Empirical evidence is a source of knowledge acquired by means of observation or experimentation. Empirical evidence is information that justifies a belief in the truth or falsity of an empirical claim. In the empiricist view, one can only claim to have knowledge when one has a true belief based on empirical evidence. This stands in contrast to the rationalist view under which reason or reflection alone is considered to be evidence for the truth or falsity of some propositions. The senses are the primary source of empirical evidence.
All attempts to derive these pure concepts of understanding from experience, and so to ascribe to them a merely empirical origin, are entirely vain and useless. […]
we can acquire a priori knowledge of objects, as in mathematics, but only in regard to their form, as appearances; whether there can be things which must be intuited in this form, is still left undecided. […]
Only our sensible and empirical intuition can give to them body and meaning.
The term [antinomy] acquired a special significance in the philosophy of Immanuel Kant (1724–1804), who used it to describe the equally rational but contradictory results of applying to the universe of pure thought the categories or criteria of reason that are proper to the universe of sensible perception or experience (phenomena). Empirical reason cannot here play the role of establishing rational truths because it goes beyond possible experience and is applied to the sphere of that which transcends it.
Rationalism is defined as a methodology or a theory “in which the criterion of the truth is not sensory but intellectual and deductive.” Rationalists believe reality has an intrinsically logical structure.