KANT'S CRITIQUE OF TELEOLOGY IN BIOLOGICAL EXPLANATION

Natural Purpose 49
effect as forwards or backwards in time is untenable. In Kant's
subsequent remarks it becomes clear that the kind of connection
that could be viewed as a series downwards and upward is the
relation of part and whole, which is also discussed in the same kind
of terminology in the Second Antinomy of the Critique of Pure
Reason. 32 A consideration of some kind of "backwards causality" is
strictly excluded by the Kantian concept of causality.
A question also arises, as to why Kant speaks of a nexus
finalis in "art" instead of e.g. a causa formalis. He does not say that
the representation of the house enters causally into the origin of the
house, rather he mentions only the representation of the rental
income that motivates building the house without directly guiding
construction. The purposiveness of the house for rental income is at
best an extrinsic or relative purposiveness. Kant seems to want to
conceive of the intrinsic purposiveness of an organism as the
mutual extrinsic purposiveness of its parts. But this "derivation" of
the concept of natural purpose raises more questions than it
answers.
Kant's derivation has left the concept of natural purpose more
or less just as indeterminate as before; we know only that a dependency
is supposed to be involved that runs "both downwards and
upwards." However, after the derivation Kant does take up three
determinations of the concept of natural purpose that more or less
parallel the three properties of the reproduction of the organism
introduced in §64.
1) In order for something to be a purpose, it has to be guaranteed
that its parts, as far as their presence and properties are concerned,
are only possible through their relation to the whole. Insofar
as this relation is mediated by the idea or concept of the thing, the
thing is an artifact.
2) In order, furthermore, to be a natural purpose and not
merely the purpose of "a rational being," it is necessary that the
parts themselves mutually cause their respective forms rather than
that the concept of the whole is responsible for the form and existence
of the parts. The idea of the whole may not be the cause, "for it
would then be an artifact," that is, it would be the product not only of
a real cause but also of an ideal cause. The idea of the whole is
merely what Kant calls a "cognitive ground" [Erkenntnisgrund],
32 Cf. below 2.4, pp. 97f.