“What is Categorical about the Categorical?” Updated 3 September 2012

What is Categorical about the Categorical? by Douglas R McGaughey is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License.
Based on a work at criticalidealism.com.

What is Categorical about the Categorical?
On the Sensible and the Supersensible

Human experience is dependent upon the inseparable, yet distinguishable, interaction between two dimensions:  the sensible and the supersensible.  Each dimension must simultaneously make a contribution, or else there can be no experience.  Although we must speak of two dimensions that make our experience possible, we are no more talking about dualism as the explanatory ground of experience than attributing multiple, interacting causes to a physical event shatters the unity of efficient causality.  We would be concerned with dualism only if we succumbed to a Cartesian dual-substance notion of experience, but that would, of course, presume that we had access to such things as substances that could confirm their reality.  Rather, we do not experience substances, only their appearances.  Granted, “hardness” (Unnachgiebigkeit) and “durableness” (Dauerhaftigkeit) are strong indicators of the presence of substance, but we too quickly substitute substance for its appearance.  We live in a world of appearances and a priori synthetic judgment, and any conclusions about the nature and character of substance are among our synthetic judgments either a posteriori or a priori since we cannot experience substances themselves.

These two dimensions appear to be 180° opposite to one another.  The sensible world consists of a set of appearances that are perceptible, material, divisible, measurable, and constantly changing.  The supersensible world consists of a set of “appearances” that are imperceptible, immaterial, indivisible, immeasurable, and, when it comes to concepts, unchanging.  Observation of these contrasting sets of appearances by no means presumes what needs to be proved.  Rather, it is only a contrast between descriptive sets, and it is the task of Critical Idealism to sort out what is necessary and what is purely accidental about these sets of appearances.