is identical with part of the containing notion, but not with the whole, and moreover two wholes may be specifically distinct, although they consist of the same parts, namely, if the parts are united into a whole in totally different ways. The Stoic maintained that virtue was the whole summum bonum, and happiness only the consciousness of possessing it, as making part of the state of the subject. The Epicurean maintained that happiness was the whole summum bonum, and virtue only the form of the maxim for its pursuit, viz. the rational use of the means for attaining it.
Now it is clear from the Analytic that the maxims of virtue and those of private happiness are quite heterogeneous as to their supreme practical principle; and although they belong to one summum bonum which together they make possible, yet they are so far from coinciding that they restrict and check one another very much in the same subject. Thus the question, How is the summum bonum practically possible? still remains an unsolved problem, notwithstanding all the attempts at coalition that have hitherto been made. The Analytic has, however, shown what it is that makes the problem difficult to solve; namely, that happiness and morality are two specifically distinct elements of the summum bonum, and therefore their combination cannot be analytically cognised (as if the man that seeks his own happiness should find by mere analysis of his conception that in so acting he is virtuous, or as if the man that follows virtue should in the consciousness of such conduct find that he is already happy ipso facto) (250), but must be a synthesis of concepts. Now since this combination is recognised as à priori, and therefore as practically necessary, and consequently not as derived from experience, so that the possibility of the summum bonum does not rest on any empirical principle, it follows that the deduction [legitimation] of this concept must be transcendental. It is à priori (morally) necessary to produce the summum bonum by freedom of will: therefore the condition of its possibility must rest solely on à priori principles of cognition.
—The Antinomy of Practical Reason.
In the summum bonum which is practical for us, i. e. to be realised by our will, virtue and happiness are thought as necessarily combined, so that the one cannot be assumed by pure practical reason without the other also being attached to it. Now this combination (like every other) is either analytical or synthetical. It has been shown that it cannot be analytical; it must then be synthetical, and, more particularly, must be conceived as the connexion of cause and effect, since it concerns a practical good, i. e. one that is possible by means of action; consequently either the desire of happiness must be the motive to maxims of virtue, or the maxim of virtue must be the efficient cause of happiness. The first is absolutely impossible, because (as was proved in the Analytic) maxims which place the determining principle (251) of the will in the desire of personal happiness are not moral at all, and no virtue can be founded on them. But the second is also impossible, because the practical connexion of causes and effects in the world, as the result of the determination of the will, does not depend upon the moral dispositions of the will, but on the knowledge of the laws of nature and the physical power to use them for one’s purposes; consequently we cannot expect in the world by the most punctilious observance of the moral laws any necessary connexion of happiness with virtue adequate to the summum bonum. Now as the promotion of this summum bonum, the conception of which contains this connexion, is à priori a necessary object of our will, and inseparably attached to the moral law, the impossibility of the former must prove the falsity of the latter. If then the supreme good is not possible by practical rules, then the moral law also which commands us to promote it is directed to vain imaginary ends, and must consequently be false.
—Critical Solution of the Antinomy of Practical Reason.
The antinomy of pure speculative reason exhibits a similar conflict between freedom and physical necessity in the causality of events in the world. It was solved by showing that there is no real contradiction when the events and even the world in which they occur are regarded (as they ought to be) merely as appearances; since one and the same acting being, as an appearance (even to his own inner sense) (252) has a causality in the world of sense that always conforms to the mechanism of nature, but with respect to the same events, so far as the acting person regards himself at the same time as a noumenon (as pure intelligence in an existence not dependent on the condition of time), he can contain a principle by which that causality acting according to laws of nature is determined, but which is itself free from all laws of nature.
It is just the same with the foregoing antinomy of pure practical reason. The first of the two propositions—That the endeavour after happiness produces a virtuous mind, is absolutely false; but the second, That a virtuous mind necessarily produces happiness, is not absolutely false, but only in so far as virtue is considered as a form of causality in the sensible world, and consequently only if I suppose existence in it to be the only sort of existence of a rational being; it is then only conditionally false. But as I am not only justified in thinking that I exist also as a noumenon in a world of the understanding, but even have in the moral law a purely intellectual determining principle of my causality (in the sensible world), it is not impossible that morality of mind should have a connexion as cause with happiness (as an effect in the sensible world) if not immediate yet mediate (viz.: through an intelligent author of nature), and moreover necessary; while in a system of nature which is merely an object of the senses this combination could never occur except contingently, and therefore could not suffice for the summum bonum.
Thus, notwithstanding this seeming conflict of practical reason with itself, the summum bonum, which is the necessary supreme end of a will morally determined, is a true object thereof; for it is practically possible, and the maxims of the will which as regards their matter refer to it, have objective reality, which at first was threatened by the antinomy that appeared in the connexion (253) of morality with happiness by a general law; but this was merely from a misconception, because the relation between appearances was taken for a relation of the things in themselves to these appearances.
When we find ourselves obliged to go so far, namely, to the connexion with an intelligible world, to find the possibility of the summum bonum, which reason points out to all rational beings as the goal of all their moral wishes, it must seem strange that, nevertheless, the philosophers both of ancient and modern times have been able to find happiness in accurate proportion to virtue even in this life (in the sensible world), or have persuaded themselves that they were conscious thereof. For Epicurus as well as the Stoics extolled above everything the happiness that springs from the consciousness of living virtuously; and the former was not so base in his practical precepts as one might infer from the principles of his theory, which he used for explanation and not for action, or as they were interpreted by many who were misled by his using the term pleasure for contentment; on the contrary, he reckoned the most disinterested practice of good amongst the ways of enjoying the most intimate delight, and his scheme of pleasure (by which he meant constant cheerfulness of mind) included the moderation and control of the inclinations, such as the strictest moral philosopher might require. He differed from the Stoics chiefly in making this pleasure the motive, which they very rightly refused to do. For, on the one hand, the virtuous Epicurus, like many well-intentioned men of this day, who do not reflect deeply enough on their principles, fell into the error of pre-supposing the virtuous disposition in the persons for whom he wished to provide the springs to virtue (and indeed the upright man cannot be happy (254) if he is not first conscious of his uprightness; since with such a character the reproach that his habit of thought would oblige him to make against himself in case of transgression, and his moral self-condemnation would rob him of all enjoyment of the pleasantness which his condition might otherwise contain). But the question is, How is such a disposition possible in the first instance, and such a habit of thought in estimating the worth of one’s existence, since prior to it there can be in the subject no feeling at all for moral worth? If a man is virtuous without being conscious of his integrity in every action, he will certainly not enjoy life, however favourable fortune may be to him in its physical circumstances; but can we make him virtuous in the first instance, in other words, before he esteems the moral worth of his existence so highly, by praising to him the peace of mind that would result from the consciousness of an integrity for which he has no sense?
