>>24710661
You have to understand that Kant's topic is neither empirical-scientific, psychological, nor physiological. His topic is strictly logical, which investigates either the general form of thought as such (general logic) or the general form of thought insofar as it contentful (transcendental logic). Whose thought? No one's in particular. The primary subject of logic is not this or that particular thinker, but the thinker as such or in general. The primary subject of logic abstracts from the given, or contingent, character of the thinker and considers him only insofar he thinks. We know nothing of the one who thinks except this: he thinks. This generic representation of the subject is therefore pure and untinged by any empirical content. A formal and empty represention that is immune to any multiplication. This justifies his generic use of the terms thought, understanding, reason, etc. without referring to any particular person.

Since the primary subject of logic is the thinker überhaupt, the knowledge that logic articulates has nothing to do with the physiognomy of people's heads, or how people do tend to think, or how their brains function. No, what logic articulates is what any thinker must think in order for his activity to count as thinking at all.