Philosophical view that regards reason as the chief source and test of knowledge. Rationalism has long been the rival of empiricism, the doctrine that all knowledge of matters of fact ultimately derives from, and must be tested by, sense experience. As against this doctrine, rationalism holds reason to be a faculty that can lay hold of truths beyond the reach of sense perception, both in certainty and in generality. In stressing the existence of a “natural light,” rationalism also has been the rival of systems claiming esoteric knowledge, whether from mystical experience, revelation, or intuition, and has been opposed to various irrationalisms that tend to stress the biological, the emotional or volitional, the unconscious, or the existential at the expense of the rational.
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