On the other hand, however, there is here an occasion of a vitium subreptionis, and as it were of an optical illusion, in the self-consciousness of what one does as distinguished from what one feels, an illusion which even the most experienced cannot altogether avoid. The moral disposition of mind is necessarily combined with a consciousness that the will is determined directly by the law. Now the consciousness of a determination of the faculty of desire is always the source of a satisfaction in the resulting action; but this pleasure, this satisfaction in oneself, is not the determining principle of the action; on the contrary, the determination of the will directly by reason is the source of the feeling of pleasure, and this remains a pure practical not sensible determination of the faculty of desire. Now as this determination has exactly the same effect within (255) in impelling to activity, that a feeling of the pleasure to be expected from the desired action would have had, we easily look on what we ourselves do as something which we merely passively feel, and take the moral spring for a sensible impulse, just as it happens in the so-called illusion of the senses (in this case the inner sense). It is a sublime thing in human nature to be determined to actions immediately by a purely rational law; sublime even is the illusion that regards the subjective side of this capacity of intellectual determination as something sensible, and the effect of a special sensible feeling (for an intellectual feeling would be a contradiction). It is also of great importance to attend to this property of our personality, and as much as possible to cultivate the effect of reason on this feeling. But we must beware lest by falsely extolling this moral determining principle as a spring, making its source lie in particular feelings of pleasure (which are in fact only results), we degrade and disfigure the true genuine spring, the law itself, by putting as it were a false foil upon it. Respect, not pleasure or enjoyment of happiness, is something for which it is not possible that reason should have any antecedent feeling as its foundation (for this would always be sensible and pathological); [and] 1 consciousness of immediate obligation of the will by the law is by no means analogous to the feeling of pleasure, although in relation to the faculty of desire it produces the same effect, but from different sources: it is only by this mode of conception, however, that we can attain what we are seeking, namely, that actions be done not merely in accordance with duty (as a result of pleasant feelings), but from duty, which must be the true end of all moral cultivation.
Have we not, however, a word which does not express enjoyment, as happiness does (256), but indicates a satisfaction in one’s existence, an analogue of the happiness which must necessarily accompany the consciousness of virtue? Yes! this word is self-contentment, which in its proper signification always designates only a negative satisfaction in one’s existence, in which one is conscious of needing nothing. Freedom and the consciousness of it as a faculty of following the moral law with unyielding resolution is independence on inclinations, at least as motives determining (though not as affecting) our desire, and so far as I am conscious of this freedom in following my moral maxims, it is the only source of an unaltered contentment which is necessarily connected with it and rests on no special feeling. This may be called intellectual contentment. The sensible contentment (improperly so-called) which rests on the satisfaction of the inclinations, however delicate they may be imagined to be, can never be adequate to the conception of it. For the inclinations change, they grow with the indulgence shown them, and always leave behind a still greater void than we had thought to fill. Hence they are always burdensome to a rational being, and although he cannot lay them aside, they wrest from him the wish to be rid of them. Even an inclination to what is right (e. g. to beneficence), though it may much facilitate the efficacy of the moral maxims, cannot produce any. For in these all must be directed to the conception of the law as a determining principle, if the action is to contain morality and not merely legality. Inclination is blind and slavish whether it be of a good sort or not, and when morality is in question, reason must not play the part merely of guardian to inclination, but, disregarding it altogether, must attend simply to its own interest as pure practical reason (257). This very feeling of compassion and tender sympathy, if it precedes the deliberation on the question of duty and becomes a determining principle, is even annoying to right-thinking persons, brings their deliberate maxims into confusion, and makes them wish to be delivered from it and to be subject to law-giving reason alone.
From this we can understand how the consciousness of this faculty of a pure practical reason produces by action (virtue) a consciousness of mastery over one’s inclinations, and therefore of independence on them, and consequently also on the discontent that always accompanies them, and thus a negative satisfaction with one’s state, i. e. contentment, which is primarily contentment with one’s own person. Freedom itself becomes in this way (namely indirectly) capable of an enjoyment which cannot be called happiness, because it does not depend on the positive concurrence of a feeling, nor is it, strictly speaking, bliss, since it does not include complete independence on inclinations and wants, but it resembles bliss in so far as the determination of one’s will at least can hold itself free from their influence; and thus, at least in its origin, this enjoyment is analogous to the self-sufficiency which we can ascribe only to the Supreme Being.
From this solution of the antinomy of pure practical reason it follows that in practical principles we may at least conceive as possible a natural and necessary connexion between the consciousness of morality and the expectation of a proportionate happiness as its result, though it does not follow that we can know or perceive this connexion; that, on the other hand, principles of the pursuit of happiness cannot possibly produce morality; that, therefore, morality is the supreme good (as the first condition of the summum bonum), while happiness constitutes its second element, but only in such a way that it is the morally conditioned, but necessary consequence of the former (258). Only with this subordination is the summum bonum the whole object of pure practical reason, which must necessarily conceive it as possible, since it commands us to contribute to the utmost of our power to its realization. But since the possibility of such connexion of the conditioned with its condition belongs wholly to the supersensual relation of things, and cannot be given according to the laws of the world of sense, although the practical consequences of the idea belong to the world of sense, namely, the actions that aim at realizing the summum bonum; we will therefore endeavour to set forth the grounds of that possibility, first in respect of what is immediately in our power, and then secondly in that which is not in our power, but which reason presents to us as the supplement of our impotence, for the realization of the summum bonum (which by practical principles is necessary).
—Of the Primacy of Pure Practical Reason in its Union with the Speculative Reason.
By primacy between two or more things connected by reason, I understand the prerogative belonging to one, of being the first determining principle in the connexion with all the rest. In a narrower practical sense it means the prerogative of the interest of one in so far as the interest of the other is subordinated to it, while it is not postponed to any other. To every faculty of the mind we can attribute an interest, that is a principle that contains the condition on which alone the former is called into exercise. Reason, as the faculty of principles, determines (260) the interest of all the powers of the mind, and is determined by its own. The interest of its speculative employment consists in the cognition of the object pushed to the highest à priori principles: that of its practical employment, in the determination of the will in respect of the final and complete end. As to what is necessary for the possibility of any employment of reason at all, namely, that its principles and affirmations should not contradict one another, this constitutes no part of its interest, but is the condition of having reason at all; it is only its development, not mere consistency with itself, that is reckoned as its interest.
If practical reason could not assume or think as given, anything further than what speculative reason of itself could offer it from its own insight, the latter would have the primacy. But supposing that it had of itself original à priori principles with which certain theoretical positions were inseparably connected, while these were withdrawn from any possible insight of speculative reason (which, however, they must not contradict); then the question is, which interest is the superior (not which must give way, for they are not necessarily conflicting), whether speculative reason, which knows nothing of all that the practical offers for its acceptance, should take up these propositions, and (although they transcend it) try to unite them with its own concepts as a foreign possession handed over to it, or whether it is justified in obstinately following its own separate interest, and according to the canonic of Epicurus rejecting as vain subtlety everything that cannot accredit its objective reality by manifest examples to be shown in experience, even though it should be never so much interwoven with the interest of the practical (pure) use of reason, and in itself not contradictory to the theoretical, merely because it infringes on the interest of the speculative reason to this extent (261), that it removes the bounds which this latter had set to itself, and gives it up to every nonsense or delusion of imagination?
