II.2. The Canon of Pure Reason

It is humiliating to human reason that it achieves nothing in its pure employment, and indeed stands in need of a discipline to check its extravagances, and to guard it against the deceptions which arise therefrom. But, on the other hand, reason is reassured and gains self-confidence, on finding that it itself can and must apply this discipline, and that it is not called upon to submit to any outside censorship; and, moreover, that the limits which it is compelled to set to its speculative employment likewise limit the pseudo-rational pretensions of all its opponents, and that it can secure against all attacks whatever may remain over from its former exaggerated claims. The greatest and perhaps the sole use of all philosophy of pure reason is therefore only negative; since it serves not as an organon for the extension but as a discipline for the limitation of pure reason, and, instead of discovering truth, has only the modest merit of guarding against error.

There must, however, be some source of positive modes of knowledge which belong to the domain of pure reason, and which, it may be, give occasion to error solely owing to misunderstanding, while yet in actual fact they form the goal towards which reason is directing its efforts. How else can we account for our inextinguishable desire to find firm footing somewhere beyond the limits of experience? Reason has a presentiment of objects which possess a great interest for it. But when it follows the path of pure speculation, in order to approach them, they fly before it. Presumably it may look for better fortune in the only other path which still remains open to it, that of its practical employment.

I understand by a canon the sum-total of the a priori principles of the correct employment of certain faculties of knowledge. Thus general logic, in its analytic portion, is a canon for understanding and reason in general; but only in regard to their form; it abstracts from all content. The transcendental analytic has similarly been shown to be the canon of the pure understanding; for understanding alone is capable of true synthetic modes of knowledge a priori. But when no correct employment of a faculty of knowledge is possible there is no canon. Now all synthetic knowledge through pure reason in its speculative employment is, as has been shown by the proofs given, completely impossible. There is therefore no canon of its speculative employment; such employment is entirely dialectical. All transcendental logic is, in this respect, simply a discipline. Consequently, if there be any correct employment of pure reason, in which case there must be a canon of its employment, the canon will deal not with the speculative but with the practical employment of reason. This practical employment of reason we shall now proceed to investigate.

Reason is impelled by a tendency of its nature to go out beyond the field of its empirical employment, and to venture in a pure employment, by means of ideas alone, to the utmost limits of all knowledge, and not to be satisfied save through the completion of its course in [the apprehension of] a self-subsistent systematic whole. Is this endeavour the outcome merely of the speculative interests of reason? Must we not rather regard it as having its source exclusively in the practical interests of reason?

I shall, for the moment, leave aside all question as to the success which attends pure reason in its speculative exercise, and enquire only as to the problems the solution of which constitutes its ultimate aim, whether reached or not, and in respect of which all other aims are to be regarded only as means. These highest aims must, from the nature of reason, have a certain unity, in order that they may, as thus unified, further that interest of humanity which is subordinate to no higher interest.

The ultimate aim to which the speculation of reason in its transcendental employment is directed concerns three objects: the freedom of the will, the immortality of the soul, and the existence of God. In respect of all three the merely speculative interest of reason is very small; and for its sake alone we should hardly have undertaken the labour of transcendental investigation—a labour so fatiguing in its endless wrestling with insuperable difficulties—since whatever discoveries might be made in regard to these matters, we should not be able to make use of them in any helpful manner in concreto, that is, in the study of nature. If the will be free, this can have a bearing only on the intelligible cause of our volition. For as regards the phenomena of its outward expressions, that is, of our actions, we must account for them—in accordance with a maxim which is inviolable, and which is so fundamental that without it we should not be able to employ reason in any empirical manner whatsoever—in the same manner as all other appearances of nature, namely, in conformity with unchangeable laws. If, again, we should be able to obtain insight into the spiritual nature of the soul, and therewith of its immortality, we could make no use of such insight in explaining either the appearances of this present life or the specific nature of a future state. For our concept of an incorporeal nature is merely negative, and does not in the least extend our knowledge, yielding no sufficient material for inferences, save only such as are merely fictitious and cannot be sanctioned by philosophy. If, thirdly, the existence of a supreme intelligence be proved, by its means we might indeed render what is purposive in the constitution and ordering of the world comprehensible in a general sort of way, but we should not be in the least warranted in deriving from it any particular arrangement or disposition, or in boldly inferring any such, where it is not perceived. For it is a necessary rule of the speculative employment of reason, not to pass over natural causes, and, abandoning that in regard to which we can be instructed by experience, to deduce something which we know from something which entirely transcends all our [possible] knowledge. In short, these three propositions are for speculative reason always transcendent, and allow of no immanent employment—that is, employment in reference to objects of experience, and so in some manner really of service to us—but are in themselves, notwithstanding the very heavy labours which they impose upon our reason, entirely useless.

