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, bas 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.