In fact, so far as practical reason is taken as dependent on pathological conditions, that is, as merely regulating the inclinations under the sensible principle of happiness, we could not require speculative reason to take its principles from such a source. Mohammed’s paradise, or the absorption into the Deity of the theosophists and mystics, would press their monstrosities on the reason according to the taste of each, and one might as well have no reason as surrender it in such fashion to all sorts of dreams. But if pure reason of itself can be practical and is actually so, as the consciousness of the moral law proves, then it is still only one and the same reason which, whether in a theoretical or a practical point of view, judges according to à priori principles; and then it is clear that although it is in the first point of view incompetent to establish certain propositions positively, which, however, do not contradict it, then as soon as these propositions are inseparably attached to the practical interest of pure reason, then it must accept them, though it be as something offered to it from a foreign source, something that has not grown on its own ground, but yet is sufficiently authenticated; and it must try to compare and connect them with everything that it has in its power as speculative reason. It must remember, however, that these are not additions to its insight, but yet are extensions of its employment in another, namely, a practical aspect; and this is not in the least opposed to its interest, which consists in the restriction of wild speculation.
Thus, when pure speculative and pure practical reason are combined in one cognition, the latter has the primacy, provided namely, that this combination is not contingent and arbitrary, but founded à priori on reason itself and therefore necessary (262). For without this subordination there would arise a conflict of reason with itself; since if they were merely co-ordinate, the former would close its boundaries strictly and admit nothing from the latter into its domain, while the latter would extend its bounds over everything, and when its needs required would seek to embrace the former within them. Nor could we reverse the order, and require pure practical reason to be subordinate to the speculative, since all interest is ultimately practical, and even that of speculative reason is conditional, and it is only in the practical employment of reason that it is complete.
—The Immortality of the Soul as a Postulate of Pure Practical Reason.
The realization of the summum bonum in the world is the necessary object of a will determinable by the moral law. But in this will the perfect accordance of the mind with the moral law is the supreme condition of the summum bonum. This then must be possible, as well as its object, since it is contained in the command to promote the latter. Now, the perfect accordance of the will with the moral law is holiness, a perfection of which no rational being of the sensible world is capable at any moment of his existence. Since, nevertheless, it is required as practically necessary, it can only be found in a progress in infinitum towards that perfect accordance, and on the principles of pure practical reason it is necessary (263) to assume such a practical progress as the real object of our will.
Now, this endless progress is only possible on the supposition of an endless duration of the existence and personality of the same rational being (which is called the immortality of the soul). The summum bonum, then, practically is only possible on the supposition of the immortality of the soul; consequently this immortality, being inseparably connected with the moral law, is a postulate of pure practical reason) by which I mean a theoretical proposition, not demonstrable as such, but which is an inseparable result of an unconditional à priori practical law). 1
This principle of the moral destination of our nature, namely, that it is only in an endless progress that we can attain perfect accordance with the moral law, is of the greatest use, not merely for the present purpose of supplementing the impotence of speculative reason, but also with respect to religion. In default of it, either the moral law is quite degraded from its holiness, being made out to be indulgent, and conformable to our convenience, or else men strain their notions of their vocation and their expectation to an unattainable goal, hoping to acquire complete holiness of will, and so they lose themselves in fanatical theosophic dreams, which wholly contradict self-knowledge. In both cases the unceasing effort to obey punctually and thoroughly a strict and inflexible command of reason, which yet is not ideal but real, is only hindered. For a rational but finite being, the only thing possible is an endless progress from the lower to higher degrees of moral perfection. The Infinite Being, to whom the condition of time is nothing (264), sees in this to us endless succession a whole of accordance with the moral law; and the holiness which His command inexorably requires, in order to be true to His justice in the share which He assigns to each in the summum bonum, is to be found in a single intellectual intuition of the whole existence of rational beings. All that can be expected of the creature in respect of the hope of this participation would be the consciousness of his tried character, by which, from the progress he has hitherto made from the worse to the morally better, and the immutability of purpose which has thus become known to him, he may hope for a further unbroken continuance of the same, however long his existence may last, even beyond this life, 1 and thus he may hope, not indeed here, nor at any imaginable point of his future existence, but only in the endlessness of his duration (which God alone can survey) (265) to be perfectly adequate to his will (without indulgence or excuse, which do not harmonize with justice).
—The Existence of God as a Postulate of Pure Practical Reason.
In the foregoing analysis the moral law led to a practical problem which is prescribed by pure reason alone, without the aid of any sensible motives, namely, that of the necessary completeness of the first and principal element of the summum bonum, viz. Morality; and as this can be perfectly solved only in eternity, to the postulate of immortality. The same law must also lead us to affirm the possibility of the second element of the summum bonum, viz. Happiness proportioned to that morality, and this on grounds as disinterested as before, and solely from impartial reason; that is, it must lead to the supposition of the existence of a cause adequate to this effect; in other words, it must postulate the existence of God, as the necessary condition of the possibility of the summum bonum (an object of the will which is necessarily connected with the moral legislation of pure reason). We proceed to exhibit this connexion in a convincing manner.
Happiness is the condition of a rational being in the world with whom everything goes according to his wish and will; it rests, therefore, on the harmony of physical nature with his whole end, and likewise with the essential determining principle of his will. Now the moral law as a law of freedom commands by determining principles (266), which ought to be quite independent on nature and on its harmony with our faculty of desire (as springs). But the acting rational being in the world is not the cause of the world and of nature itself. There is not the least ground, therefore, in the moral law for a necessary connexion between morality and proportionate happiness in a being that belongs to the world as part of it, and therefore dependent on it, and which for that reason cannot by his will be a cause of this nature, nor by his own power make it thoroughly harmonize, as far as his happiness is concerned, with his practical principles. Nevertheless, in the practical problem of pure reason, i.e. the necessary pursuit of the summum bonum, such a connexion is postulated as necessary: we ought to endeavour to promote the summum bonum, which, therefore, must be possible. Accordingly, the existence of a cause of all nature, distinct from nature itself and containing the principle of this connexion, namely, of the exact harmony of happiness with morality, is also postulated. Now, this supreme cause must contain the principle of the harmony of nature, not merely with a law of the will of rational beings, but with the conception of this law, in so far as they make it the supreme determining principle of the will, and consequently not merely with the form of morals, but with their morality as their motive, that is, with their moral character. Therefore, the summum bonum is possible in the world only on the supposition of a supreme Being 1 having a causality corresponding to moral character. Now a being that is capable of acting on the conception of laws is an intelligence (a rational being), and the causality of such a being according to this conception of laws is his will; therefore the supreme cause of nature, which must be presupposed as a condition of the summum bonum (267), is a being which is the cause of nature by intelligence and will, consequently its author, that is God. It follows that the postulate of the possibility of the highest derived good (the best world) is likewise the postulate of the reality of a highest original good, that is to say, of the existence of God. Now it was seen to be a duty for us to promote the summum bonum; consequently it is not merely allowable, but it is a necessity connected with duty as a requisite, that we should presuppose the possibility of this summum bonum; and as this is possible only on condition of the existence of God, it inseparably connects the supposition of this with duty; that is, it is morally necessary to assume the existence of God.
