Priori

Part of speech: adjective, adverb

Definitions

1. A category of reasoning that reaches conclusions based on theoretical premises rather than empirical evidence
2. A philosophical approach that emphasizes knowledge derived from inherent reasoning rather than sensory experience
3. Relating to knowledge or justification that is derived through logical reasoning without needing observational data

Etymology: "Priori" comes from Latin "a priori," literally "from the former" or "from what comes before," used in logic to mean reasoning from general principles to particular conclusions rather than from observed evidence. The contrast with "a posteriori," "from what comes after," reflects the same idea: knowledge that precedes experience versus knowledge drawn from it. Medieval scholastic philosophers used these phrases to describe two directions of proof. An argument that moved from a cause to its effect was reasoning "a priori," while one moving from observed effects back to causes was "a posteriori." The Latin phrases were already established in philosophical use long before English adopted them. In English, the adjective and adverb senses describe knowledge or argument that does not depend on experience, as in a priori truths of mathematics. The phrase was later used loosely to mean "presumed in advance" or "assumed without checking," a sense that writers often use to criticize hasty judgments.

Synonyms: deductive, theoretical, preconceived, innate, a priori

Antonyms: empirical, posteriori, observational, experiential