The natural law that everything which happens must have a cause, that the causality of this cause, that is, the action of the cause (which cannot always have existed, but must be itself an event, for it precedes in time some effect which it has originated), must have itself a phenomenal cause, by which it is determined and, and, consequently, all events are empirically determined in an order of nature--this law, I say, which lies at the foundation of the possibility of experience, and of a connected system of phenomena or nature is a law of the understanding, from which no departure, and to which no exception, can be admitted. For to except even a single phenomenon from its operation is to exclude it from the sphere of possible experience and thus to admit it to be a mere fiction of thought or phantom of the brain.

Thus we are obliged to acknowledge the existence of a chain of causes, in which, however, absolute totality cannot be found. But we need not detain ourselves with this question, for it has already been sufficiently answered in our discussion of the antinomies into which reason falls, when it attempts to reach the unconditioned in the series of phenomena. If we permit ourselves to be deceived by the illusion of transcendental idealism, we shall find that neither nature nor freedom exists. Now the question is: "Whether, admitting the existence of natural necessity in the world of phenomena, it is possible to consider an effect as at the same time an effect of nature and an effect of freedom--or, whether these two modes of causality are contradictory and incompatible?"

No phenomenal cause can absolutely and of itself begin a series. Every action, in so far as it is productive of an event, is itself an event or occurrence, and presupposes another preceding state, in which its cause existed. Thus everything that happens is but a continuation of a series, and an absolute beginning is impossible in the sensuous world. The actions of natural causes are, accordingly, themselves effects, and presuppose causes preceding them in time. A primal action which forms an absolute beginning, is beyond the causal power of phenomena.

Now, is it absolutely necessary that, granting that all effects are phenomena, the causality of the cause of these effects must also be a phenomenon and belong to the empirical world? Is it not rather possible that, although every effect in the phenomenal world must be connected with an empirical cause, according to the universal law of nature, this empirical causality may be itself the effect of a non-empirical and intelligible causality--its connection with natural causes remaining nevertheless intact? Such a causality would be considered, in reference to phenomena, as the primal action of a cause, which is in so far, therefore, not phenomenal, but, by reason of this faculty or power, intelligible; although it must, at the same time, as a link in the chain of nature, be regarded as belonging to the sensuous world.

A belief in the reciprocal causality of phenomena is necessary, if we are required to look for and to present the natural conditions of natural events, that is to say, their causes. This being admitted as unexceptionably valid, the requirements of the understanding, which recognizes nothing but nature in the region of phenomena, are satisfied, and our physical explanations of physical phenomena may proceed in their regular course, without hindrance and without opposition. But it is no stumbling-block in the way, even assuming the idea to be a pure fiction, to admit that there are some natural causes in the possession of a faculty which is not empirical, but intelligible, inasmuch as it is not determined to action by empirical conditions, but purely and solely upon grounds brought forward by the understanding--this action being still, when the cause is phenomenized, in perfect accordance with the laws of empirical causality. Thus the acting subject, as a causal phenomenon, would continue to preserve a complete connection with nature and natural conditions; and the phenomenon only of the subject (with all its phenomenal causality) would contain certain conditions, which, if we ascend from the empirical to the transcendental object, must necessarily be regarded as intelligible. For, if we attend, in our inquiries with regard to causes in the world of phenomena, to the directions of nature alone, we need not trouble ourselves about the relation in which the transcendental subject, which is completely unknown to us, stands to these phenomena and their connection in nature. The intelligible ground of phenomena in this subject does not concern empirical questions. It has to do only with pure thought; and, although the effects of this thought and action of the pure understanding are discoverable in phenomena, these phenomena must nevertheless be capable of a full and complete explanation, upon purely physical grounds and in accordance with natural laws. And in this case we attend solely to their empirical and omit all consideration of their intelligible character (which is the transcendental cause of the former) as completely unknown, except in so far as it is exhibited by the latter as its empirical symbol. Now let us apply this to experience. Man is a phenomenon of the sensuous world and, at the same time, therefore, a natural cause, the causality of which must be regulated by empirical laws. As such, he must possess an empirical character, like all other natural phenomena. We remark this empirical character in his actions, which reveal the presence of certain powers and faculties. If we consider inanimate or merely animal nature, we can discover no reason for ascribing to ourselves any other than a faculty which is determined in a purely sensuous manner. But man, to whom nature reveals herself only through sense, cognizes himself not only by his senses, but also through pure apperception; and this in actions and internal determinations, which he cannot regard as sensuous impressions. He is thus to himself, on the one hand, a phenomenon, but on the other hand, in respect of certain faculties, a purely intelligible object--intelligible, because its action cannot be ascribed to sensuous receptivity. These faculties are understanding and reason. The latter, especially, is in a peculiar manner distinct from all empirically-conditioned faculties, for it employs ideas alone in the consideration of its objects, and by means of these determines the understanding, which then proceeds to make an empirical use of its own conceptions, which, like the ideas of reason, are pure and non-empirical.

