Claim. Kant’s transcendental logic holds that objective knowledge arises when a priori forms of thought (twelve categories) synthesize sense content received through a priori forms of intuition — but things-in-themselves remain unknowable.
Elaboration. Sang Hun Lee summarizes Kant (E. Transcendental Logic). Kant asked how objective knowledge is possible. His answer: through thinking, by means of forms of thought, about sense content received via forms of intuition. Both the forms of intuition (space, time) and the forms of thought are a priori — not derived from experience.
Kant divided judgment into four headings — quantity, quality, relation, modality — each with three forms, yielding twelve forms of judgment. From these he derived twelve forms of thought, or twelve categories — the most basic frameworks through which we think.
Crucially, cognition cannot be achieved by a priori forms alone. A concept is ‘like an empty container’ — meaningless without content. The concept ‘animal’ has no substance until filled by encounter with actual chickens, dogs, sharks. Things-in-themselves send stimuli that produce a manifold of sense qualities; when these are united with the empty concept under a priori forms, the object of cognition is synthesized. We do not know things-in-themselves; we know the synthesized object.
Lee contrasts this with formal logic: formal logic since Aristotle deals with general forms and laws of thought without regard to the object of thought. Kant’s logic, by contrast, is epistemological — its aim is to explain how knowledge about objects is achieved.
The Unification Thought critique (Section III) is that Kant’s scheme is one-sided. For Kant, the object contributes only sense content, and the subject contributes only form. But from Unification Thought’s perspective, the object has both content and form (forms of existence), and the subject has both form and content (image of content). The truthfulness of thinking cannot be guaranteed by a priori forms plus sense content alone — it requires the necessary relationship between humans and all things, both made in the likeness of the Original Image, which produces the correspondence between thought-forms and external-world-forms.
See also. kant-synthesis-as-collation, ut-critique-of-kantian-agnosticism-via-sungsang-hyungsang, logic-is-laws-and-forms-of-thinking