If, then, these three cardinal propositions are not in any way necessary for knowledge and are yet strongly recommended by our reason, their importance, properly regarded, must concern only the practical.

By ‘the practical’ I mean everything that is possible through freedom. When, however, the conditions of the exercise of our free will are empirical, reason can have no other than a regulative employment in regard to it, and can serve only to effect unity in its empirical laws. Thus, for instance, in the precepts of prudence, the whole business of reason consists in uniting all the ends which are prescribed to us by our desires in the one single end, happiness, and in coordinating the means for attaining it. In this field, therefore, reason can supply none but pragmatic laws of free action, for the attainment of those ends which are commended to us by the senses; it cannot yield us laws that are pure and determined completely a priori. Laws of this latter type, pure practical laws, whose end is given through reason completely a priori, and which are prescribed to us not in an empirically conditioned but in an absolute manner, would be products of pure reason. Such are the moral laws; and these alone, therefore, belong to the practical employment of reason, and allow of a canon.

The whole equipment of reason, in the discipline which may be entitled pure philosophy, is in fact determined with a view to the three above-mentioned problems. These, however, themselves in turn refer us yet further, namely, to the problem what we ought to do, if the will is free, if there is a God and a future world. As this concerns our attitude to the supreme end, it is evident that the ultimate intention of nature in her wise provision for us has indeed, in the constitution of our reason, been directed to moral interests alone.

But we must be careful, in turning our attention to an object which is foreign to transcendental philosophy, that we do not indulge in digressions to the detriment of the unity of the system, nor on the other hand, by saying too little on this new topic, fail in producing conviction through lack of clearness. I hope to avoid both dangers, by keeping as close as possible to the transcendental, and by leaving entirely aside any psychological, that is, empirical, factors that may perchance accompany it.

I must first remark that for the present I shall employ the concept of freedom in this practical sense only, leaving aside that other transcendental meaning which cannot be empirically made use of in explanation of appearances, but is itself a problem for reason, as has been already shown. A will is purely animal (arbitrium brutum), which cannot be determined save through sensuous impulses, that is, pathologically. A will which can be determined independently of sensuous impulses, and therefore through motives which are represented only by reason, is entitled freewill (arbitrium liberum), and everything which is bound up with this will, whether as ground or as consequence, is entitled practical, [The fact of] practical freedom can be proved through experience. For the human will is not determined by that alone which stimulates, that is, immediately affects the senses; we have the power to overcome the impressions on our faculty of sensuous desire, by calling up representations of what, in a more indirect manner, is useful or injurious. But these considerations, as to what is desirable in respect of our whole state, that is, as to what is good and useful, are based on reason. Reason therefore provides laws which are imperatives, that is, objective laws of freedom, which tell us what ought to happen—although perhaps it never does happen—therein differing from laws of nature, which relate only to that which happens. These laws are therefore to be entitled practical laws.

Whether reason is not, in the actions through which it prescribes laws, itself again determined by other influences, and whether that which, in relation to sensuous impulses, is entitled freedom, may not, in relation to higher and more remote operating causes, be nature again, is a question which in the practical field does not concern us, since we are demanding of reason nothing but the rule of conduct; it is a merely speculative question, which we can leave aside so long as we are considering what ought or ought not to be done. While we thus through experience know practical freedom to be one of the causes in nature, namely, to be a causality of reason in the determination of the will, transcendental freedom demands the independence of this reason—in respect of its causality, in beginning a series of appearances—from all determining causes of the sensible world. Transcendental freedom is thus, as it would seem, contrary to the law of nature, and therefore to all possible experience; and so remains a problem. But this problem does not come within the province of reason in its practical employment; and we have therefore in a canon of pure reason to deal with only two questions, which relate to the practical interest of pure reason, and in regard to which a canon of its employment must be possible—Is there a God? and, Is there a future life? The question of transcendental freedom is a matter for speculative knowledge only, and when we are dealing with the practical, we can leave it aside as being an issue with which we have no concern. Moreover, a quite sufficient discussion of it is to be found in the antinomy of pure reason.

Reason, in its speculative employment, conducted us through the field of experience, and since it could not find complete satisfaction there, from thence to speculative ideas, which, however, in the end brought us back to experience. In so doing the ideas fulfilled their purpose, but in a manner which, though useful, is not in accordance with our expectation. One other line of enquiry still remains open to us: namely, whether pure reason may not also be met with in the practical sphere, and whether it may not there conduct us to ideas which reach to those highest ends of pure reason that we have just stated, and whether, therefore, reason may not be able to supply to us from the standpoint of its practical interest what it altogether refuses to supply in respect of its speculative interest.

