indirect proof
Disprove the negation
Indirect proof is a method of logical argument that establishes a conclusion by showing its opposite leads to contradiction or absurdity.
Rather than proving something directly, you assume the opposite is true, then demonstrate that assumption produces impossible results.
Also called proof by contradiction or reductio ad absurdum.
To prove the number is even, we assume it's odd and show this creates a contradiction.
- counterexampleInstance disproving a claim
- deductionConclusion from premises
- logical reasoningStructured thought process
- assumeAccept as true
- false assumptionIncorrect foundational belief
negation · suppose · syllogism · symbolic logic · contrapositive · reductio ad absurdum · tautology · paradoxes · truth tables · quantifiers · necessary condition · Boolean algebra · impossible · contradiction · refute · if and only if · theorem · epistemology
- logic rulessyllogism, inference, contraposition, double negation, conjunction
- geometric proofstheorem, axiom, postulate, lemma, corollary
- Proof Theorytheorem, axiom, lemma, corollary, natural deduction
- proofscontrapositive, contradiction, theorem, lemma, corollary
- evidenceevidence, evidence bag, circumstantial evidence, admissible, findings
- logicpremise, premises, conclusion, conclusions, inference