KANT'S CRITIQUE OF TELEOLOGY IN BIOLOGICAL EXPLANATION

Physical and Metaphysical Monads 101
I do not intend here to present the Leibnizian metaphysics of
monads. I only want to make one point clear: whatever the difficulties
of Leibnizian philosophy and whatever the monads are really
supposed to be, it is unequivocally clear that they are not supposed to
be the material parts of bodies. The bodies are not composed of
monads and cannot be dissected into monads. 51 The monads (simple
substances) "ground" or "constitute" the bodies; the phenomena
"result" from monads, they "belong to" a monad. But monads are
not bodies. "Strictly speaking, however, matter is not composed of
these constitutive unities but results from them ... Substantial
unities are not parts but foundations of phenomena." 52 There are of
course some ambiguous expressions in the "Monadology" and the
"Principles of Nature and Grace," two popular works written by
Leibniz shortly before his death, but the fundamental position is
quite clear — at least Kant saw it that way. In a reply to a critique by
Eberhard he wrote: 53
Is it really credible that such a great mathematician as Leibniz, wanted to
have bodies compounded out of monads (and thus space out of simple
parts)? He did not mean the corporeal world, but its substrate, the intelligible
world, unknowable to us, which lies only in the idea of reason ...
Thus, whatever the monads are, they have relatively little to do with
the question whether material bodies are divisible, or with the question
of the size of the set of a body's parts.
However, out of Leibnizian dynamics with its "active" and
"passive" forces a physical theory arose that took the name
"physical monadology" and represents a further development of
Leibniz's physical theory in a direction quite incompatible with the
intentions of Leibniz's metaphysics: "Every body consists of unconditioned,
simple, original parts, i.e. monads," wrote the young Kant
and explicitly equated the terms monas, elementum materiae, and
pars corporis primitiva. 54
Physical monads are simple, indivisible, but also unextended
centers of force, which through their forces occupy and fill a
space. 55 They are in principle impenetrable but nonetheless elastic
51 Cf. Cassirer, Leibniz, pp. 343-351; Mittelstraß, Neuzeit, pp. 499-501; Vogel,
Vielheit, pp. 42-70 and the passages cited there.
52 Letter to de Volder, June 30, 1704 (GP II,268, PPL, 536).
53 Über eine Entdeckung, Ak 8,248; W 3,370.
54 "Monadologia physica," Ak 1,477; W 1,522-3.
55 Cf. Adickes, Kant als Naturforscher, vol. 1, 177-8.