Word Confusion: Deduce versus Deduct

Posted November 2, 2015 by Kathy Davie in Author Resources, Editing, Self-Editing, Word Confusions, Writing

This was my problem. When I was working on “Word Confusion: Adduce vs Deduce vs Educe vs Induce“, I was confusing deduce with deduct. It screamed for its own explanation of this confusion.

Word Confusions started as my way of dealing with a professional frustration with properly spelled words that were out of context in manuscripts I was editing as well as books I was reviewing. It evolved into a sharing of information with y’all. I’m hoping you’ll share with us words that have been a bête noir for you from either end. Consider sharing this Word Confusion with friends by tweeting it.

Deduce Deduct
Credit to: Apple Dictionary.com

A magnifying glass, a meerschaum pipe, and a deerstalker cap on a table in front of a fire

Image by Alterego [GFDL or CC-BY-SA-3.0], via Wikimedia Commons

It’s the classic Holmes accessories before Sherlock heads out to deduce.

A black-and-white photograph of a snowy slope with snow-covered trees of different heights

Image by the National Library of Norway has no restrictions on its use and is provided via Wikimedia Commons

You can deduct the difference in the heights of the various trees with an estimate.

Part of Grammar:
See also “Word Confusion: Adduce vs Deduce vs Educe vs Induce

Verb, transitive

Third person present verb: deduces
Past tense or past participle: deduced
Gerund or present participle: deducing

Verb, intransitive & transitive

Third person present verb: deduces
Past tense or past participle: deduced
Gerund or present participle: deducing

Figure it out

Arrive at a fact or a conclusion by reasoning

Draw as a logical conclusion

  • [Archaic] Trace the course or derivation of

Verb, intransitive:
[Usually followed by from] Detract


Verb, transitive:
Subtract or take away an amount or part from a total

Little can be safely deduced from these figures.

They deduced that the fish died because of water pollution.

He cannot deduce his descent wholly by heirs male.

Sherlock Holmes deduced occupations by studying physical characteristics and objects they own.

Verb, intransitive:
The rocky soil deducts from the value of his property.

Verb, transitive:
Once you deduct your expenses, there is nothing left.

The applicable tax has been deducted from the payments.

Adjective: deducible, nondeducible, subdeducible
Adverb: deducibly
Noun: deducibility, deducibleness
Adjective: deductible, deductive, undeducted
Adverb: deductively
Noun: deductible, deductibility, deduction
Verb: prededuct
History of the Word:
Late Middle English in the sense of lead or convey and is from the Latin deducere, from de- (down) + ducere (lead). First known use was between 1375 and 1427 and is from the Latin Latin dēductus meaning brought down or withdrawn, a past participle of dēdūcere.

Deduct and deduce were not distinguished in sense until the mid-17th century.

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C’mon, get it out of your system, bitch, whine, moan…which words are your pet peeves?