hypothetical or conditional syllogisms

hypothetical or conditional syllogisms

syllogism

a deductive argument pattern consisting of two premises an a conclusion

hypothetical syllogism

a syllogism that has a condition as at least one premise

Valid forms …

Modus Ponens (if p then q - p - therefore q)

Modus Tollens (if p, then q - not -q, therefore not -p)

Chain Argument (if p, then q - if q, then r - therefore, if p, then r)

Invalid forms….

Affirming the consequent ( if p, then q - p - therefore p)

Denying the antecedent ( if p, then q - not-p - therefore not-q

Broken chains ( no single bad form, but the middle form has to line up properly)

The general rule is that affirmation validity moves “forward” from the antecedent to the consequent, while the negation validity moves “backward” from the consequent to the antecedent