Reductio (short for reductio ad absurdum) is a rhetorical and logical argumentation technique in which one provisionally accepts a proposition for the sake of argument, then demonstrates through valid reasoning that it entails an absurd, contradictory, or unacceptable conclusion — thereby refuting the original proposition. The parameters are: (1) the target proposition to be tested, (2) a chain of reasoning that follows from that proposition without introducing external assumptions beyond those shared by the interlocutor, (3) a conclusion that is demonstrably absurd or self-contradictory. The map of reductio persists through formal education in logic, the pedagogical traditions of dialectic and debate, and its repeated deployment in mathematical proof, philosophical argumentation, and everyday reasoning — cultural practices that teach and preserve the technique across generations. [formal: reductio ad absurdum | substrate: mind | horizon: generations | explicit: yes | epoch: 0.22]
Accepted ontology entry
reductio
Reductio (short for reductio ad absurdum) is a rhetorical and logical argumentation technique in which one provisionally accepts a proposition for the sake of argument, then demonstrates through valid reasoning that it entails an absurd, c…
Definition
Why it is in scope
A method of argumentation in which a proposition is assumed and shown to lead to absurdity or contradiction, thereby disproving it. Human-made logical technique, built to persist through mathematical proof, philosophical dialectic, and formal reasoning disciplines.
Names and aliases
- reductioen · CANONICAL
Relations from this entry
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Reductio ad absurdum is inherently linguistic: it constructs arguments in language that lead to absurdity, using linguistic structure as the mechanism. Remove language and the technique cannot operate — it IS a linguistic operation.
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Reductio ad absurdum requires distinguishing between a proposition and its absurd consequences — the distinction operation is constitutive of the method.
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Reductio ad absurdum is a specific kind of logical argument — the method of proving a proposition by showing its contradiction leads to absurdity. This is a clear specific→general INSTANCE_OF relationship.
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Reductio ad absurdum is a specific form of argumentation that works by demonstrating that a premise leads to an absurd or contradictory conclusion.
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- Created
- Jul 18, 2026, 3:11 AM UTC
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- 3d53dcdd50000d6088a031cb49f8dfcc7f2fb4b429f9e5481fa1929717781aca