deduction
dih-DUK-shun
/dɪˈdʌk.ʃən/
The process of reasoning from general principles or premises to a specific, logically necessary conclusion.
Deduction guarantees truth if the premises are true; it moves from the general rule down to the specific instance.
The story behind the word. Formed from Latin 'deducere' ('to lead down'), deduction literally leads your mind down from a general truth top-level rule to a specific conclusion underneath it.
Word relationships
- derivation: Derivation focuses on tracing something back to its source, whereas deduction emphasizes the step-by-step logical movement toward a conclusion.
- induction: Induction reasons from specific observations to a general rule, whereas deduction goes from general rules to specific instances.
Commonly confused with
- induction: Deduction moves top-down (general to specific with logical certainty); induction moves bottom-up (specific to general with probability).
Word family
- deduce (verb): To arrive at a conclusion by reasoning.
- deductive (adjective): Pertaining to or characterized by deduction.
Collocations
- logical deduction
- process of deduction
- by deduction
Idioms & expressions
- by deduction alone
Example sentences
- "By pure deduction, the physicist calculated the mass of the unobserved particle based on established laws of motion." Scientific reasoning
- "It has long been an axiom of mine that the little things are infinitely the most important, provided you can bring deduction to bear." Classic Mystery
Memory hook
DE-duction moves DE-wn (down) from a big general rule to a small specific fact. Leading down from rules to facts.
When not to use
Do not use 'deduction' when you are making a probabilistic guess based on clues—that is usually 'induction' or 'abduction'. Sherlock Holmes actually used abduction/induction, despite his famous claim of using 'deduction'.
Fun facts
- In tax law, a 'deduction' takes away or leads down an amount from your taxable income—a literal parallel to the logical meaning.
Take your vocabulary further with LangBlitz
Our English vocabulary app: FSRS spaced repetition, 5,000+ curated words across 119 topic groups, CEFR A1 to C2. Explore your mastery with the beautiful Vocabulary World feature.