Kant's Philosophy: Sensitivity, Understanding, and Reason

7. Structure and Function Meet Human Faculty. For Kant, knowledge is a synthesis of concept and experience. When we expect to know by pure concepts, knowledge is empty. When we reduce everything to experience, knowledge is blind. Within the faculty of human knowledge, Kant distinguishes three functions: sensitivity, understanding, and reason, each with a peculiar formation and a particular role in the development of knowledge.

The sensitivity supplies knowledge through the senses. Understanding processes these materials and makes judgments. The reason argues and follows its base.

Sensitivity is the faculty by which humans have cognitive contact with reality. It is the world of the senses, providing the matter of knowledge. Through awareness, the world appears as a multitude of colors, shapes, smells, sounds, etc. This matter has to be processed into knowledge. Empiricists believed that human sensitivity was passive, merely reflecting what the outside world exposed it to. Kant pointed out, however, that such passivity is not credible. Sensitivity includes impressions, but necessarily imprints a certain shape, like a bottle containing liquid prints its own outline.

Empiricism insists that the human mind is a "blank sheet" and that there is nothing in the understanding that was not first in the senses. But it is not a passive blank slate; its own form affects the information that can be inserted into it. You can write or draw with a pencil, pen, or invisible ink, but you cannot record electromagnetic information, which would require a tape and a different nature.

Space and Time as Pure Forms of Feeling

Space and time are pure forms of sensibility. They are pure because they are free of experience, prior to all experience, and the only path through which we receive evidence. They are a priori and necessary forms, essential ingredients of all experience: no human experience can take place outside of space and time.

Space and time, in turn, have a special structure. The structure of space is the "pure being with," and the structure of time is a "succession of pure" moments. This structure is the imprint of space and time on all experience. All our experiences are of objects that are beside each other and that follow one another. Space and time are the coordinates in which all our experience is "directed," but these coordinates are imposed by the subject of knowledge, man. That experience can be otherwise, that what was black yesterday is white today, or that what seemed cold yesterday seems hot today, etc., but that everything has to happen in space and time, is an indication that space and time are a priori, innate, born with us and determine our way of knowing reality.