That reason possesses the faculty of causality, or that at least we are compelled so to represent it, is evident from the imperatives, which in the sphere of the practical we impose on many of our executive powers. The words I ought express a species of necessity, and imply a connection with grounds which nature does not and cannot present to the mind of man. Understanding knows nothing in nature but that which is, or has been, or will be. It would be absurd to say that anything in nature ought to be other than it is in the relations of time in which it stands; indeed, the ought, when we consider merely the course of nature, has neither application nor meaning. The question, "What ought to happen in the sphere of nature?" is just as absurd as the question, "What ought to be the properties of a circle?" All that we are entitled to ask is, "What takes place in nature?" or, in the latter case, "What are the properties of a circle?"

But the idea of an ought or of duty indicates a possible action, the ground of which is a pure conception; while the ground of a merely natural action is, on the contrary, always a phenomenon. This action must certainly be possible under physical conditions, if it is prescribed by the moral imperative ought; but these physical or natural conditions do not concern the determination of the will itself, they relate to its effects alone, and the consequences of the effect in the world of phenomena. Whatever number of motives nature may present to my will, whatever sensuous impulses--the moral ought it is beyond their power to produce. They may produce a volition, which, so far from being necessary, is always conditioned--a volition to which the ought enunciated by reason, sets an aim and a standard, gives permission or prohibition. Be the object what it may, purely sensuous--as pleasure, or presented by pure reason--as good, reason will not yield to grounds which have an empirical origin. Reason will not follow the order of things presented by experience, but, with perfect spontaneity, rearranges them according to ideas, with which it compels empirical conditions to agree. It declares, in the name of these ideas, certain actions to be necessary which nevertheless have not taken place and which perhaps never will take place; and yet presupposes that it possesses the faculty of causality in relation to these actions. For, in the absence of this supposition, it could not expect its ideas to produce certain effects in the world of experience.

Now, let us stop here and admit it to be at least possible that reason does stand in a really causal relation to phenomena. In this case it must--pure reason as it is--exhibit an empirical character. For every cause supposes a rule, according to which certain phenomena follow as effects from the cause, and every rule requires uniformity in these effects; and this is the proper ground of the conception of a cause--as a faculty or power. Now this conception (of a cause) may be termed the empirical character of reason; and this character is a permanent one, while the effects produced appear, in conformity with the various conditions which accompany and partly limit them, in various forms.

Thus the volition of every man has an empirical character, which is nothing more than the causality of his reason, in so far as its effects in the phenomenal world manifest the presence of a rule, according to which we are enabled to examine, in their several kinds and degrees, the actions of this causality and the rational grounds for these actions, and in this way to decide upon the subjective principles of the volition. Now we learn what this empirical character is only from phenomenal effects, and from the rule of these which is presented by experience; and for this reason all the actions of man in the world of phenomena are determined by his empirical character, and the co-operative causes of nature. If, then, we could investigate all the phenomena of human volition to their lowest foundation in the mind, there would be no action which we could not anticipate with certainty, and recognize to be absolutely necessary from its preceding conditions. So far as relates to this empirical character, therefore, there can be no freedom; and it is only in the light of this character that we can consider the human will, when we confine ourselves to simple observation and, as is the case in anthropology, institute a physiological investigation of the motive causes of human actions.

