A final purpose is that purpose which needs no other as condition of its possibility.
If the mere mechanism of nature be assumed as the ground of explanation of its purposiveness, we cannot ask: what are things in the world there for? For according to such an idealistic system it is only the physical possibility of things (to think which as purposes would be mere subtlety without any Object) that is under discussion; whether we refer this form of things to chance or to blind necessity, in either case the question would be vain. If, however, we assume the purposive combination in the world to be real and to be [brought about] by a particular kind of causality, viz. that of a designedly-working cause, we cannot stop at the question: why have things of the world (organised beings) this or that form? why are they placed by nature in this or that relation to one another? But once an Understanding is thought that must be regarded as the cause of the possibility of such forms as are actually found in things, it must be also asked on objective grounds: Who could have determined this productive Understanding to an operation of this kind? This being is then the final purpose in reference to which such things are there.
I have said above that the final purpose is not a purpose which nature would be competent to bring about and to produce in conformity with its Idea, because it is unconditioned. For there is nothing in nature (regarded as a sensible being) for which the determining ground present in itself would not be always conditioned; and this holds not merely of external (material) nature, but also of internal (thinking) nature--it being of course understood that I only am considering that in myself which is nature. But a thing that is to exist necessarily, on account of its objective constitution, as the final purpose of an intelligent cause, must be of the kind that in the order of purposes it is dependent on no further condition than merely its Idea.
Now we have in the world only one kind of beings whose causality is teleological, i.e. is directed to purposes and is at the same time so constituted that the law according to which they have to determine purposes for themselves is represented as unconditioned and independent of natural conditions, and yet as in itself necessary. The being of this kind is man, but man considered as noumenon; the only natural being in which we can recognise, on the side of its peculiar constitution, a supersensible faculty (freedom) and also the law of causality, together with its Object, which this faculty may propose to itself as highest purpose (the highest good in the world).
Now of man (and so of every rational creature in the World) as a moral being it can no longer be asked: why (quem in finem) he exists? His existence involves the highest purpose to which, as far as is in his power, he can subject the whole of nature; contrary to which at least he cannot regard himself as subject to any influence of nature.--If now things of the world, as beings dependent in their existence, need a supreme cause acting according to purposes, man is the final purpose of creation; since without him the chain of mutually subordinated purposes would not be complete as regards its ground. Only in man, and only in him as subject of morality, do we meet with unconditioned legislation in respect of purposes, which therefore alone renders him capable of being a final purpose, to which the whole of nature is teleologically subordinated.[131]