reductio ad absurdum
Disproof through impossibility
Reductio ad absurdum is a method of argument that disproves a proposition by showing it leads to absurd or contradictory conclusions.
You assume something is true, follow its logic to an impossible result, and thereby demonstrate the assumption must be false: If we allow students to retake this exam, we'd have to let them retake every exam forever.
The phrase is Latin for "reduction to absurdity." Often shortened to reductio.
Conclusion from premises
- syllogismFormal deductive argument structure
- inferenceConclusion reached through reasoning
- validityQuality of being sound
- soundnessReliability of structure
premise · conclusion · negation · contradiction · antithesis
Point challenging another's position
- refutationDisproving a statement
- rebuttalFormal response disputing claims
- disproofEvidence showing falsehood
- contradictionOpposing claims, incompatible together
objection · critique · debunk · dismantle · disputation · contention · polemic · dialectic
Opposing claims, incompatible together
- impossibilityState of being unachievable
- implausibilityState of seeming unlikely
- nonsensicalWithout coherent meaning
- ludicrousAbsurdly unreasonable or inappropriate
preposterous · ridiculous · illogical · incoherence · self-defeating · untenable · paradox · incongruity
Ancient Athenian questioning philosopher
- ZenoGreek paradox thinker
- AristotleGreek founder of formal logic
- dialecticLogical argument through opposition
- epistemologyTheory of knowledge
Demonstration of truth
- theoremDemonstrated logical conclusion
- axiomSelf-evident starting principle
- lemmaBase form, or helper theorem
- corollaryLogical natural consequence
conjecture · demonstration · Euclid · irrationality · Cantor
deduction
Conclusion from premises
- syllogismFormal deductive argument structure
- inferenceConclusion reached through reasoning
- validityQuality of being sound
soundness · premise · conclusion · negation · contradiction · antithesis
counterargument
Point challenging another's position
- refutationDisproving a statement
- rebuttalFormal response disputing claims
- disproofEvidence showing falsehood
contradiction · objection · critique · debunk · dismantle · disputation · contention · polemic · dialectic · cross-examination
contradiction
Opposing claims, incompatible together
- impossibilityState of being unachievable
- implausibilityState of seeming unlikely
- nonsensicalWithout coherent meaning
ludicrous · preposterous · ridiculous · illogical · incoherence · self-defeating · untenable · paradox · incongruity · self-refuting
Socrates
Ancient Athenian questioning philosopher
proof
Demonstration of truth
- theoremDemonstrated logical conclusion
- axiomSelf-evident starting principle
- lemmaBase form, or helper theorem
corollary · conjecture · demonstration · Euclid · irrationality · Cantor
equivocation
Ambiguous language avoiding commitment
reductio ad absurdumbuilding up
Increasing gradually
confirmation · corroboration · substantiation · buttressing · vindication
reduce, absurd, reduced, reduction, reducing, absurdity, reduces, absurdly, reductive