This merely preliminary determination of the finitude of human reason shows up in Kant only in passing and usually in a phrase that he repeats from time to time: “. . . for us human beings, at least.” But nonetheless, Kant’s entire problematic is contained in this determination, and we will understand nothing about Kant’s philosophy unless we keep in mind its crucial effects. As a finite being—substantia finita (creata)—the human subject has not produced the world that is out there. Rather, the human subject has been produced along with the other things and has been placed into the world with them. To the degree that these things have a relation to intellect, they have it primarily only because they have been created. They have such a relation of essence only to the intellectus archetypus, since they did not bring themselves before that intellect but just the opposite. As finite, these beings cannot, in the primary sense of intuition, produce and therefore know each other, but insofar as they are created, whether as material or spiritual substances, the path of intuition in the radical sense is denied to them. Instead they have to announce themselves to each other. The commercium between these worldly things is based on this announcing of one for the other. As having been created, they can merely act upon one another, and they must do so if there is to be any exchange between them. This acting-upon, when it is done by an entity that can represent things through ideas, is a matter of giving information about something. With a material entity this announcement regards their kind of being, and it must be addressed to an entity that is capable of receiving such an announcement. It must be related to a receptivity, a capability of being given objects that are material. This ability-to-be-given-something (i.e., intuition) is sensibility [Sinnlichkeit]. The basic element of sensibility is sensing, i.e., sensation [Empfindung]. That’s the basis on which the commercium is possible; it is that whereby one sensibility can be present to another. According to Kant, sensations are representations (ways of having objects) “that are caused by the presence of a thing” (Reflexionen, vol. 2, no. 315). By way of interpretation, we have to [117] say the reverse: In sensing, sensibility as intuition is [a priori] open to the presence of things.
Knowing necessarily entails that the things themselves are present in some way and that they announce their presence {Anwesenheit}. This means that knowledge is necessarily intuition. And for that reason a finite subject’s knowledge is necessarily founded on sensibility, that whereby the finite knower can first be “open-to-the-world” at all.
If it is to know at all, the finite being (the human being) must have an intuitus. But as finite, this entity is denied the intuitus originarius and has only an intuitus derivativus. For a “true Kantian” who is concerned only with validities and categories, this fact is a ghastly state of affairs—and interpreting Kant in this way is finally even more ghastly.