EntityQ844118· pop 28· linked from 105 articlesmodus tollensSign in to saveif X implies Y, and Y isn't true, then neither is XConnectionscontrapositionEntityreductio ad absurdumEntityfirst-order logicEntitylogical formEntityLatinEntityInternational Standard Book NumberEntityset theoryEntityancient historyEntitystoicismEntitytheoremEntityTheophrastusEntitylist of Latin phrasesEntitycommutative propertyEntityassociativityEntityfallacyEntitydeductive reasoningEntityBayes' theoremEntityinferenceEntitypropositional calculusEntityKhan AcademyEntityCategoriesClassical logicLatin logical phrasesRules of inferenceTheorems in propositional logic