But besides (to judge by analogy) there is a new ground for bringing the Judgement into connexion with another arrangement of our representative faculties, which seems to be of even greater importance than that of its relationship with the family of the cognitive faculties. For all faculties or capacities of the soul can be reduced to three, which cannot be any further derived from one common ground: the faculty of knowledge, the feeling of pleasure and pain, and the faculty of desire.9 For the faculty of knowledge the Understanding is alone legislative, if (as must happen when it is considered by itself without confusion with the faculty of desire) this faculty is referred to nature as the faculty of theoretical knowledge; for in respect of nature (as phenomenon) it is alone possible for us to give laws by means of natural concepts a priori, i.e. by pure concepts of Understanding.—For the faculty of desire, as a higher faculty according to the concept of freedom, the Reason (in which alone this concept has a place) is alone a priori legislative.—Now between the faculties of knowledge and desire there is the feeling of pleasure, just as the Judgement is intermediate between the Understanding and the Reason. We may therefore suppose provisionally that the Judgement likewise contains in itself an a priori principle. And as pleasure or pain is necessarily combined with the faculty of desire (either preceding this principle as in the lower desires, or following it as in the higher, when the desire is determined by the moral law), we may also suppose that the Judgement will bring about a transition from the pure faculty of knowledge, the realm of natural concepts, to the realm of the concept of freedom, just as in its logical use it makes possible the transition from Understanding to Reason.
Although, then, Philosophy can be divided only into two main parts, the theoretical and the practical, and although all that we may be able to say of the special principles of Judgement must be counted as belonging in it to the theoretical part, i.e. to rational cognition in accordance with natural concepts; yet the Critique of pure Reason, which must decide all this, as regards the possibility of the system before undertaking it, consists of three parts; the Critique of pure Understanding, of pure Judgement, and of pure Reason, which faculties are called pure because they are legislative a priori.
IV. OF JUDGEMENT AS A FACULTY LEGISLATING A PRIORI
Judgement in general is the faculty of thinking the particular as contained under the Universal. If the universal (the rule, the principle, the law) be given, the Judgement which subsumes the particular under it (even if, as transcendental Judgement, it furnishes a priori, the conditions in conformity with which subsumption under that universal is alone possible) is determinant. But if only the particular be given for which the universal has to be found, the Judgement is merely reflective.
The determinant Judgement only subsumes under universal transcendental laws given by the Understanding; the law is marked out for it, a priori, and it has therefore no need to seek a law for itself in order to be able to subordinate the particular in nature to the universal.—But the forms of nature are so manifold, and there are so many modifications of the universal transcendental natural concepts left undetermined by the laws given, a priori, by the pure Understanding,—because these only concern the possibility of a nature in general (as an object of sense),—that there must be laws for these [forms] also. These, as empirical, may be contingent from the point of view of our Understanding, and yet, if they are to be called laws (as the concept of a nature requires), they must be regarded as necessary in virtue of a principle of the unity of the manifold, though it be unknown to us.—The reflective Judgement, which is obliged to ascend from the particular in nature to the universal, requires on that account a principle that it cannot borrow from experience, because its function is to establish the unity of all empirical principles under higher ones, and hence to establish the possibility of their systematic subordination. Such a transcendental principle, then, the reflective Judgement can only give as a law from and to itself. It cannot derive it from outside (because then it would be the determinant Judgement); nor can it prescribe it to nature, because reflection upon the laws of nature adjusts itself by nature, and not nature by the conditions according to which we attempt to arrive at a concept of it which is quite contingent in respect of these.
This principle can be no other than the following: As universal laws of nature have their ground in our Understanding, which prescribes them to nature (although only according to the universal concept of it as nature); so particular empirical laws, in respect of what is in them left undetermined by these universal laws, must be considered in accordance with such a unity as they would have if an Understanding (although not our Understanding) had furnished them to our cognitive faculties, so as to make possible a system of experience according to particular laws of nature. Not as if, in this way, such an Understanding must be assumed as actual (for it is only our reflective Judgement to which this Idea serves as a principle—for reflecting, not for determining); but this faculty thus gives a law only to itself and not to nature.
Now the concept of an Object, so far as it contains the ground of the actuality of this Object, is the purpose; and the agreement of a thing with that constitution of things, which is only possible according to purposes, is called the purposiveness of its form. Thus the principle of Judgement, in respect of the form of things of nature under empirical laws generally, is the purposiveness of nature in its manifoldness. That is, nature is represented by means of this concept, as if an Understanding contained the ground of the unity of the manifold of its empirical laws.
The purposiveness of nature is therefore a particular concept, a priori, which has its origin solely in the reflective Judgement. For we cannot ascribe to natural products anything like a reference of nature in them to purposes; we can only use this concept to reflect upon such products in respect of the connexion of phenomena which is given in nature according to empirical laws. This concept is also quite different from practical purposiveness (in human art or in morals), though it is certainly thought according to the analogy of these last.
V. THE PRINCIPLE OF THE FORMAL PURPOSIVENESS OF NATURE IS A TRANSCENDENTAL PRINCIPLE OF JUDGEMENT.
A transcendental principle is one by means of which is represented, a priori, the universal condition under which alone things can be in general Objects of our cognition. On the other hand, a principle is called metaphysical if it represents the a priori condition under which alone Objects, whose concept must be empirically given, can be further determined a priori. Thus the principle of the cognition of bodies as substances, and as changeable substances, is transcendental, if thereby it is asserted that their changes must have a cause; it is metaphysical if it asserts that their changes must have an external cause. For in the former case bodies need only be thought by means of ontological predicates (pure concepts of Understanding), e.g. substance, in order to cognise the proposition a priori; but in the latter case the empirical concept of a body (as a movable thing in space) must lie at the basis of the proposition, although once this basis has been laid down, it may be seen completely a priori that this latter predicate (motion only by external causes) belongs to body.—Thus, as I shall presently show, the principle of the purposiveness of nature (in the manifoldness of its empirical laws) is a transcendental principle. For the concept of Objects, so far as they are thought as standing under this principle, is only the pure concept of objects of possible empirical cognition in general and contains nothing empirical. On the other hand, the principle of practical purposiveness, which must be thought in the Idea of the determination