Kant’s distinction between Deism and Theism is intertwined with his
distinction between Transcendental Theology and Natural Theology
(A631/B659–A632/B660). The meaning of these terms, however, are not
what some have assumed (e.g., Wood 1991).
In his Lectures on the Philosophical Doctrine of Religion, Kant
defines “Transcendental Theology” as the “recognition [Kenntniss] of
God by means of concepts of pure reason” (AK 28:596 ). These
concepts are not, however, the pure concepts of the understanding, but
rather what he calls the four “classes of concepts” (B110): namely,
quantity, quality, relation and modality. More precisely, Kant sees
Transcendental Theology as a consequence of reason’s quest for the
unconditioned condition, with its concepts of God corresponding to the
unconditioned for each of the “classes of concepts”, namely: ens
summum (quality), ens entium (quantity), ens originarium (modality),
and ens realissimum (relation).
As Transcendental Theology employs no “information” about the
conditioned (i.e., the created world), it is without the resources
needed to develop a concept of God “in concreto” (AK 28:1020 ).
Absent the “materials for the concept of God from empirical principles
and empirical information” (AK 28:1020 ), Transcendental
Theology can do no more than attribute to God “what is true of him as
a thing in general” (AK 28:1020 ). That is, its concept of God
is just that of unconditioned quality, quantity, modality, and
Absent all “information” about the conditioned, Transcendental
Theology is thus without the resources to develop the concept of God
used in either Natural or Moral Theology, i.e, the “wise author of
nature” or the judge and “ruler” of nature, respectively (AK 28:452
, AK 28:596 , AK 28:1002 ). Consequently, Kant
claims that Transcendental Theology is inadequate, yielding “only a
silhouette of a theology” (AK 28:605, AK 28:452 ). Its
conception of God is “useless” (AK 28:596 ), “unusable” (AK
28:452 ), and “quite superfluous to us” (AK 28:1020 ). For
it provides us only with the god of Deism, and according to the
lectures, this God is “useless” and “unusable”.
Hence, despite the familiar-seeming term, Kant does not mean by
“Deism” how it was typically used by the British. Their Deism is
rather much more akin to what Kant means by “Theism”, as the outcome
of Natural (vs. Transcendental) Theology. That is, Kant maintains in
the Critique of Pure Reason that our picture of nature as having
systematic unity commits us to seeing nature “as if” it were created
by a “Wise Author” (A644/B672–A645/B673).