The existence of rocks and dinosaurs independent of human knowledge compels me to reconsider my concept of the world solely as an experience. The world as we know it, as a contingent circumstance, exists only as a result of a real past of which we lack considerable knowledge. It depends, therefore, on real unknowns, including a past that, by virtue of the exclusion of events that did not occur, exhibits precognitive distinction. Unknown rocks and other real and unknown objects indicate the existence of properties that fit our categories prior to the categorization of such properties. The world, therefore, seems to be real independent of knowledge or experience. We seem, furthermore, to have access, through experience and knowledge, to a reality that does not depend on access through experience and knowledge.

To what extent is it possible to know the extent to which our categories reflect properties that precede them?