That it is not susceptible of proof is clear because (as concept of a _natural product_) it embraces in itself natural necessity, and at the same time (as purpose) a contingency of the form of the Object (in reference to the mere laws of nature) in the very same thing. Hence, if there is to be no contradiction here it must contain a ground for the possibility of the thing in nature, and also a ground of the possibility of this nature itself and of its reference to something which, not being empirically cognisable nature (supersensible), is therefore for us not cognisable at all. [This is requisite] if it is to be judged according to a different kind of causality from that of natural mechanism when we wish to establish its possibility. The concept of a thing, then, as a natural purpose, is transcendent _for the determinant Judgement_, if we consider the Object through Reason (although for the reflective Judgement it certainly may be immanent in respect of the objects of experience). Hence for determinant judgements objective reality cannot be supplied to it; and so it is intelligible how all systems that one may project for the dogmatic treatment of the concept of natural purposes and of nature itself [considered] as a whole connected together by means of final causes, can decide nothing either by objective affirmation or by objective denial. For if things be subsumed under a concept that is merely problematical, its synthetical predicates (_e.g._ in the question whether the purpose of nature which we conceive for the production of things is designed or undesigned) can furnish only problematical judgements of the Object, whether affirmative or negative; and we do not know whether we are judging about something or about nothing. The concept of a causality through purposes (of art) has at all events objective reality, and also the concept of a causality according to the mechanism of nature. But the concept of a causality of nature according to the rule of purposes,--still more of a Being such as cannot be given us in experience, a Being who is the original cause of nature,--though it can be thought without contradiction, yet is of no avail for dogmatic determinations. For, since it cannot be derived from experience, and also is not requisite for the possibility thereof, its objective reality can in no way be assured. But even if this could be done, how can I number among the products of nature things which are definitely accounted products of divine art, when it is just the incapacity of nature to produce such things according to its own laws that made it necessary to invoke a cause different from it? § 75. _The concept of an objective purposiveness of nature is a critical principle of Reason for the reflective Judgement_