All the interests of my reason, speculative as well as practical, combine in the three following questions:

1. What can I know?

2. What ought I to do?

3. What may I hope?

The first question is merely speculative. We have, as I flatter myself, exhausted all the possible answers to it, and at last have found the answer with which reason must perforce content itself, and with which, so long as it takes no account of the practical, it has also good cause to be satisfied. But from the two great ends to which the whole endeavour of pure reason was really directed, we have remained just as far removed as if through love of ease we had declined this labour of enquiry at the very outset. So far, then, as knowledge is concerned, this much, at least, is certain and definitively established, that in respect of these two latter problems, knowledge is unattainable by us.

The second question is purely practical. As such it can indeed come within the scope of pure reason, but even so is not transcendental but moral, and cannot, therefore, in and by itself, form a proper subject for treatment in this Critique.

The third question—If I do what I ought to do, what may I then hope?—is at once practical and theoretical, in such fashion that the practical serves only as a clue that leads us to the answer to the theoretical question, and when this is followed out, to the speculative question. For all hoping is directed to happiness, and stands in the same relation to the practical and the law of morality as knowing and the law of nature to the theoretical knowledge of things. The former arrives finally at the conclusion that something is (which determines the ultimate possible end) because something ought to happen; the latter, that something is (which operates as the supreme cause) because something happens.

Happiness is the satisfaction of all our desires, extensively, in respect of their manifoldness, intensively, in respect of their degree, and protensively in respect of their duration. The practical law, derived from the motive of happiness, I term pragmatic (rule of prudence), and that law, if there is such a law, which has no other motive than worthiness of being happy, I term moral (law of morality). The former advises us what we have to do if we wish to achieve happiness; the latter dictates to us how we must behave in order to deserve happiness. The former is based on empirical principles; for only by means of experience can I know what desires there are which call for satisfaction; or what those natural causes are which are capable of satisfying them. The latter takes no account of desires, and the natural means of satisfying them, and considers only the freedom of a rational being in general, and the necessary conditions under which alone this freedom can harmonise with a distribution of happiness that is made in accordance with principles. This latter law can therefore be based on mere ideas of pure reason, and known a priori.

I assume that there really are pure moral laws which determine completely a priori (without regard to empirical motives, that is, to happiness) what is and is not to be done, that is, which determine the employment of the freedom of a rational being in general; and that these laws command in an absolute manner (not merely hypothetically, on the supposition of other empirical ends), and are therefore in every respect necessary. I am justified in making this assumption, in that I can appeal not only to the proofs employed by the most enlightened moralists, but to the moral judgment of every man, in so far as he makes the effort to think such a law clearly.

Pure reason, then, contains, not indeed in its speculative employment, but in that practical employment which is also moral, principles of the possibility of experience, namely, of such actions as, in accordance with moral precepts, might be met with in the history of mankind. For since reason commands that such actions should take place, it must be possible for them to take place. Consequently, a special kind of systematic unity, namely the moral, must likewise be possible. We have indeed found that the systematic unity of nature cannot be proved in accordance with speculative principles of reason. For although reason does indeed have causality in respect of freedom in general, it does not have causality in respect of nature as a whole; and although moral principles of reason can indeed give rise to free actions, they cannot give rise to laws of nature. Accordingly it is in their practical, meaning thereby their moral, employment, that the principles of pure reason have objective reality.

I entitle the world a moral worlds in so far as it may be in accordance with all moral laws; and this is what by means of the freedom of the rational being it can be, and what according to the necessary laws of morality it ought to be. Owing to our here leaving out of account all conditions (ends) and even all the special difficulties to which morality is exposed (weakness or depravity of human nature), this world is so far thought as an intelligible world only. To this extent, therefore, it is a mere idea, though at the same time a practical idea, which really can have, as it also ought to have, an influence upon the sensible world, to bring that world, so far as may be possible, into conformity with the idea. The idea of a moral world has, therefore, objective reality, not as referring to an object of an intelligible intuition (we are quite unable to think any such object), but as referring to the sensible world, viewed, however, as being an object of pure reason in its practical employment, that is, as a corpus mysticum of the rational beings in it, so far as the free will of each being is, under moral laws, in complete systematic unity with itself and with the freedom of every other.

This is the answer to the first of the two questions of pure reason that concern its practical interest:—Do that through which thou becomest worthy to be happy. The second question is:—If I so behave as not to be unworthy of happiness, may I hope thereby to obtain happiness? In answering this question we have to consider whether the principles of pure reason, which prescribe the law a priori, likewise connect this hope necessarily with it.