It must be remarked here that this moral necessity is subjective, that is, it is a want, and not objective, that is, itself a duty, for there cannot be a duty to suppose the existence of anything (since this concerns only the theoretical employment of reason). Moreover it is not meant by this that it is necessary to suppose the existence of God as a basis of all obligation in general (for this rests, as has been sufficiently proved, simply on the autonomy of reason itself). What belongs to duty here is only the endeavour to realize and promote the summum bonum in the world, the possibility of which can therefore be postulated; and as our reason finds it not conceivable except on the supposition of a supreme intelligence, the admission of this existence is therefore connected with the consciousness of our duty, although the admission itself belongs to the domain of speculative reason. Considered in respect of this alone, as a principle of explanation, it may be called a hypothesis, but in reference to the intelligibility of an object given us by the moral law (the summum bonum), and consequently of a requirement for practical purposes, it may be called faith, that is to say a pure rational faith, since pure reason (268) (both in its theoretical and its practical use) is the sole source from which it springs.
From this deduction it is now intelligible why the Greek schools could never attain the solution of their problem of the practical possibility of the summum bonum, because they made the rule of the use which the will of man makes of his freedom the sole and sufficient ground of this possibility, thinking that they had no need for that purpose of the existence of God. No doubt they were so far right that they established the principle of morals of itself independently on this postulate, from the relation of reason only to the will, and consequently made it the supreme practical condition of the summum bonum; but it was not therefore the whole condition of its possibility. The Epicureans had indeed assumed as the supreme principle of morality a wholly false one, namely that of happiness, and had substituted for a law a maxim of arbitrary choice according to every man’s inclination; they proceeded, however, consistently enough in this, that they degraded their summum bonum likewise just in proportion to the meanness of their fundamental principle, and looked for no greater happiness than can be attained by human prudence (including temperance and moderation of the inclinations), and this as we know would be scanty enough and would be very different according to circumstances; not to mention the exceptions that their maxims must perpetually admit and which make them incapable of being laws. The Stoics, on the contrary, had chosen their supreme practical principle quite rightly, making virtue the condition of the summum bonum; but when they represented the degree of virtue required by its pure law as fully attainable in this life, they not only strained the moral powers of the man whom they called the wise beyond all the limits of his nature, and assumed (269) a thing that contradicts all our knowledge of men, but also and principally they would not allow the second element of the summum bonum, namely, happiness, to be properly a special object of human desire, but made their wise man, like a divinity in his consciousness of the excellence of his person, wholly independent on nature (as regards his own contentment); they exposed him indeed to the evils of life, but made him not subject to them (at the same time representing him also as free from moral evil). They thus in fact left out the second element of the summum bonum, namely, personal happiness, placing it solely in action and satisfaction with one’s own personal worth, thus including it in the consciousness of being morally minded, in which they might have been sufficiently refuted by the voice of their own nature.
The doctrine of Christianity, 1 even if we do not yet consider it as a religious doctrine, gives, touching this point (269), a conception of the summum bonum (the kingdom of God), which alone satisfies the strictest demand of practical reason. The moral law is holy (unyielding) and demands holiness of morals, although all the moral perfection to which man can attain is still only virtue, that is, a rightful disposition arising from respect for the law, implying consciousness of a constant propensity to transgression, or at least a want of purity, that is, a mixture of many spurious (not moral) motives of obedience to the law, consequently a self-esteem combined with humility. In respect then of the holiness which the Christian law requires, this leaves the creature nothing but a progress in infinitum, but for that very reason it justifies him in hoping for an endless duration of his existence. The worth of a character perfectly accordant with the moral law is infinite, since (270) the only restriction on all possible happiness in the judgment of a wise and all-powerful distributor of it is the absence of conformity of rational beings to their duty. But the moral law of itself does not promise any happiness, for according to our conceptions of an order of nature in general, this is not necessarily connected with obedience to the law. Now Christian morality supplies this defect (of the second indispensable element of the summum bonum) by representing the world, in which rational beings devote themselves with all their soul to the moral law, as a kingdom of God, in which nature and morality are brought into a harmony foreign to each of itself, by a holy Author who makes the derived summum bonum possible. Holiness of life is prescribed to them as a rule even in this life, while the welfare proportioned to it, namely, bliss, is represented as attainable only in an eternity; because the former must always be the pattern of their conduct in every state, and progress towards it is already possible and necessary in this life; while the latter, under the name of happiness, cannot be attained at all in this world (so far as our own power is concerned), and therefore is made simply an object of hope. Nevertheless, the Christian principle of morality itself is not theological (so as to be heteronomy) but is autonomy of pure practical reason, since it does not make the knowledge of God and his will the foundation of these laws, but only of the attainment of the summum bonum, on condition of following these laws, and it does not even place the proper spring of this obedience in the desired results, but solely in the conception of duty, as that of which the faithful observance alone constitutes the worthiness to obtain those happy consequences.
In this manner the moral laws lead through the conception of the summum bonum as the object and final end of pure practical reason to religion (271), that is, to the recognition of all duties as divine commands, not as sanctions,1that is to say, arbitrary ordinances of a foreign will and contingent in themselves, but as essential laws of every free will in itself, which, nevertheless, must be regarded as commands of the Supreme Being, because it is only from a morally perfect (holy and good) and at the same time all-powerful will, and consequently only through harmony with this will that we can hope to attain the summum bonum which the moral law makes it our duty to take as the object of our endeavours. Here again, then, all remains disinterested and founded merely on duty; neither fear nor hope being made the fundamental springs, which if taken as principles would destroy the whole moral worth of actions. The moral law commands me to make the highest possible good in a world the ultimate object of all my conduct. But I cannot hope to effect this otherwise than by the harmony of my will with that of a holy and good Author of the world; and although the conception of the summum bonum as a whole, in which the greatest happiness is conceived as combined in the most exact proportion with the highest degree of moral perfection (possible in creatures), includes my own happiness, yet it is not this that is the determining principle of the will which is enjoined to promote the summum bonum, but the moral law, which on the contrary limits by strict conditions my unbounded desire of happiness.
Hence also morality is not properly the doctrine how we should make ourselves happy, but how we should become worthy of happiness. It is only when religion is added that there also comes in the hope of participating some day in happiness in proportion as we have endeavoured to be not unworthy of it.