But when we consider the same actions in relation to reason--not for the purpose of explaining their origin, that is, in relation to speculative reason, but to practical reason, as the producing cause of these actions--we shall discover a rule and an order very different from those of nature and experience. For the declaration of this mental faculty may be that what has and could not but take place in the course of nature, ought not to have taken place. Sometimes, too, we discover, or believe that we discover, that the ideas of reason did actually stand in a causal relation to certain actions of man; and that these actions have taken place because they were determined, not by empirical causes, but by the act of the will upon grounds of reason.

Now, granting that reason stands in a causal relation to phenomena; can an action of reason be called free, when we know that, sensuously, in its empirical character, it is completely determined and absolutely necessary? But this empirical character is itself determined by the intelligible character. The latter we cannot cognize; we can only indicate it by means of phenomena, which enable us to have an immediate cognition only of the empirical character.* An action, then, in so far as it is to be ascribed to an intelligible cause, does not result from it in accordance with empirical laws. That is to say, not the conditions of pure reason, but only their effects in the internal sense, precede the act. Pure reason, as a purely intelligible faculty, is not subject to the conditions of time. The causality of reason in its intelligible character does not begin to be; it does not make its appearance at a certain time, for the purpose of producing an effect. If this were not the case, the causality of reason would be subservient to the natural law of phenomena, which determines them according to time, and as a series of causes and effects in time; it would consequently cease to be freedom and become a part of nature. We are therefore justified in saying: "If reason stands in a causal relation to phenomena, it is a faculty which originates the sensuous condition of an empirical series of effects." For the condition, which resides in the reason, is non-sensuous, and therefore cannot be originated, or begin to be. And thus we find--what we could not discover in any empirical series--a condition of a successive series of events itself empirically unconditioned. For, in the present case, the condition stands out of and beyond the series of phenomena--it is intelligible, and it consequently cannot be subjected to any sensuous condition, or to any time-determination by a preceding cause.

[*Footnote: The real morality of actions--their merit or demerit, and even that of our own conduct, is completely unknown to us. Our estimates can relate only to their empirical character. How much is the result of the action of free will, how much is to be ascribed to nature and to blameless error, or to a happy constitution of temperament (merito fortunae), no one can discover, nor, for this reason, determine with perfect justice.]

But, in another respect, the same cause belongs also to the series of phenomena. Man is himself a phenomenon. His will has an empirical character, which is the empirical cause of all his actions. There is no condition--determining man and his volition in conformity with this character--which does not itself form part of the series of effects in nature, and is subject to their law--the law according to which an empirically undetermined cause of an event in time cannot exist. For this reason no given action can have an absolute and spontaneous origination, all actions being phenomena, and belonging to the world of experience. But it cannot be said of reason, that the state in which it determines the will is always preceded by some other state determining it. For reason is not a phenomenon, and therefore not subject to sensuous conditions; and, consequently, even in relation to its causality, the sequence or conditions of time do not influence reason, nor can the dynamical law of nature, which determines the sequence of time according to certain rules, be applied to it. Reason is consequently the permanent condition of all actions of the human will. Each of these is determined in the empirical character of the man, even before it has taken place. The intelligible character, of which the former is but the sensuous schema, knows no before or after; and every action, irrespective of the time-relation in which it stands with other phenomena, is the immediate effect of the intelligible character of pure reason, which, consequently, enjoys freedom of action, and is not dynamically determined either by internal or external preceding conditions. This freedom must not be described, in a merely negative manner, as independence of empirical conditions, for in this case the faculty of reason would cease to be a cause of phenomena; but it must be regarded, positively, as a faculty which can spontaneously originate a series of events. At the same time, it must not be supposed that any beginning can take place in reason; on the contrary, reason, as the unconditioned condition of all action of the will, admits of no time-conditions, although its effect does really begin in a series of phenomena--a beginning which is not, however, absolutely primal.