I maintain that just as the moral principles are necessary according to reason in its practical employment, it is in the view of reason, in the field of its theoretical employment, no less necessary to assume that everyone has ground to hope for happiness in the measure in which he has rendered himself by his conduct worthy of it, and that the system of morality is therefore inseparably—though only in the idea of pure reason—A bound up with that of happiness.

Now in an intelligible world, that is, in the moral world, in the concept of which we leave out of account all the hindrances to morality (the desires), such a system, in which happiness is bound up with and proportioned to morality, can be conceived as necessary, inasmuch as freedom, partly inspired and partly restricted by moral laws, would itself be the cause of general happiness, since rational beings, under the guidance of such principles, would themselves be the authors both of their own enduring well-being and of that of others. But such a system of self-rewarding morality is only an idea, the carrying out of which rests on the condition that everyone does what he ought, that is, that all the actions of rational beings take place just as if they had proceeded from a supreme will that comprehends in itself, or under itself, all private wills. But since the moral law remains binding for every one in the use of his freedom, even although others do not act in conformity with the law, neither the nature of the things of the world nor the causality of the actions themselves and their relation to morality determine how the consequences of these actions will be related to happiness. The alleged necessary connection of the hope of happiness with the necessary endeavour to render the self worthy of happiness cannot therefore be known through reason. It can be counted upon only if a Supreme Reason, that governs according to moral rules, be likewise posited as underlying nature as its cause.

The idea of such an intelligence in which the most perfect moral will, united with supreme blessedness, is the cause of all happiness in the world—so far as happiness stands in exact relation with morality, that is, with worthiness to be happy—I entitle the ideal of the supreme good. It is, therefore, only in the ideal of the supreme original good that pure reason can find the ground of this connection, which is necessary from the practical point of view, between the two elements of the supreme derivative good—the ground, namely, of an intelligible, that is, moral world. Now since we are necessarily constrained by reason to represent ourselves as belonging to such a world, while the senses present to us nothing but a world of appearances, we must assume that moral world to be a consequence of our conduct in the world of sense (in which no such connection between worthiness and happiness is exhibited), and therefore to be for us a future world. Thus God and a future life are two postulates which, according to the principles of pure reason, are inseparable from the obligation which that same reason imposes upon us.

Morality, by itself, constitutes a system. Happiness, however, does not do so, save in so far as it is distributed in exact proportion to morality. But this is possible only in the intelligible world, under a wise Author and Ruler. Such a Ruler, together with life in such a world, which we must regard as a future world, reason finds itself constrained to assume; otherwise it would have to regard the moral laws as empty figments of the brain, since without this postulate the necessary consequence which it itself connects with these laws could not follow. Hence also everyone regards the moral laws as commands; and this the moral laws could not be if they did not connect a priori suitable consequences with their rules, and thus carry with them promises and threats. But this again they could not do, if they did not reside in a necessary being, as the supreme good, which alone can make such a purposive unity possible.

Leibniz entitled the world, in so far as we take account only of the rational beings in it, and of their connection according to moral laws under the government of the supreme good, the kingdom of grace, distinguishing it from the kingdom of nature, in which these rational beings do indeed stand under moral laws, but expect no other consequences from their actions than such as follow in accordance with the course of nature in our world of sense. To view ourselves, therefore, as in the world of grace, where all happiness awaits us, except in so far as we ourselves limit our share in it through being unworthy of happiness, is, from the practical standpoint, a necessary idea of reason.

Practical laws, in so far as they are subjective grounds of actions, that is, subjective principles, are entitled maxims. The estimation of morality, in regard to its purity and consequences, is effected in accordance with ideas, the observance of its laws in accordance with maxims.

It is necessary that the whole course of our life be subject to moral maxims; but it is impossible that this should happen unless reason connects with the moral law, which is a mere idea, an operative cause which determines for such conduct as is in accordance with the moral law an outcome, either in this or in another life, that is in exact conformity with our supreme ends. Thus without a God and without a world invisible to us now but hoped for, the glorious ideas of morality are indeed objects of approval and admiration, but not springs of purpose and action. For they do not fulfil in its completeness that end which is natural to every rational being and which is determined a priori, and rendered necessary, by that same pure reason.

