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logic

Validity depends only on form

taught

If one instance of a form can have true premises and a false conclusion, every argument with that form is invalid.

Taught in

Requires

Required by

Local knowledge map

Local knowledge map

Affirming a disjunct Affirming the consequent Constructive dilemma Derived rules: MT, DS, DNE, and De Morgan Hypothetical syllogism Modus tollens Quantity and quality of categorical statements Recognizing named forms in everyday arguments Sentence letters and a symbolization key The conditional connective: antecedent and consequent The conjunction rules The disjunction rules Venn diagrams for single categorical statements Addition Conjunction (the argument form) Disjunctive syllogism Modus ponens Simplification The four categorical statement types (A, E, I, O) Why logic uses symbols Validity depends only on form Checking whether a proposed counterexample works Reading "or" as inclusive by default Reading some, all, and none precisely Proving invalidity by swapping in new content Recognizing substitution instances of a form Finding an argument's form Judging validity by searching for a counterexample case

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