 A man is worthy to possess a thing or a state when his possession of it is in harmony with the summum bonum. We can now easily see that all worthiness depends on moral conduct, since in the conception of the summum bonum this constitutes the condition of the rest (which belongs to one’s state), namely, the participation of happiness. Now it follows from this that morality should never be treated as a doctrine of happiness, that is, an instruction how to become happy; for it has to do simply with the rational condition (conditio sine qua non) of happiness, not with the means of attaining it. But when morality has been completely expounded (which merely imposes duties instead of providing rules for selfish desires), then, first, after the moral desire to promote the summum bonum (to bring the kingdom of God to us) has been awakened, a desire founded on a law, and which could not previously arise in any selfish mind, and when for the behoof of this desire the step to religion has been taken, then this ethical doctrine may be also called a doctrine of happiness, because the hope of happiness first begins with religion only.
We can also see from this that, when we ask what is God’s ultimate end in creating the world, we must not name the happiness of the rational beings in it, but the summum bonum, which adds a further condition to that wish of such beings, namely, the condition of being worthy of happiness, that is, the morality of these same rational beings, a condition which alone contains the rule by which only they can hope to share in the former at the hand of a wise Author. For as wisdom theoretically considered signifies the knowledge of the summum bonum, and practically the accordance of the will with the summum bonum, we cannot attribute to a supreme independent wisdom an end based merely on goodness (273). For we cannot conceive the action of this goodness (in respect of the happiness of rational beings) as suitable to the highest original good, except under the restrictive conditions of harmony with the holiness 1 of his will. Therefore those who placed the end of creation in the glory of God (provided that this is not conceived anthropomorphically as a desire to be praised) have perhaps hit upon the best expression. For nothing glorifies God more than that which is the most estimable thing in the world, respect for His command, the observance of the holy duty that His law imposes on us, when there is added thereto His glorious plan of crowning such a beautiful order of things with corresponding happiness. If the latter (to speak humanly) makes Him worthy of love, by the former He is an object of adoration. Even men can never acquire respect by benevolence alone, though they may gain love, so that the greatest beneficence only procures them honour when it is regulated by worthiness.
That in the order of ends, man (and with him every rational being) is an end in himself, that is, that he can never be used merely as a means by any (274) (not even by God) without being at the same time an end also himself, that therefore humanity in our person must be holy to ourselves, this follows now of itself because he is the subject1of the moral law, in other words, of that which is holy in itself, and on account of which and in agreement with which alone can anything be termed holy. For this moral law is founded on the autonomy of his will, as a free will which by its universal laws must necessarily be able to agree with that to which it is to submit itself.
—Of the Postulates of Pure Practical Reason in General.
They all proceed from the principle of morality, which is not a postulate but a law, by which reason determines the will directly, which will, because it is so determined as a pure will, requires these necessary conditions of obedience to its precept. These postulates are not theoretical dogmas, but suppositions practically necessary; while then they do [not] 2 extend our speculative knowledge, they give objective reality to the ideas of speculative reason in general (by means of their reference to what is practical), and give it a right to concepts, the possibility even of which it could not otherwise venture to affirm.
These postulates are those of immortality, freedom positively considered (as the causality of a being so far as he belongs to the intelligible world), and the existence of God. The first results from the practically necessary condition of a duration (275) adequate to the complete fulfilment of the moral law; the second from the necessary supposition of independence on the sensible world, and of the faculty of determining one’s will according to the law of an intelligible world, that is, of freedom; the third from the necessary condition of the existence of the summum bonum in such an intelligible world, by the supposition of the supreme independent good, that is, the existence of God.
Thus the fact that respect for the moral law necessarily makes the summum bonum an object of our endeavours, and the supposition thence resulting of its objective reality, lead through the postulates of practical reason to conceptions which speculative reason might indeed present as problems, but could never solve. Thus it leads—1. To that one in the solution of which the latter could do nothing but commit paralogisms (namely, that of immortality), because it could not lay hold of the character of permanence, by which to complete the psychological conception of an ultimate subject necessarily ascribed to the soul in self-consciousness, so as to make it the real conception of a substance, a character which practical reason furnishes by the postulate of a duration required for accordance with the moral law in the summum bonum, which is the whole end of practical reason. 2. It leads to that of which speculative reason contained nothing but antinomy, the solution of which it could only found on a notion problematically conceivable indeed, but whose objective reality it could not prove or determine, namely, the cosmological idea of an intelligible world and the consciousness of our existence in it, by means of the postulate of freedom (the reality of which it lays down by virtue of the moral law), and with it likewise the law of an intelligible world, to which speculative reason could only point, but could not define its conception. 3. What speculative reason was able to think, but was obliged to leave undetermined as a mere transcendental ideal (276), viz. the theological conception of the first Being, to this it gives significance (in a practical view, that is, as a condition of the possibility of the object of a will determined by that law), namely, as the supreme principle of the summum bonum in an intelligible world, by means of moral legislation in it invested with sovereign power.
Is our knowledge, however, actually extended in this way by pure practical reason, and is that immanent in practical reason which for the speculative was only transcendent? Certainly, but only in a practical point of view. For we do not thereby take knowledge of the nature of our souls, nor of the intelligible world, nor of the Supreme Being, with respect to what they are in themselves, but we have merely combined the conceptions of them in the practical concept of the summum bonum as the object of our will, and this altogether à priori, but only by means of the moral law, and merely in reference to it, in respect of the object which it commands. But how freedom is possible, and how we are to conceive this kind of causality theoretically and positively, is not thereby discovered; but only that there is such a causality is postulated by the moral law and in its behoof. It is the same with the remaining ideas, the possibility of which no human intelligence will ever fathom, but the truth of which, on the other hand, no sophistry will ever wrest from the conviction even of the commonest man.
—How is it possible to conceive an extension of Pure Reason in a Practical point of view, without its Knowledge as Speculative being enlarged at the same time?