Happiness, taken by itself, is, for our reason, far from being the complete good. Reason does not approve happiness (however inclination may desire it) except in so far as it is united with worthiness to be happy, that is, with moral conduct. Morality, taken by itself, and with it, the mere worthiness to be happy, is also far from being the complete good. To make the good complete, he who behaves in such a manner as not to be unworthy of happiness must be able to hope that he will participate in happiness. Even the reason that is free from all private purposes, should it put itself in the place of a being that had to distribute all happiness to others, cannot judge otherwise; for in the practical idea both elements are essentially connected, though in such a manner that it is the moral disposition which conditions and makes possible the participation in happiness, and not conversely the prospect of happiness that makes possible the moral disposition. For in the latter case the disposition would not be moral, and therefore would not be worthy of complete happiness—happiness which in the view of reason allows of no limitation save that which arises from our own immoral conduct.

Happiness, therefore, in exact proportion with the morality of the rational beings who are thereby rendered worthy of it, alone constitutes the supreme good of that world wherein, in accordance with the commands of a pure but practical reason, we are under obligation to place ourselves. This world is indeed an intelligible world only, since the sensible world holds out no promise that any such systematic unity of ends can arise from the nature of things. Nor is the reality of this unity based on anything else than the postulate of a supreme original good. In a supreme good, thus conceived, self-subsistent reason, equipped with all the sufficiency of a supreme cause, establishes, maintains, and completes the universal order of things, according to the most perfect design—an order which in the world of sense is in large part concealed from us.

This moral theology has the peculiar advantage over speculative theology that it inevitably leads to the concept of a sole, all-perfect, and rational primordial being, to which speculative theology does not, on objective grounds, even so much as point the way, and as to the existence of which it is still less capable of yielding any conviction. For neither in transcendental nor in natural theology, however far reason may carry us, do we find any considerable ground for assuming only some one single being which we should be justified in placing prior to all natural causes, and upon which we might make them in all respects dependent. On the other hand, if we consider from the point of view of moral unity, as a necessary law of the world, what the cause must be that can alone give to this law its appropriate effect, and so for us obligatory force, we conclude that there must be one sole supreme will, which comprehends all these laws in itself. For how, under different wills, should we find complete unity of ends. This Divine Being must be omnipotent, in order that the whole of nature and its relation to morality in the world may be subject to his will; omniscient, that He may know our innermost sentiments and their moral worth; omnipresent, that He may be immediately at hand for the satisfying of every need which the highest good demands; eternal, that this harmony of nature and freedom may never fail, etc.

But this systematic unity of ends in this world of intelligences—a world which is indeed, as mere nature, a sensible world only, but which, as a system of freedom, can be entitled an intelligible, that is, a moral world (regnum gratiae leads inevitably also to the purposive unity of all things, which constitute this great whole, in accordance with universal laws of nature (just as the former unity is in accordance with universal and necessary laws of morality), and thus unites the practical with the speculative reason. The world must be represented as having originated from an idea if it is to be in harmony with that employment of reason without which we should indeed hold ourselves to be unworthy of reason, namely, with the moral employment—which is founded entirely on the idea of the supreme good. In this way all investigation of nature tends to take the form of a system of ends, and in its widest extension becomes a physico-theology. But this, as it has its source in the moral order, as a unity grounded in freedom’s own essential nature, and not accidentally instituted through external commands, connects the purposiveness of nature with grounds which must be inseparably connected a priori with the inner possibility of things, and so leads to a transcendental theology—a theology which takes the ideal of supreme ontological perfection as a principle of systematic unity. And since all things have their origin in the absolute necessity of the one primordial being, that principle connects them in accordance with universal and necessary laws of nature.

What use can we make of our understanding, even in respect of experience, if we do not propose ends to ourselves? But the highest ends are those of morality, and these we can know only as they are given us by pure reason. But though provided with these, and employing them as a clue, we cannot make use of the knowledge of nature in any serviceable manner in the building up of knowledge, unless nature has itself shown unity of design. For without this unity we should ourselves have no reason, inasmuch as there would be no school for reason, and no fertilisation through objects such as might afford materials for the necessary concepts. But the former purposive unity is necessary, and founded on the will’s own essential nature, and this latter unity [of design in nature] which contains the condition of its application in concreto, must be so likewise. And thus the transcendental enlargement of our knowledge, as secured through reason, is not to be regarded as the cause, but merely as the effect of the practical purposiveness which pure reason imposes upon us.

Accordingly we find, in the history of human reason, that until the moral concepts were sufficiently purified and determined, and until the systematic unity of their ends was understood in accordance with these concepts and from necessary principles, the knowledge of nature, and even a quite considerable development of reason in many other sciences, could give rise only to crude and incoherent concepts of the Deity, or as sometimes happened resulted in an astonishing indifference in regard to all such matters. A greater preoccupation with moral ideas, which was rendered necessary by the extraordinarily pure moral law of our religion, made reason more acutely aware of its object, through the interest which it was compelled to take in it. And this came about, independently of any influence exercised by more extended views of nature or by correct and reliable transcendental insight (for that has always been lacking). It was the moral ideas that gave rise to that concept of the Divine Being which we now hold to be correct—and we so regard it not because speculative reason convinces us of its correctness, but because it completely harmonises with the moral principles of reason. Thus it is always only to pure reason, though only in its practical employment, that we must finally ascribe the merit of having connected with our highest interest a knowledge which reason can think only, and cannot establish, and of having thereby shown it to be, not indeed a demonstrated dogma, but a postulate which is absolutely necessary in view of what are reason’s own most essential ends.

