Perception of Space
Kant also believed that our experience of space was provided by an innate cat- egory of thought. Kant agreed with Hume that we never experience the physical world directly, but he observed that it certainly seems that we do. For most, if not all, humans, the physical world appears to be laid out before us and to exist independently of us. In other words, we do not simply experi- ence sensations as they exist on the retina or in the brain. We experience a display of sensations that seem to reflect the physical world. The sensations vary in size, distance, and intensity and seem to be distributed in space, not in our retinas or brains. Clearly, said Kant, such a projected spatial arrange- ment is not provided by the sensory impressions themselves.
Sensations are all internal; that is, they exist in the mind alone. Why is it, then, that we experience objects as distributed in space as external to the mind and the body? Again, Kant’s answer was that the experience of space, like that of time, was pro- vided by an a priori category of thought. According to Kant, the innate categories of time and space are basic because they provide the context for all men- tal phenomena, including (as we have seen) causality.
It must be emphasized that Kant did not propose specific innate ideas, as Descartes had done. Rather, he proposed innate categories of thought that orga- nized all sensory experience. Thus, both Descartes and Kant were nativists, but their brands of nativism differed significantly.