In order not to be too abstract, we will answer this question at once in its application to the present case. In order to extend a pure cognition practically, there must be an à priori purpose given, that is, an end as object (of the will), which independently on all theological principle is presented as practically necessary by an imperative which determines the will directly (a categorical imperative), and in this case that is the summum bonum. This, however, is not possible without presupposing three theoretical conceptions (for which, because they are mere conceptions of pure reason, no corresponding intuition can be found, nor consequently by the path of theory any objective reality); namely, freedom, immortality, and God. Thus by the practical law which commands the existence of the highest good possible in a world, the possibility of those objects of pure speculative reason is postulated, and the objective reality which the latter could not assure them. By this the theoretical knowledge of pure reason does indeed obtain an accession; but it consists only in this, that those concepts which otherwise it had to look upon as problematical (merely thinkable) concepts, are now shown assertorially to be such as actually have objects; because practical reason indispensably requires their existence for the possibility of its object, the summum bonum, which practically is absolutely necessary, and this justifies theoretical reason in assuming them. But this extension of theoretical reason (278) is no extension of speculative, that is, we cannot make any positive use of it in a theoretical point of view. For as nothing is accomplished in this by practical reason, further than that these concepts are real and actually have their (possible) objects, and nothing in the way of intuition of them is given thereby (which indeed could not be demanded), hence the admission of this reality does not render any synthetical proposition possible. Consequently this discovery does not in the least help us to extend this knowledge of ours in a speculative point of view, although it does in respect of the practical employment of pure reason. The above three ideas of speculative reason are still in themselves not cognitions; they are however (transcendent) thoughts, in which there is nothing impossible. Now, by help of an apodictic practical law, being necessary conditions of that which it commands to be made an object, they acquire objective reality: that is, we learn from it that they have objects, without being able to point out how the conception of them is related to an object, and this, too, is still not a cognition of these objects; for we cannot thereby form any synthetical judgment about them, nor determine their application theoretically; consequently we can make no theoretical rational use of them at all, in which use all speculative knowledge of reason consists. Nevertheless, the theoretical knowledge, not indeed of these objects, but of reason generally, is so far enlarged by this, that by the practical postulates objects were given to those ideas, a merely problematical thought having by this means first acquired objective reality. There is therefore no extension of the knowledge of given supersensible objects, but an extension of theoretical reason and of its knowledge in respect of the supersensible generally; inasmuch as it is compelled to admit that there are such objects (279), although it is not able to define them more closely, so as itself to extend this knowledge of the objects (which have now been given it on practical grounds, and only for practical use). For this accession, then, pure theoretical reason, for which all those ideas are transcendent and without object, has simply to thank its practical faculty. In this they become immanent and constitutive, being the source of the possibility of realizing the necessary object of pure practical reason (the summum bonum); whereas apart from this they are transcendent, and merely regulative principles of speculative reason, which do not require it to assume a new object beyond experience, but only to bring its use in experience nearer to completeness. But when once reason is in possession of this accession, it will go to work with these ideas as speculative reason (properly only to assure the certainty of its practical use) in a negative manner: that is, not extending but clearing up its knowledge so as on one side to keep off anthropomorphism, as the source of superstition, or seeming extension of these conceptions by supposed experience; and on the other side fanaticism, which promises the same by means of supersensible intuition or feelings of the like kind. All these are hindrances to the practical use of pure reason, so that the removal of them may certainly be considered an extension of our knowledge in a practical point of view, without contradicting the admission that for speculative purposes reason has not in the least gained by this.
Every employment of reason in respect of an object requires pure concepts of the understanding (categories), without which no object can be conceived. These can be applied to the theoretical employment of reason, i. e. to that kind of knowledge, only in case an intuition (which is always sensible) is taken as a basis, and therefore merely in order (280) to conceive by means of them an object of possible experience. Now here what have to be thought by means of the categories, in order to be known, are ideas of reason, which cannot be given in any experience. Only we are not here concerned with the theoretical knowledge of the objects of these ideas, but only with this, whether they have objects at all. This reality is supplied by pure practical reason, and theoretical reason has nothing further to do in this but to think those objects by means of categories. This, as we have elsewhere clearly shown, can be done well enough without needing any intuition (either sensible or supersensible), because the categories have their seat and origin in the pure understanding, simply as the faculty of thought, before and independently on any intuition, and they always only signify an object in general, no matter in what way it may be given to us. Now when the categories are to be applied to these ideas, it is not possible to give them any object in intuition; but that such an object actually exists, and consequently that the category as a mere form of thought is here not empty but has significance, this is sufficiently assured them by an object which practical reason presents beyond doubt in the concept of the summum bonum, namely, the reality of the conceptions which are required for the possibility of the summum bonum, without, however, effecting by this accession the least extension of our knowledge on theoretical principles.
When these ideas of God, of an intelligible world (the kingdom of God), and of immortality are further determined by predicates taken from our own nature, we must not regard this determination as a sensualizing of those pure rational ideas (281) (anthropomorphism), nor as a transcendent knowledge of supersensible objects; for these predicates are no others than understanding and will, considered too in the relation to each other in which they must be conceived in the moral law, and therefore only so far as a pure practical use is made of them. As to all the rest that belongs to these conceptions psychologically, that is, so far as we observe these faculties of ours empirically in their exercise (e.g. that the understanding of man is discursive, and its notions therefore not intuitions but thoughts, that these follow one another in time, that his will has its satisfaction always dependent on the existence of its object, &c., which cannot be the case in the Supreme Being), from all this we abstract in that case, and then there remains of the notions by which we conceive a pure intelligence nothing more than just what is required for the possibility of conceiving a moral law. There is then a knowledge of God indeed, but only for practical purposes, and if we attempt to extend it to a theoretical knowledge we find an understanding that has intuitions, not thoughts, a will that is directed to objects on the existence of which its satisfaction does not in the least depend (not to mention the transcendental predicates, as, for example, a magnitude of existence, that is duration, which, however, is not in time, the only possible means we have of conceiving existence as magnitude). Now these are all attributes of which we can form no conception that would help to the knowledge of the object, and we learn from this that they can never be used for a theory of supersensible beings, so that on this side they are quite incapable of being the foundation of a speculative knowledge, and their use is limited simply to the practice of the moral law.
(282) This last is so obvious, and can be proved so clearly by fact, that we may confidently challenge all pretended natural theologians (a singular name) 1 to specify (over and above the merely ontological predicates) one single attribute, whether of the understanding or of the will, determining this object of theirs, of which we could not show incontrovertibly that if we abstract from it everything anthropomorphic, nothing would remain to us but the mere word, without our being able to connect with it the smallest notion by which we could hope for an extension of theoretical knowledge. But as to the practical, there still remains to us of the attributes of understanding and will the conception of a relation to which objective reality is given by the practical law (which determines à priori precisely this relation of the understanding to the will). When once this is done, then reality is given to the conception of the object of a will morally determined (the conception of the summum bonum), and with it to the conditions of its possibility, the ideas of God, freedom, and immortality, but always only relatively to the practice of the moral law (and not for any speculative purpose).
