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Origin and history of deduction

deduction(n.)

early 15c., deduccioun, "a bringing, a leading;" mid-15c., "action of deducting; a taking away, a number or amount subtracted," from Old French deduction (Modern French déduction) and directly from Latin deductionem (nominative deductio) "a leading away, an escorting; a diminution," noun of action from past-participle stem of deducere "lead or bring away or down; derive" (in Medieval Latin, "infer logically"), from de "down" (see de-) + ducere "to lead," from PIE root *deuk- "to lead."

Meaning "that which is deducted" is from 1540s. As a term in logic, "derivation as a result from a known principle, an inference, conclusion," 1520s, from Late Latin use of deductio as a loan-translation of Greek apagoge. Related: Deductional.

also from early 15c.

Entries linking to deduction

de-

active word-forming element in English and in many verbs inherited from French and Latin, from Latin de "down, down from, from, off; concerning" (see de), also used as a prefix in Latin, usually meaning "down, off, away, from among, down from," but also "down to the bottom, totally" hence "completely" (intensive or completive), which is its sense in many English words.

As a Latin prefix it also had the function of undoing or reversing a verb's action, and hence it came to be used as a pure privative — "not, do the opposite of, undo" — which is its primary function as a living prefix in English, as in defrost (1895), defuse (1943), de-escalate (1964), etc. In some cases, a reduced form of dis-.

*deuk-

Proto-Indo-European root meaning "to lead."

It might form all or part of: abduce; abducent; abduct; abduction; adduce; aqueduct; circumduction; conduce; conducive; conduct; conductor; conduit; deduce; deduction; dock (n.1) "ship's berth;" doge; douche; ducal; ducat; Duce; duchess; duchy; duct; ductile; duke (n.); educate; education; induce; induction; introduce; introduction; misconduct; produce; production; reduce; reduction; seduce; seduction; subduce; subduction; taut; team (n.); teem (v.1) "abound, swarm, be prolific;" tie (n.); tow (v.); traduce; transducer; tug; Zugzwang.

It might also be the source of: Latin dux (genitive ducis) "leader, commander," in Late Latin "governor of a province," ducere "to lead;" Old English togian "to pull, drag," teonteon "to pull, drag;" German Zaum "bridle," ziehen "to draw, pull, drag;" Middle Welsh dygaf "I draw."