Arguments

Universal syllogism

An Argument form. Is always valid. All P's are Q's. All Q's are R's. All P's are R's.

Denying the anticedent

An argument form. Is always invalid. If A then B. Not A, so not B

Affirming the consequent

An argument form. Is always invalid. If A, then B. B, so therefore A.

Hypothetical syllogism

An argument form. Is always valid, and has hypothetical premises and a hypothetical conclusion. If A, then B. If B, then C. Therefore, if A, then C.

chain argument

An argument form. Is always valid. A. If A then B. If B then C. So C.

Disjunctive syllogism

An argument form. Is always valid. Either A or B is true. Not A, so B.

Modus Ponens

An argument form. Is always valid. If A then B. A, so B.

Modus Tollens

An argument form. Is always valid. If A, then B. Not B, so not A

Predicate instantiation

An argument form. Is always valid. All P's are Q's. J is a P, so J is a Q.