VALID FORMS | INVALID FORMS |
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Direct Reasoning AB A B One premise is an if...then statement, the other premise affirms the antecedent, and the conclusion affirms the consequent. | Fallacy of the Converse AB B A One premise is an if...then statement, the other premise affirms the consequent, and the conclusion affirms the antecedent. |
Contrapositive Reasoning AB ~B ~A One premise is an if...then statement, the other premise denies the consequent, and the conclusion denies the antecedent. | Fallacy of the Inverse AB ~A ~B One premise is an if...then statement, the other premise denies the antecedent, and the conclusion denies the consequent. |
Transitive Reasoning AB BC AC One premise is an if...then statement, another premise is an if...then statement whose antecedent matches the consequent of the other premise, and the conclusion results from this chain of reasoning. | False Chains AB AC BC AB CB AC An incorrect attempt at Transitive Reasoning, in which two if...then premises agree in the antecedent, or agree in the consequent. |
Disjunctive Syllogisms AB ~B A AB ~A B One premise is an "or" statement, the other premise denies part of the "or" statement, and the conclusion affirms the other part. | Disjunctive Fallacies AB B ~A AB A ~B One premise is an "or" statement, the other premise affirms part of the "or" statement, and the conclusion may affirm or deny the other part. |