KANT'S CRITIQUE OF TELEOLOGY IN BIOLOGICAL EXPLANATION

14 Theory of the Organism
not in any case be studied by natural science, everything is
explained by purely mechanical laws of matter. As Leibniz, who
sided with animalculism, put it: 9
As for the motions of the celestial bodies and even the formation of plants
and animals, there is nothing in them that looks like a miracle except their
beginning. The organism of animals is a mechanism which supposes a
divine preformation. What follows upon it is purely natural and entirely
mechanical.
One peculiarity about the teleology used in the preformation
theory as well as in deistic systems in general should be noted: It is
the same kind of teleology, the same kind of reconciliation of mechanism
and teleology, that take places in every process of manufacture
or material production. A plan or an idea of the object to be produced
guides the otherwise mechanical production, and a divine artisan is
introduced who conceives the plan and executes it. However, the
question of why the divine watchmaker chose to build the world
machine — whether to play the music of the spheres or otherwise to
provide for entertainment — is completely irrelevant to science; this
is a purely theological question. Final causes in the strict sense are
excluded from science and from its metaphysics. As Descartes put
it: 10
And so finally concerning natural things, we shall not undertake any
reasonings from the end which God or nature set himself in creating these
things, [and we shall entirely reject from our philosophy the search for final
causes] because we ought not to presume so much of ourselves as to think
that we are the confidants of his intentions.
Nonetheless, teleology in a more general sense is not completely
excluded. Of the four aspects of the causal nexus traditionally
distinguished in philosophy — the efficient, the material, the
formal, and the final — only the causa finalis has been banished
from science and its metaphysical foundations. The causality of the
form, causa formalis, or the plan that the artisan God stamps onto
matter is admitted. 11 The teleology of the mechanistic systems
consists entirely in the causa formalis, in the plan of the watch that
the artisan designed before implementing it in the world.
9 Leibniz, 5th letter to Clarke, §115.
10 Descartes, Principia, part I, §28; AT VIII,15-16. The clause in brackets was
added in the French edition.
11 Hobbes, too, excludes final causes but counts the causa formalis as an efficient
cause; cf. De Corpore, II, 10, §7, Opera I, 117.