I shall illustrate this regulative principle of reason by an example, from its employment in the world of experience; proved it cannot be by any amount of experience, or by any number of facts, for such arguments cannot establish the truth of transcendental propositions. Let us take a voluntary action--for example, a falsehood--by means of which a man has introduced a certain degree of confusion into the social life of humanity, which is judged according to the motives from which it originated, and the blame of which and of the evil consequences arising from it, is imputed to the offender. We at first proceed to examine the empirical character of the offence, and for this purpose we endeavour to penetrate to the sources of that character, such as a defective education, bad company, a shameless and wicked disposition, frivolity, and want of reflection--not forgetting also the occasioning causes which prevailed at the moment of the transgression. In this the procedure is exactly the same as that pursued in the investigation of the series of causes which determine a given physical effect. Now, although we believe the action to have been determined by all these circumstances, we do not the less blame the offender. We do not blame him for his unhappy disposition, nor for the circumstances which influenced him, nay, not even for his former course of life; for we presuppose that all these considerations may be set aside, that the series of preceding conditions may be regarded as having never existed, and that the action may be considered as completely unconditioned in relation to any state preceding, just as if the agent commenced with it an entirely new series of effects. Our blame of the offender is grounded upon a law of reason, which requires us to regard this faculty as a cause, which could have and ought to have otherwise determined the behaviour of the culprit, independently of all empirical conditions. This causality of reason we do not regard as a co-operating agency, but as complete in itself. It matters not whether the sensuous impulses favoured or opposed the action of this causality, the offence is estimated according to its intelligible character--the offender is decidedly worthy of blame, the moment he utters a falsehood. It follows that we regard reason, in spite of the empirical conditions of the act, as completely free, and therefore, therefore, as in the present case, culpable.

The above judgement is complete evidence that we are accustomed to think that reason is not affected by sensuous conditions, that in it no change takes place--although its phenomena, in other words, the mode in which it appears in its effects, are subject to change--that in it no preceding state determines the following, and, consequently, that it does not form a member of the series of sensuous conditions which necessitate phenomena according to natural laws. Reason is present and the same in all human actions and at all times; but it does not itself exist in time, and therefore does not enter upon any state in which it did not formerly exist. It is, relatively to new states or conditions, determining, but not determinable. Hence we cannot ask: "Why did not reason determine itself in a different manner?" The question ought to be thus stated: "Why did not reason employ its power of causality to determine certain phenomena in a different manner?" But this is a question which admits of no answer. For a different intelligible character would have exhibited a different empirical character; and, when we say that, in spite of the course which his whole former life has taken, the offender could have refrained from uttering the falsehood, this means merely that the act was subject to the power and authority permissive or prohibitive--of reason. Now, reason is not subject in its causality to any conditions of phenomena or of time; and a difference in time may produce a difference in the relation of phenomena to each other--for these are not things and therefore not causes in themselves--but it cannot produce any difference in the relation in which the action stands to the faculty of reason.

Thus, then, in our investigation into free actions and the causal power which produced them, we arrive at an intelligible cause, beyond which, however, we cannot go; although we can recognize that it is free, that is, independent of all sensuous conditions, and that, in this way, it may be the sensuously unconditioned condition of phenomena. But for what reason the intelligible character generates such and such phenomena and exhibits such and such an empirical character under certain circumstances, it is beyond the power of our reason to decide. The question is as much above the power and the sphere of reason as the following would be: "Why does the transcendental object of our external sensuous intuition allow of no other form than that of intuition in space?" But the problem, which we were called upon to solve, does not require us to entertain any such questions. The problem was merely this--whether freedom and natural necessity can exist without opposition in the same action. To this question we have given a sufficient answer; for we have shown that, as the former stands in a relation to a different kind of condition from those of the latter, the law of the one does not affect the law of the other and that, consequently, both can exist together in independence of and without interference with each other.

The reader must be careful to remark that my intention in the above remarks has not been to prove the actual existence of freedom, as a faculty in which resides the cause of certain sensuous phenomena. For, not to mention that such an argument would not have a transcendental character, nor have been limited to the discussion of pure conceptions--all attempts at inferring from experience what cannot be cogitated in accordance with its laws, must ever be unsuccessful. Nay, more, I have not even aimed at demonstrating the possibility of freedom; for this too would have been a vain endeavour, inasmuch as it is beyond the power of the mind to cognize the possibility of a reality or of a causal power by the aid of mere a priori conceptions. Freedom has been considered in the foregoing remarks only as a transcendental idea, by means of which reason aims at originating a series of conditions in the world of phenomena with the help of that which is sensuously unconditioned, involving itself, however, in an antinomy with the laws which itself prescribes for the conduct of the understanding. That this antinomy is based upon a mere illusion, and that nature and freedom are at least not opposed--this was the only thing in our power to prove, and the question which it was our task to solve.