Deductive Reasoning
Reasoning from one or more premises to reach a certain conclusion. If the premises are true, then the deduction is necessarily true — it is "top-down" (in contrast with 'Induction' which is "bottom-up").
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Origin
The formal study of deductive reasoning was established by Aristotle in his logical works known as the Organon, particularly his Prior Analytics (c. 350 BCE), where he developed the theory of the syllogism — a structured argument in which a conclusion follows necessarily from premises. Aristotle's framework defined what it means for a conclusion to follow necessarily, rather than probabilistically. It dominated Western logic for nearly two millennia, until Gottlob Frege modernized formal logic in the 1880s.
Updated February 22, 2026