I suggest caution in drawing out Kant's connection with the concept of the noumenon.
- Kant suggests that the concept of noumena can be defended on two
(a) First, its logical possibility:
A254-B310. "The concept of noumenon - that is, of a thing which
is not to be thought as object of the senses but as a thing in itself,
solely through a pure understanding, is not in any way contradictory. For we cannot assert of sensibility that it is the sole possible
kind of intuition."
(b) Secondly, the need to limit sensible experience:
A254-B310. "Further, the concept of a noumenon is necessary to
prevent sensible intuition from being extended to things in themselves, and thus to limit the objective validity of sensible know
". . .to substitute the logical possibility of the concept (namely that
the concept does not contradict itself) for the transcendental possibility of things (namely that an object corresponds to the concept)
can deceive and leave satisfied only the simple-minded."
That takes care of defense (a) above. Note also that in 1 (b) Kant
makes a distinction between our sensibility, which is only one kind
of intuition, and intuition, and claims we cannot say our sensibility
is the only kind of intuition. Implicit is the idea that to be is to
turn up in some intuition: being is appearing, and the thing in
itself merely serves as a guard against limiting things to the
characters they present in our intuition.
- In B307 the noumenon is referred to as "the entirely indeterminate
concepts of an intelligible entity" which often is made into a
"determinate concept of an entity that allows of being known in
a certain (purely intelligible) manner by means of the understand
ing." This making is declared illegitimate. The point is that a
noumenon is now a very indeterminate thing.
- In B307 Kant distinguishes between noumenon in a positive sense
(object present to nonsensous intuition, which is the first edition
meaning, sometimes) and in a negative sense, namely as a limit to
our sensibility, and concludes at B308:
"That therefore which we entitle noumenon must be understood as being such only in a negative sense."
- Even of this negative sense of noumenon Kant says at A255-B310:
"We are unable to comprehend how such noumena can be possible,
and the domain that lies out beyond the sphere of appearances is
empty. . . . The concept of a noumenon is thus merely a limiting
concept, the function of which is to curb the pretensions of sensibility, and it is therefore only of negative employment. At the
same time it is no arbitrary invention; it is bound up with the
limitation of sensibility, though it cannot affirm anything positive
beyond the field of sensibility." (ital. added)
The interesting thing in this passage is the declaration that the
domain beyond the sphere of appearances is not full of things in
themselves, but is empty.
- Finally, A256-B311 (and note that this is a text common to both
editions, and thus even in the first edition, contradicts A249 which
I cited earlier) :
"The division of objects into phenomena and noumena and the
world into a world of the senses and a world of the understanding,
is therefore quite inadmissible in the positive sense. . . . Nonetheless, if the concept of a noumenon be taken in a merely problematic sense, it is not only admissible, but as setting limits to sensibility is likewise indispensable. But in that case a noumenon is
not for our understanding a special (kind) of object, namely an
intelligible object; the (sort of) understanding to which it might
belong is itself a problem." (ital. added)
In his own words the noumenon is not an object or a kind of
object, nor is its nature clear; it is a problem.
I submit that the end of this line of thought would be to drop
the phrase "thing in itself" completely and to replace it with a
term which does not have so many confusing consequences.
Further, I submit that Kant was aware of this, that he did come to
a more functional rather than substantial interpretation of the
thing in itself, and that he struggled to give expression to it.
Running through all of the concepts of the noumenon, even the substantial ones in the first edition, is the fundamental theme of a
function within experience, a dimensional aspect of our awareness
of phenomenal presence. It is necessary to limit the sensibility,
to "curb the pretensions" of the category-structured human intuition. Aside from this function Kant in the end could not assign
any definite meaning to the noumenon, and finally he admitted it.
It just cannot be conceived in any sense as an object. Nor, I
think, can it ultimately be considered as reality in any way as
opposed to appearance, if this reality remains utterly inaccessible
to and ineffable within experience. Hence, a purely experiential
function must be found for it. Kant is an empiricist and always
maintains that only that which relates to experience is meaningful,
only that which turns up in the intuition is real. (Richard F. Grabau, 'Kant's Concept of the Thing in Itself: An Interpretation', The Review of Metaphysics, Vol. 16, No. 4 (Jun., 1963), pp. 770-779: 774-6.)
Richard F. Grabau, 'Kant's Concept of the Thing in Itself: An Interpretation', The Review of Metaphysics, Vol. 16, No. 4 (Jun., 1963), pp. 770-779.
Kant, Critique of Pure Reason, N. Kemp Smith tr. The later translation by Paul Guyer and Allen W. Wood, Cambridge: CUP, 1998, is preferable but I have had to keep to Grabau's text and the modern Cambridge translation is readily available for cross-checking.