From Late Middle English deducen (to demonstrate, prove, show; to argue, infer; to bring, lead; to turn (something) to a use; to deduct),[1] borrowed from Latin dēdūcere, the present active infinitive of dēdūcō (to lead or bring out or away; to accompany, conduct, escort; (figuratively) to derive, discover, deduce); from dē- (prefix meaning ‘from, away from’) + dūcere (the present active infinitive of dūcō (to conduct, guide, lead; to draw, pull; to consider, regard, think), ultimately from Proto-Indo-European *dewk- (to lead; to draw, pull)).[2]



deduce (third-person singular simple present deduces, present participle deducing, simple past and past participle deduced)

  1. (transitive) To reach (a conclusion) by applying rules of logic or other forms of reasoning to given premises or known facts.
    Synonyms: conclude, infer
    Antonym: induce
    • 1593 September 11, [Robert Persons?], “The Second Parte of This Letter Conteyning Certaine Considerations of State vppon the Former Relation”, in [Henry Walpole], transl., Nevves from Spayne and Holland Conteyning an Information of Inglish Affayres in Spayne vvith a Conferrence Made theruppon in Amsterdame of Holland. [], [Amsterdam: A. Conincx], OCLC 287035935, folio [29], recto and verso:
      [T]he puritan buyldeth directly vpon the proteſtants firſt groundes in religion, & deduceth therof clearly and by ordinary conſequence al his concluſions, which the proteſtant cannot deny by divinity, but only by pollicy & humane ordination, or by turning to catholique anſwers contrary to ther owne principles: []
    • 1605, Francis Bacon, “The Second Booke”, in The Tvvoo Bookes of Francis Bacon. Of the Proficience and Aduancement of Learning, Diuine and Humane, London: [] [Thomas Purfoot and Thomas Creede] for Henrie Tomes, [], OCLC 932932554, folio 110, verso:
      [T]hoſe principles or firſt poſitions, have no diſcordance with that reaſon, which draweth downe and diduceth the inferiour poſitions.
    • 1650, Thomas Browne, “Of the Great Climactericall Year, that is, Sixty Three”, in Pseudodoxia Epidemica: [], 2nd edition, London: [] A[braham] Miller, for Edw[ard] Dod and Nath[aniel] Ekins, [], OCLC 152706203, 4th book, page 187:
      Laſtly, One way more there may be of miſtake, at that not unuſuall among us, grounded upon a double compute of the year; the one beginning from the 25 of March, the other from the day of our birth unto the ſame again, which is the naturall account. Now hereupon many men frequently miſcaſt their daies; for in their age they diduce the account not from the day of their birth, but the year of our Lord, wherein they were born.
    • 1651, Thomas Hobbes, “Of Counsell”, in Leviathan, or The Matter, Forme, & Power of a Common-wealth Ecclesiasticall and Civill, London: [] [William Wilson] for Andrew Crooke, [], OCLC 895063360, second part (Of Common-wealth), page 132:
      Counsell, is where a man ſaith, Doe, or Doe not this, and deduceth his reaſons from the benefit that arriveth by it to him to whom he ſaith it. And from this it is evident, that he that giveth Counſell, pretendeth onely (whatſoever he intendeth) the good of him, to whom he giveth it.
    • 1685 April 24, [John] Wallis, “A Discourse Concerning the Air’s Gravity, Observd in the Baroscope, Occasioned by that of Dr. [George] Garden; []”, in Philosophical Transactions: Giving Some Accompt of the Present Undertakings, Studies and Labours of the Ingenious in Many Considerable Parts of the World, volume XV, number 171, Oxford, Oxfordshire: [] Sam[uel] Smith  []; and Hen[ry] Clements [], published 20 May 1685 [Julian calendar; 30 May 1685], DOI:10.1098/rstl.1685.0033, OCLC 630046584, page 1007:
      From the comparative weight or lightneſs of the Air at different times, he deduceth alſo the riſing and falling of Vapours in it.
    • 1689 (indicated as 1690), [John Locke], “No Innate Principles in the Mind”, in An Essay Concerning Humane Understanding. [], London: [] Eliz[abeth] Holt, for Thomas Basset, [], OCLC 153628242, book I, § 9, page 6:
      But how then can thoſe Men think the uſe of Reaſon neceſſary to diſcover Principles that are ſupposed innate, when Reaſon (if we may believe them) is nothing elſe, but the Faculty of deducing unknown Truths from Principles or Propoſitions, that are already known?
    • 1756, “An Abstract of the Reciprocal Duties of Representatives and Their Constituents, on Constitutional Principles”, in A New System of Patriot Policy. Containing the Genuine Recantation of the British Cicero. [], London: [] Jacob Robinson, [], OCLC 62428299, section IV, page 39:
      Now Principles, when deduced by Diſcourſe of ſound Reaſon, may, from the Content of Mankind, take the Name and Force of a Law; but the Faculty which deduceth thoſe Principles, cannot with the leaſt Propriety be deemed a Law. This is confounding Cauſes with Effects, and attributing the Property to the Faculty creating, which only belongs to the Subject created.
    • 1831 October 31, [Mary Shelley], “Letter IV. To Mrs. Saville, England.”, in Frankenstein: Or, The Modern Prometheus (Standard Novels; IX), 3rd edition, London: Henry Colburn and Richard Bentley, [], OCLC 858441409, page 17:
      I do not know that the relation of my disasters will be useful to you; yet, when I reflect that you are pursuing the same course, exposing yourself to the same dangers which have rendered me what I am, I imagine that you may deduce an apt moral from my tale; one that may direct you if you succeed in your undertaking, and console you in case of failure.
  2. (transitive) To examine, explain, or record (something) in an orderly manner.
  3. (transitive, archaic) To obtain (something) from some source; to derive.
  4. (intransitive, archaic) To be derived or obtained from some source.
    • 1766, William Blackstone, “Of Title by Purchase, and First by Escheat”, in Commentaries on the Laws of England, book II (Of the Rights of Things), Oxford, Oxfordshire: [] Clarendon Press, OCLC 65350522, page 256:
      [B]y the ſtatute 7 Ann. c. 21 [] it is enacted, that, after the death of the pretender, and his ſons, no attainder for treaſon ſhall extend to the diſinheriting any heir, nor the prejudice of any perſon, other than the offender himſelf: which proviſions have indeed carried the remedy farther, than was required by the hardſhip above complained of; which is only the future obſtruction of deſcents, where the pedigree happens to be deduced through the blood of an attainted anceſtor.
  5. (transitive, obsolete) To take away (something); to deduct, to subtract (something).
    to deduce a part from the whole
  6. (transitive, obsolete, based on the word’s Latin etymon) To lead (something) forth.