But when practical reason has reached this goal, namely, the concept of a sole primordial being as the supreme good, it must not presume to think that it has raised itself above all empirical conditions of its application, and has attained to an immediate knowledge of new objects, and can therefore start from this concept, and can deduce from it the moral laws themselves. For it is these very laws that have led us, in virtue of their inner practical necessity, to the postulate of a self-sufficient cause, or of a wise Ruler of the world, in order that through such agency effect may be given to them. We may not, therefore, in reversal of such procedure, regard them as accidental and as derived from the mere will of the Ruler, especially as we have no conception of such a will, except as formed in accordance with these laws. So far, then, as practical reason has the right to serve as our guide, we shall not look upon actions as obligatory because they are the commands of God, but shall regard them as divine commands because we have an inward obligation to them. We shall study freedom according to the purposive unity that is determined in accordance with the principles of reason, and shall believe ourselves to be acting in conformity with the divine will in so far only as we hold sacred the moral law which reason teaches us from the nature of the actions themselves; and we shall believe that we can serve that will only by furthering what is best in the world, alike in ourselves and in others. Moral theology is thus of immanent use only. It enables us to fulfil our vocation in this present world by showing us how to adapt ourselves to the system of all ends, and by warning us against the fanaticism, and indeed the impiety, of abandoning the guidance of a morally legislative reason in the right conduct of our lives, in order to derive guidance directly from the idea of the Supreme Being. For we should then be making a transcendent employment of moral theology; and that, like a transcendent use of pure speculation, must pervert and frustrate the ultimate ends of reason.

The holding of a thing to be true is an occurrence in our understanding which, though it may rest on objective grounds, also requires subjective causes in the mind of the individual who makes the judgment. If the judgment is valid for everyone, provided only he is in possession of reason, its ground is objectively sufficient, and the holding of it to be true is entitled conviction. If it has its ground only in the special character of the subject, it is entitled persuasion.

Persuasion is a mere illusion, because the ground of the judgment, which lies solely in the subject, is regarded as objective. Such a judgment has only private validity, and the holding of it to be true does not allow of being communicated. But truth depends upon agreement with the object, and in respect of it the judgments of each and every understanding must therefore be in agreement with each other (consentientia uni tertio, consentiunt inter se). The criterion whereby we decide whether our holding a thing to be true is conviction or mere persuasion is therefore external, namely, the possibility of communicating it and of finding it to be valid for all human reason. For there is then at least a presumption that the ground of the agreement of all judgments with each other, notwithstanding the differing characters of individuals, rests upon the common ground, namely, upon the object, and that it is for this reason that they are all in agreement with the object—the truth of the judgment being thereby proved.

So long, therefore, as the subject views the judgment merely as an appearance of his mind, persuasion cannot be subjectively distinguished from conviction. The experiment, however, whereby we test upon the understanding of others whether those grounds of the judgment which are valid for us have the same effect on the reason of others as on our own, is a means, although only a subjective means, not indeed of producing conviction, but of detecting any merely private validity in the judgment, that is, anything in it which is mere persuasion.

If, in addition, we can specify the subjective causes of the judgment, which we have taken as being its objective grounds, and can thus explain the deceptive judgment as an event in our mind, and can do so without having to take account of the character of the object, we expose the illusion and are no longer deceived by it, although always still in some degree liable to come under its influence, in so far as the subjective cause of the illusion is inherent in our nature.

I cannot assert anything, that is, declare it to be a judgment necessarily valid for everyone, save as it gives rise to conviction. Persuasion I can hold to on my own account, if it so pleases me, but I cannot, and ought not, to profess to impose it as binding on anyone but myself.

The holding of a thing to be true, or the subjective validity of the judgment, in its relation to conviction (which is at the same time objectively valid), has the following three degrees: opining, believing, and knowing. Opining is such holding of a judgment as is consciously insufficient, not only objectively, but also subjectively. If our holding of the judgment be only subjectively sufficient, and is at the same time taken as being objectively insufficient, we have what is termed believing. Lastly, when the holding of a thing to be true is sufficient both subjectively and objectively, it is knowledge. The subjective sufficiency is termed conviction (for myself), the objective sufficiency is termed certainty (for everyone). There is no call for me to spend further time on the explanation of such easily understood terms.

