This document discusses rationalism and empiricism as epistemological theories about the source of knowledge. Rationalism holds that we can have substantive a priori knowledge about the world through reason alone, without sense experience. Empiricism denies this and claims that all knowledge must be based on sense experience. The document notes that most rationalists still allow for some knowledge from experience, and empiricists use reasoning, so the distinction is whether substantive knowledge about the world can be attained independently of experience through reason.