¶ … Pure Reason underscores the theory of Immanuel Kant that cognition depends on the employment of transcendental processes, which are contingent of the concept of categories. Kant's categories describe the phenomenon of pure understanding. For Kant, pure understanding is the state that permits and defines the corridor of reality as it is realized in the human mind. In The Critique of Pure Reason Kant seemed more interested in stating the existence of the categories than in defining them: "I purposely omit the definitions of the categories in this treatise. I shall analyze these conceptions only so far as is necessary for the doctrine of method, which is to form a part of this critique." Kant was content to allow a sweeping depiction of the categories rather than delve into exhaustive subtleties of them. Comprehending Kant's categories requires an appreciation of his starting point, which was a response to the prevailing philosophical tenor of his day. This complexion comprised the rationalism of philosopher titans Descartes, Leibniz and Spinoza, spiced with the skepticism and empiricism of David Hume. It was Hume's celebration of the humanness of the individual that served as the beacon of inspiration for Kant. This humanness placed priority on desires and passions (rather than reason) and called attention to the subjectivity of human experience.

Operating within this philosophical orbit Kant enlarged the sphere of the philosopher. He began with the context -- in broadest terms -- of the philosopher. Thus, he began with space and time. Humans were not born into a vacuum, nor could ever live in a vacuum. By observing experience in the realm of space and time and recognizing that space and time encompassed experience, Kant set out to determine what can be known and how knowledge is acquired.

In reading Kant, assuming common usage of terms can lead one astray. Kant defines experience in specific scientific terms. Experience, Kant argued, comprises sensory input and a conceptual element. Sensory input gives rise to intuitions, which in turn form sensibilities. Kant distinguishes sensations from concepts. This represented a significant departure from Kant's predecessors, who viewed intuitions and perceptions as interwoven with concepts or interrelated to concepts in some way. For Kant, intuitions without concepts are vacuous as are concepts without intuition.

Kant took subjectivism to mind-bending places by asserting that time, space and causation constitute a form that the mind creates to understand experience. The rationalists, on the other hand, viewed time, space and causation as constituting external reality, separate from the mind.

Now, how does the mind, intuition structured with concepts, think of an object? It needs a "category," Objects must appear to us via these sensible forms in order to be known. Hence, objects can only be known as they appear and not as they absolutely are in reality, which Kant termed "noumena." Humans are capable of thinking about but not knowing noumena, Kant claimed.

Kant arranged the categories, which he frequently called "conceptions of the understanding," into four subcategories. Kant groups together the first two "classes" of categories. The first class is called "Of Quantity," which comprises three subcategories: 1) Unity; 2) Plurality; 3) Totality. The second class of the first group is called "Of Quality," which comprises three subcategories: 1) Reality; 2) Negation; 3) Limitation. The first category, "Of Quantity," Kant entitles "mathematical" and "relates to objects of intuition -- pure as well as empirical." The second category, "Of Quality," Kant entitles "dynamical" and relates "to the existence of these objects, either in relation to one another, or to the understanding." The first class of category, "Of Quantity," has no "correlates," but the second class of category, "Of Quality," does have correlates.

The third category, Kant says, is a combination of the first two categories. The third category is called, "Of Relation," which comprises three subcategories: 1) Of Inherence and Subsistence (substantia et accidens); 2) Of Casuality and Dependence (cause and effect) Of Community (reciprocity between the agent and patient). Kant is careful to point out that the third category is not deduced but a "primitive conception of the pure understanding." Kant does not gloss the fourth category.

Kant defines and explains these categories in relative abbreviated length. He is most concerned with the function of categories. That is because his chief aim in The Critique of Pure Reason is to explore and define the scope of pure reason. In so doing, Kant catalogues the restrictions of reason. With these limitations known, it is then possible to comprehend the possibilities of knowledge.

In explaining the possibilities of knowledge Kant employs terminology of his predecessors, who in turn borrowed...

Knowledge, according to Aristotle, derived from two types of judgments: 1) Synthetic judgment: formulated on a synthesis of known facts; 2) Analytic judgments: formulated on analysis of subjects without drawing on experience. Before Kant the consensus among philosophers was that synthetic judgments were a posteriori (acquired from experience) and that analytic judgments were a priori (acquired outside of experience). Kant famously contends that synthetic judgments can be a prior. The most notable example of occurrence is in the field of mathematics and the principles of science. The oft cited example is the equation 3x4=12. Kant would argue that this equation represents synthetic a priori knowledge because it holds a universal truth that is knowable outside of experience. It would be synthetic because the concept of 12 is not contained in the concept of 3x4.
The comparison with Aristotle is informative. Kant could very well have been seeking an alignment by means of departure with Aristotle. The expansion of the thinking of synthetic judgments would be a positive example of this. However, the entire notion of categories, for Kant, stems from Aristotle in a way that may be more imitative than soundly required. Says Kant in The Critique of Pure Reason: "…there arise exactly so many pure conceptions of the understanding, applying a priori to objects of intuition in general, as there are logical functions in all possible judgments. For there is no other function or faculty existing in the understanding besides those enumerated in that table. These conceptions we shall, with Aristotle, call categories, our purpose being originally identical with his, notwithstanding the great differences in the execution."

Later in the passage Kant nods his respects to the king of philosophy while suggesting the benefit of a preferred course. "It was a design worthy of an acute thinker like Aristotle, to search for these fundamental conceptions. Destitute, however, of any guiding principle, he picked them up just as the occurred to him, and at first hunted out ten, which he called categories (predicaments). Afterwords he believed that he had discovered five others, where were added under the name of post predicaments. But his catalogue still remained defective."

The following comprise Aristotle's categories: 1) substance; 2) quantity; 3) qualification; 4) relative; 4) where; 5) when; 6) being-in-a-position; 7) having; 8) doing; 9) being-affected. Aristotle's and Kant's categories apply to different things. The list of Aristotle was designed to clarify possible contents of propositions. Meanwhile, Kant's list was not intended to clarify the types of things that humans think about. Rather Kant's list of categories was intended as a collection of the possible logical properties of propositions. In other words, Kant's categories aimed to describe various formal features of thought. Thus, Kant's usage of category might better apply to forms.

The central distinction between the two sets of categories, those of Aristotle and those of Kant, lies the respective purposes. Aristotle's categories aimed to identify the subjects of thinking, whereas Kant's categories aimed to identify how things are thought about.

There are other distinctions. Aristotle's categories become acquired possessions while Kant's categories are forces of forms, which are innate. In this vein, Aristotle composed his list of categories as an empiricist would observe objective phenomena. Kant composed his list of categories as a rationalist would predict subjective phenomena. Kant's categories (or primitive conceptions of the pure understanding) are really instincts, which allow for thoughts and thus, control our thoughts.

What possibilities do the categories engender? An interesting question, to be sure. The categories are necessary for possible experience and Kant takes the objects of possible experience to be appearances. Still, Kant's appearances would seem to be intelligible exclusively in a context in which it is a priori knowledge, not experience, assumes the greatest likelihood. This provides the context in which Kant considers the categories necessary for possible experience, so long as Kant appearances are universally accepted in terms of the possibility of a priori, not empirical, knowledge.

The process of understanding Kant's categories must inevitably proceed beyond the overarching function of them, as a collective unit. This process naturally proceeds to the particulars. Surely, the identity and number of the categories should be regarded as significant. Curiously, Kant's categories seem to be static forms that simply act as a portal for knowledge. However, implicit in the identity, order and structure of the categories, is the behavior of the categories. If this is a non-issue, then would it not follow that the categories would not only be static but also…