According to these remarks it is now easy to find the answer to the weighty question: whether the notion of God is one belonging to Physics (and therefore also to Metaphysics (283), which contains the pure à priori principles of the former in their universal import) or to morals. If we have recourse to God as the Author of all things, in order to explain the arrangements of nature or its changes, this is at least not a physical explanation, and is a complete confession that our philosophy has come to an end, since we are obliged to assume something of which in itself we have otherwise no conception, in order to be able to frame a conception of the possibility of what we see before our eyes. Metaphysics, however, cannot enable us to attain by certain inference from the knowledge of this world to the conception of God and to the proof of his existence, for this reason, that in order to say that this world could be produced only by a God (according to the conception implied by this word) we should know this world as the most perfect whole possible; and for this purpose should also know all possible worlds (in order to be able to compare them with this); in other words, we should be omniscient. It is absolutely impossible, however, to know the existence of this Being from mere concepts, because every existential proposition, that is every proposition that affirms the existence of a being of which I frame a concept, is a synthetic proposition, that is, one by which I go beyond that conception and affirm of it more than was thought in the conception itself, namely, that this concept in the understanding has an object corresponding to it outside the understanding, and this it is obviously impossible to elicit by any reasoning. There remains, therefore, only one single process possible for reason to attain this knowledge, namely, to start from the supreme principle of its pure practical use (which in every case is directed simply to the existence of something as a consequence of reason), and thus determine its object. Then its inevitable problem, namely, the necessary direction of the will to the summum bonum, discovers to us not only the necessity of assuming such a First Being (284) in reference to the possibility of this good in the world, but what is most remarkable, something which reason in its progress on the path of physical nature altogether failed to find, namely, an accurately defined conception of this First Being. As we can know only a small part of this world, and can still less compare it with all possible worlds, we may indeed from its order, design, and greatness, infer a wise, good, powerful, &c., Author of it, but not that He is all-wise, all-good, all-powerful, &c. It may indeed, very well be granted that we should be justified in supplying this inevitable defect by a legitimate and reasonable hypothesis, namely, that when wisdom, goodness, &c., are displayed in all the parts that offer themselves to our nearer knowledge, it is just the same in all the rest, and that it would therefore be reasonable to ascribe all possible perfections to the Author of the world, but these are not strict logical inferences in which we can pride ourselves on our insight, but only permitted conclusions in which we may be indulged, and which require further recommendation before we can make use of them. On the path of empirical inquiry then (physics) the conception of God remains always a conception of the perfection of the First Being not accurately enough determined to be held adequate to the conception of Deity. (With metaphysic in its transcendental part nothing whatever can be accomplished).
When I now try to test this conception by reference to the object of practical reason, I find that the moral principle admits as possible only the conception of an Author of the world possessed of the highest perfection. He must be omniscient, in order to know my conduct up to the inmost root of my mental state in all possible cases and into all future time; omnipotent, in order to allot to it its fitting consequences; similarly He must be omnipresent, eternal, &c. Thus the moral law, by means of the conception of the summum bonum (285) as the object of a pure practical reason, determines the concept of the First Being as the Supreme Being; a thing which the physical (and in its higher development the metaphysical); in other words, the whole speculative course of reason, was unable to effect. The conception of God, then, is one that belongs originally not to physics, i. e. to speculative reason, but to morals. The same may be said of the other conceptions of reason of which we have treated above as postulates of it in its practical use.
In the history of Grecian philosophy we find no distinct traces of a pure rational theology earlier than Anaxagoras, but this is not because the older philosophers had not intelligence or penetration enough to raise themselves to it by the path of speculation, at least with the aid of a thoroughly reasonable hypothesis. What could have been easier, what more natural, than the thought which of itself occurs to every one, to assume instead of several causes of the world, instead of an indeterminate degree of perfection, a single rational cause having all perfection? But the evils in the world seemed to them to be much too serious objections to allow them to feel themselves justified in such a hypothesis. They showed intelligence and penetration then in this very point, that they did not allow themselves to adopt it, but on the contrary looked about amongst natural causes to see if they could not find in them the qualities and power required for a First Being. But when this acute people had advanced so far in their investigations of nature as to treat even moral questions philosophically, on which other nations had never done anything but talk, then first they found a new and practical want, which did not fail to give definiteness to their conception of the First Being: and in this the speculative reason played the part of spectator, or at best had the merit of embellishing a conception that had not grown on its own ground, and of applying a series of confirmations (286) from the study of nature now brought forward for the first time, not indeed to strengthen the authority of this conception (which was already established), but rather to make a show with a supposed discovery of theoretical reason.
From these remarks the reader of the Critique of Pure Speculative Reason will be thoroughly convinced how highly necessary that laborious deduction of the categories was, and how fruitful for theology and morals. For if, on the one hand, we place them in the pure understanding, it is by this deduction alone that we can be prevented from regarding them, with Plato, as innate, and founding on them extravagant pretensions to theories of the supersensible, to which we can see no end, and by which we should make theology a magic lantern of chimera: on the other hand, if we regard them as acquired, this deduction saves us from restricting, with Epicurus, all and every use of them, even for practical purposes, to the objects and motives of the senses. But now that the Critique has shown by that deduction, first, that they are not of empirical origin, but have their seat and source à priori in the pure understanding; secondly, that as they refer to objects in general independently on the intuition of them, hence, although they cannot effect theoretical knowledge, except in application to empirical objects, yet when applied to an object given by pure practical reason they enable us to conceive the supersensible definitely, only so far, however, as it is defined by such predicates as are necessarily connected with the pure practical purpose given à priori and with its possibility. The speculative restriction of pure reason and its practical extension bring it into that (287) relation of equality in which reason in general can be employed suitably to its end, and this example proves better than any other that the path to wisdom, if it is to be made sure and not to be impassable or misleading, must with us men inevitably pass through science; but it is not till this is completed that we can be convinced that it leads to this goal.
—Of Belief from a Requirement of Pure Reason.
A want or requirement of pure reason in its speculative use leads only to a hypothesis; that of pure practical reason to a postulate; for in the former case I ascend from the result as high as I please in the series of causes, not in order to give objective reality to the result (e. g. the causal connexion of things and changes in the world), but in order thoroughly to satisfy my inquiring reason in respect of it. Thus I see before me order and design in nature, and need not resort to speculation to assure myself of their reality, but to explain them I have to pre-suppose a Deity as their cause; and then since the inference from an effect to a definite cause is always uncertain and doubtful, especially to a cause so precise and so perfectly defined as we have to conceive in God, hence the highest degree of certainty to which this pre-supposition can be brought is, that it is the most rational opinion for us men 1 (288). On the other hand, a requirement of pure practical reason is based on a duty, that of making something (the summum bonum) the object of my will so as to promote it with all my powers; in which case I must suppose its possibility, and consequently also the conditions necessary thereto, namely, God, freedom, and immortality; since I cannot prove these by my speculative reason, although neither can I refute them. This duty is founded on something that is indeed quite independent on these suppositions, and is of itself apodictically certain, namely, the moral law; and so far it needs no further support by theoretical views as to the inner constitution of things, the secret final aim of the order of the world, or a presiding ruler thereof, in order to bind me in the most perfect manner to act in unconditional conformity to the law. But the subjective effect of this law, namely, the mental disposition conformed to it and made necessary by it, to promote the practically possible summum bonum, this pre-supposes at least that the latter is possible, for it would be practically impossible to strive after the object of a conception which at bottom was empty and had no object. Now the above-mentioned postulates concern only the physical or metaphysical conditions of the possibility of the summum bonum (289); in a word, those which lie in the nature of things; not, however, for the sake of an arbitrary speculative purpose, but of a practically necessary end of a pure rational will, which in this case does not choose, but obeys an inexorable command of reason, the foundation of which is objective, in the constitution of things as they must be universally judged by pure reason, and is not based on inclination; for we are in nowise justified in assuming, on account of what we wish on merely subjective grounds, that the means thereto are possible or that its object is real. This then is an absolutely necessary requirement, and what it pre-supposes is not merely justified as an allowable hypothesis, but as a postulate in a practical point of view; and admitting that the pure moral law inexorably binds every man as a command (not as a rule of prudence), the righteous man may say: I will that there be a God, that my existence in this world be also an existence outside the chain of physical causes, and in a pure world of the understanding, and lastly, that my duration be endless; I firmly abide by this, and will not let this faith be taken from me; for in this instance alone my interest, because I must not relax anything of it, inevitably determines my judgment, without regarding sophistries, however unable I may be to answer them or to oppose them with others more plausible. 1
(290) In order to prevent misconception in the use of a notion as yet so unusual as that of a faith of pure practical reason, let me be permitted to add one more remark. It might almost seem as if this rational faith were here announced as itself a command, namely, that we should assume the summum bonum as possible. But a faith that is commanded is nonsense. Let the preceding analysis, however, be remembered of what is required to be supposed in the conception of the summum bonum, and it will be seen that it cannot be commanded to assume this possibility, and no practical disposition of mind is required to admit it; but that speculative reason must concede it without being asked, for no one can affirm that it is impossible in itself that rational beings in the world should at the same time be worthy of happiness in conformity with the moral law, and also possess this happiness proportionately. Now in respect of the first element of the summum bonum, namely, that which concerns morality, the moral law gives merely a command, and to doubt the possibility of that element would be the same as to call in question the moral law itself (291). But as regards the second element of that object, namely, happiness perfectly proportioned to that worthiness, it is true that there is no need of a command to admit its possibility in general, for theoretical reason has nothing to say against it; but the manner in which we have to conceive this harmony of the laws of nature with those of freedom has in it something in respect of which we have a choice, because theoretical reason decides nothing with apodictic certainty about it, and in respect of this there may be a moral interest which turns the scale.
