Noumenon and Reason

Probably the most important structural distinction in Kant's system is that of Noumenon vs. Phenomenon, which grounds the possibility of Freedom, i. e. of non-Empirical Causality.  However, the concept of Noumenon remains crucially underdeveloped in several respects.  For example, since he establishes that Quantity applies to only Phenomena, any quantification of Noumena is groundless.  Therefore the concept of Universal that he ascribes to the presumably Noumenal Pure Practical Reason is likewise groundless, i. e. if it were descriptive of the conduct of a Rational Automaton, it would entail no Quantification.  He also neglects to consider the significance of the equivalence of the concept of the totality of Phenomena and Spinoza's concept of Natured Nature.  He accordingly neglects to consider the potentially analogous relation between his Noumenal realm and Spinoza's Naturing Nature.  The potential relevance to Kant's doctrine of that relation is if it is similarly one of equivalence, then Pure Practical Reason is nothing but an expression of Spinoza's immanent deity, and, hence, the Noumenal realm is Natural, not Supernatural. Kant's negligence of the Noumenal characteristics of the Principle is graphically illustrated by the ratio of the amount of text in the trilogy and the Groundwork devoted to an exposition of it, versus the amount devoted to matters that are derivative or extrinsic.