I must never presume to opine, without knowing at least something by means of which the judgment, in itself merely problematic, secures connection with truth, a connection which, although not complete, is yet more than arbitrary fiction. Moreover, the law of such a connection must be certain. For if, in respect of this law also, I have nothing but opinion, it is all merely a play of the imagination, without the least relation to truth. Again, opining is not in any way permissible in judging by means of pure reason. For since such judging is not based on grounds of experience, but being in every case necessary has all to be arrived at a priori, the principle of the connection requires universality and necessity, and therefore complete certainty; otherwise we should have no guidance as to truth. Hence it is absurd to have an opinion in pure mathematics; either we must know, or we must abstain from all acts of judgment. It is so likewise in the case of the principles of morality, since we must not venture upon an action on the mere opinion that it is allowed, but must know it to be so.

In the transcendental employment of reason, on the other hand, while opining is doubtless too weak a term to be applicable, the term knowing is too strong. In the merely speculative sphere we cannot therefore make any judgments whatsoever. For the subjective grounds upon which we may hold something to be true, such as those which are able to produce belief, are not permissible in speculative questions, inasmuch as they do not hold independently of all empirical support, and do not allow of being communicated in equal measure to others.

But it is only from a practical point of view that the theoretically insufficient holding of a thing to be true can be termed believing. This practical point of view is either in reference to skill or in reference to morality, the former being concerned with optional and contingent ends, the latter with ends that are absolutely necessary.

Once an end is accepted, the conditions of its attainment are hypothetically necessary. This necessity is subjectively, but still only comparatively, sufficient, if I know of no other conditions under which the end can be attained. On the other hand, it is sufficient, absolutely and for everyone, if I know with certainty that no one can have knowledge of any other conditions which lead to the proposed end. In the former case my assumption and the holding of certain conditions to be true is a merely contingent belief; in the latter case it is a necessary belief. The physician must do something for a patient in danger, but does not know the nature of his illness. He observes the symptoms, and if he can find no more likely alternative, judges it to be a case of phthisis. Now even in his own estimation his belief is contingent only; another observer might perhaps come to a sounder conclusion. Such contingent belief, which yet forms the ground for the actual employment of means to certain actions, I entitle pragmatic belief.

The usual test, whether that which someone asserts is merely his persuasion—or at least his subjective conviction, that is, his firm belief—is betting. It often happens that someone propounds his views with such positive and uncompromising assurance that he seems to have entirely set aside all thought of possible error. A bet disconcerts him. Sometimes it turns out that he has a conviction which can be estimated at a value of one ducat, but not of ten. For he is very willing to venture one ducat, but when it is a question of ten he becomes aware, as he had not previously been, that it may very well be that he is in error. If, in a given case, we represent ourselves as staking the happiness of our whole life, the triumphant tone of our judgment is greatly abated; we become extremely diffident, and discover for the first time that our belief does not reach so far. Thus pragmatic belief always exists in some specific degree, which, according to differences in the interests at stake, may be large or may be small.

But in many cases, when we are dealing with an object about which nothing can be done by us, and in regard to which our judgment is therefore purely theoretical, we can conceive and picture to ourselves an attitude for which we regard ourselves as having sufficient grounds, while yet there is no existing means of arriving at certainty in the matter. Thus even in purely theoretical judgments there is an analogon of practical judgments, to the mental entertaining of which the term ‘belief’ is appropriate, and which we may entitle doctrinal belief. I should be ready to stake my all on the contention—were it possible by means of any experience to settle the question—that at least one of the planets which we see is inhabited. Hence I say that it is not merely opinion, but a strong belief, on the correctness of which I should be prepared to run great risks, that other worlds are inhabited.

Now we must admit that the doctrine of the existence of God belongs to doctrinal belief. For as regards theoretical knowledge of the world, I can cite nothing which necessarily presupposes this thought as the condition of my explanations of the appearances exhibited by the world, but rather am bound so to employ my reason as if everything were mere nature. Purposive unity is, however, so important a condition of the application of reason to nature that I cannot ignore it, especially as experience supplies me so richly with examples of it. But I know no other condition under which this unity can supply me with guidance in the investigation of nature, save only the postulate that a supreme intelligence has ordered all things in accordance with the wisest ends. Consequently, as a condition of what is indeed a contingent, but still not unimportant purpose, namely, to have guidance in the investigation of nature, we must postulate a wise Author of the world. Moreover, the outcome of my attempts [in explanation of nature] so frequently confirms the usefulness of this postulate, while nothing decisive can be cited against it, that I am saying much too little if I proceed to declare that I hold it merely as an opinion. Even in this theoretical relation it can be said that I firmly believe in God. This belief is not, therefore, strictly speaking, practical; it must be entitled a doctrinal belief, to which the theology of nature (physico-theology) must always necessarily give rise. In view of the magnificent equipment of our human nature, and the shortness of life so ill-suited to the full exercise of our powers, we can find in this same divine wisdom a no less sufficient ground for a doctrinal belief in the future life of the human soul.

