Understanding (Verstand) is defined only in its logical or discursive employment. Kant wisely defers all reference to its more fundamental synthetic activities. In us (bei uns) is an indirect reference to the possibility of intellectual (non-sensuous) intuition which is further developed in other parts of the Aesthetic.[355] Sensuous intuition is due to affection by an object. In intellectual intuition the mind must produce the object in the act of apprehending it.[356]
Kant’s definition of intuition applies, as already noted, only to empirical intuition. He proceeds[357] to define the relation in which sensation (Empfindung) stands to empirical intuition. What he here says amounts to the assertion that through sensation intuition acquires its object, i.e. that sensation is the content of intuition. And that being so, it is also through sensation that empirical intuition acquires its relation to the object (= thing in itself) which causes it. (That would seem to be the meaning of the ambiguous second sentence; but it still remains uncertain whether the opposition intended is to pure or to intellectual intuition.) If this interpretation of the paragraph be correct, sensation is counted as belonging exclusively to the content side of subjective apprehension. But Kant views sensation in an even more definite manner than he here indicates. Though sensation is given, it likewise involves a reaction of the mind.
“Whatever is sensuous in knowledge depends upon the subject’s peculiar nature, in so far as it is capable of this or that modification upon the presence of the object.”[358]
Thus for Kant sensation is a modification or state of the subject, produced by affection through an object. The affection produces a modification or state of the subject, and this subjective modification is the sensation.
“Sensation is a perception [Perception] which relates itself solely to the subject as the modification of its state.”[359]
This view of sensation, as subjective, was universally held in Kant’s day. He accepts it without argument or question. That it could possibly be challenged never seems to have occurred to him. He is equally convinced that it establishes the existence of an actually present object.
“Sensation argues the presence of something, but depends as to its quality upon the nature of the subject.”[360] “Sensation presupposes the actual presence of the object.”[361]
Kant’s view of sensation, as developed in the Aesthetic,[362] thus involves three points: (1) It must be counted as belonging to the content side of mental apprehension. (2) Though a quality or content, it is purely subjective, depending upon the nature of our sensibility. (3) It is due to the action of some object upon the sensibility.
Kant distinguishes between sensation (Empfindung) and feeling (Gefühl).[363] It had been usual to employ them as synonyms.
“We understand by the word sensation an objective representation of the senses; and in order to preclude the danger of being misunderstood, we shall denote that which must always remain merely subjective and can constitute absolutely no representation of an object by the ordinary (sonst üblichen) term feeling.”[364]