Rule of Inference Laws for True Propositions List

Modus Ponens

p

p ⇒ q

⸫ q

Modus Tollens

¬q

p ⇒ q

⸫ ¬p

Hypothetical Syllogism

p ⇒ q

q ⇒ r

⸫ p ⇒ r

Validity

There is no way when premises are assigned T/F such that:

1) All premises evaluate to TRUE

2) Conclusion evaluates to false