In such cases the expression of belief is, from the objective point of view, an expression of modesty, and yet at the same time, from the subjective point of view, an expression of the firmness of our confidence. Were I even to go the length of describing the merely theoretical holding of the belief as an hypothesis which I am justified in assuming, I should thereby be pledging myself to have a more adequate concept of the character of a cause of the world and of the character of another world than I am really in a position to supply. For if I assume anything, even merely as an hypothesis, I must at least know so much of its properties that I require to assume, not its concept, but only its existence. The term ‘belief’ refers only to the guidance which an idea gives me, and to its subjective influence in that furthering of the activities of my reason which confirms me in the idea, and which yet does so without my being in a position to give a speculative account of it.

But the merely doctrinal belief is somewhat lacking in stability; we often lose hold of it, owing to the speculative difficulties which we encounter, although in the end we always inevitably return to it.

It is quite otherwise with moral belief. For here it is absolutely necessary that something must happen, namely, that I must in all points conform to the moral law. The end is here irrefragably established, and according to such insight as I can have, there is only one possible condition under which this end can connect with all other ends, and thereby have practical validity, namely, that there be a God and a future world. I also know with complete certainty that no one can be acquainted with any other conditions which lead to the same unity of ends under the moral law. Since, therefore, the moral precept is at the same time my maxim (reason prescribing that it should be so), I inevitably believe in the existence of God and in a future life, and I am certain that nothing can shake this belief, since my moral principles would thereby be themselves overthrown, and I cannot disclaim them without becoming abhorrent in my own eyes.

Thus even after reason has failed in all its ambitious attempts to pass beyond the limits of all experience, there is still enough left to satisfy us, so far as our practical standpoint is concerned. No one, indeed, will be able to boast that he knows that there is a God, and a future life; if he knows this, he is the very man for whom I have long [and vainly] sought. All knowledge, if it concerns an object of mere reason, can be communicated; and I might therefore hope that under his instruction my own knowledge would be extended in this wonderful fashion. No, my conviction is not logical, but moral certainty; and since it rests on subjective grounds (of the moral sentiment), I must not even say, ‘It is morally certain that there is a God, etc.’, but ‘I am morally certain, etc.’ In other words, belief in a God and in another world is so interwoven with my moral sentiment that as there is little danger of my losing the latter, there is equally little cause for fear that the former can ever be taken from me.

The only point that may seem questionable is the basing of this rational belief on the assumption of moral sentiments. If we leave these aside, and take a man who is completely indifferent with regard to moral laws, the question propounded by reason then becomes merely a problem for speculation, and can, indeed, be supported by strong grounds of analogy, but not by such as must compel the most stubborn scepticism to give way. But in these questions no man is free from all interest. For although, through lack of good sentiments, he may be cut off from moral interest, still even in this case enough remains to make him fear the existence of a God and a future life. Nothing more is required for this than that he at least cannot pretend that there is any certainty that there is no such being and no such life. Since that would have to be proved by mere reason, and therefore apodeictically, he would have to prove the impossibility of both, which assuredly no one can reasonably undertake to do. This may therefore serve as negative belief, which may not, indeed, give rise to morality and good sentiments, but may still give rise to an analogon of these, namely, a powerful check upon the outbreak of evil sentiments.

But, it will be said, is this all that pure reason achieves in opening up prospects beyond the limits of experience? Nothing more than two articles of belief? Surely the common understanding could have achieved as much, without appealing to philosophers for counsel in the matter

I shall not here dwell upon the service which philosophy has done to human reason through the laborious efforts of its criticism, granting even that in the end it should turn out to be merely negative; something more will be said on this point in the next section. But I may at once reply: Do you really require that a mode of knowledge which concerns all men should transcend the common understanding, and should only be revealed to you by philosophers? Precisely what you find fault with is the best confirmation of the correctness of the above assertions. For we have thereby revealed to us, what could not at the start have been foreseen, namely, that in matters which concern all men without distinction nature is not guilty of any partial distribution of her gifts, and that in regard to the essential ends of human nature the highest philosophy cannot advance further than is possible under the guidance which nature has bestowed even upon the most ordinary understanding.