“An Introduction to Formal Logic” S:1 E:17 Validity in First-Order Predicate Logic

S:1 E:17 Validity in First-Order Predicate Logic For all of their power, truth tables wont work to demonstrate validity in first-order predicate arguments. For that, you need natural deduction proofs-plus four additional rules of inference and one new equivalence. Review these procedures and then try several examples.