I had said above that in a mere course of nature in the world an accurate correspondence between happiness and moral worth is not to be expected, and must be regarded as impossible, and that therefore the possibility of the summum bonum cannot be admitted from this side except on the supposition of a moral Author of the world. I purposely reserved the restriction of this judgment to the subjective conditions of our reason, in order not to make use of it until the manner of this belief should be defined more precisely. The fact is that the impossibility referred to is merely subjective, that is, our reason finds it impossible for it to render conceivable in the way of a mere course of nature a connexion so exactly proportioned and so thoroughly adapted to an end, between two sets of events happening according to such distinct laws; although, as with everything else in nature that is adapted to an end, it cannot prove, that is, show by sufficient objective reasons, that it is not possible by universal laws of nature.
Now, however, a deciding principle of a different kind comes into play to turn the scale in this uncertainty of speculative reason. The command to promote the summum bonum is established on an objective basis (in practical reason); the possibility of the same in general is likewise established on an objective basis (292) (in theoretical reason, which has nothing to say against it). But reason cannot decide objectively in what way we are to conceive this possibility; whether by universal laws of nature without a wise Author presiding over nature, or only on supposition of such an Author. Now here there comes in a subjective condition of reason; the only way theoretically possible for it, of conceiving the exact harmony of the kingdom of nature with the kingdom of morals, which is the condition of the possibility of the summum bonum; and at the same time the only one conducive to morality (which depends on an objective law of reason). Now since the promotion of this summum bonum, and therefore the supposition of its possibility, are objectively necessary (though only as a result of practical reason), while at the same time the manner in which we would conceive it rests with our own choice, and in this choice a free interest of pure practical reason decides for the assumption of a wise Author of the world; it is clear that the principle that herein determines our judgment, though as a want it is subjective, yet at the same time being the means of promoting what is objectively (practically) necessary, is the foundation of a maxim of belief in a moral point of view, that is, a faith of pure practical reason. This, then, is not commanded, but being a voluntary determination of our judgment, conducive to the moral (commanded) purpose, and moreover harmonizing with the theoretical requirement of reason, to assume that existence and to make it the foundation of our further employment of reason, it has itself sprung from the moral disposition of mind; it may therefore at times waver even in the well-disposed, but can never be reduced to unbelief.
—Of the Wise Adaptation of Man’s Cognitive Faculties to his Practical Destination.
If human nature is destined to endeavour after the summum bonum, we must suppose also that the measure of its cognitive faculties, and particularly their relation to one another, is suitable to this end. Now the Critique of Pure Speculative Reason proves that this is incapable of solving satisfactorily the most weighty problems that are proposed to it, although it does not ignore the natural and important hints received from the same reason, nor the great steps that it can make to approach to this great goal that is set before it, which, however, it can never reach of itself, even with the help of the greatest knowledge of nature. Nature then seems here to have provided us only in a step-motherly fashion with the faculty required for our end.
Suppose now that in this matter nature had conformed to our wish, and had given us that capacity of discernment or that enlightenment which we would gladly possess, or which some imagine they actually possess, what would in all probability be the consequence? Unless our whole nature were at the same time changed, our inclinations, which always have the first word, would first of all demand their own satisfaction, and, joined with rational reflection, the greatest possible and most lasting satisfaction, under the name of happiness; the moral law (294) would afterwards speak, in order to keep them within their proper bounds, and even to subject them all to a higher end, which has no regard to inclination. But instead of the conflict that the moral disposition has now to carry on with the inclinations, in which, though after some defeats, moral strength of mind may be gradually acquired, God and eternity with their awful majesty would stand unceasingly before our eyes (for what we can prove perfectly is to us as certain as that of which we are assured by the sight of our eyes). Transgression of the law would, no doubt, be avoided; what is commanded would be done; but the mental disposition, from which actions ought to proceed, cannot be infused by any command, and in this case the spur of action is ever active and external, so that reason has no need to exert itself in order to gather strength to resist the inclinations by a lively representation of the dignity of the law: hence most of the actions that conformed to the law would be done from fear, a few only from hope, and none at all from duty, and the moral worth of actions, on which alone in the eyes of supreme wisdom the worth of the person and even that of the world depends, would cease to exist. As long as the nature of man remains what it is, his conduct would thus be changed into mere mechanism, in which, as in a puppet show, everything would gesticulate well, but there would be no life in the figures. Now, when it is quite otherwise with us, when with all the effort of our reason we have only a very obscure and doubtful view into the future, when the Governor of the world allows us only to conjecture his existence and his majesty, not to behold them or prove them clearly; and on the other hand, the moral law within us, without promising or threatening anything with certainty, demands of us disinterested respect; and only when this respect has become active (295) and dominant does it allow us by means of it a prospect into the world of the supersensible, and then only with weak glances: all this being so, there is room for true moral disposition, immediately devoted to the law, and a rational creature can become worthy of sharing in the summum bonum that corresponds to the worth of his person and not merely to his actions. Thus what the study of nature and of man teaches us sufficiently elsewhere may well be true here also; that the unsearchable wisdom by which we exist is not less worthy of admiration in what it has denied than in what it has granted.
METHODOLOGY OF PURE PRACTICAL REASON.