Usage notesEdit

  • Regarding sense 1 (“to reach (a conclusion)”):
    • For example, from the premises “all good people believe in the tooth fairy” and “Jimmy does not believe in the tooth fairy”, we deduce the conclusion “Jimmy is not a good person”. This particular form of deduction is called a syllogism. But note that in this instance we reach a false conclusion by correct deduction from a false premise.
    • It is the nature of corollaries that they are usually deducible.


Alternative formsEdit

Derived termsEdit

Related termsEdit



  1. ^ dēdūcen, v.”, in MED Online, Ann Arbor, Mich.: University of Michigan, 2007.
  2. ^ Compare “deduce, v.”, in OED Online  , Oxford, Oxfordshire: Oxford University Press, 1894; “deduce, v.”, in Lexico, Dictionary.com; Oxford University Press, 2019–2022.

Further readingEdit





  1. third-person singular present indicative of dedurre




  1. second-person singular present active imperative of dēdūcō



Borrowed from Latin deducere, French déduire, with conjugation based on duce.


a deduce (third-person singular present deduce, past participle dedus3rd conj.

  1. (transitive) to infer, deduce (to conclude by reasoning or deduction, as from premises or evidence)





  1. inflection of deducir:
    1. third-person singular present indicative
    2. second-person singular imperative