PHIL 1636 Lecture Notes - Lecture 6: Modus Ponens, Modus Tollens, Proof Procedure
Document Summary
Natural deduction - a proof procedure by which the conclusion of an argument is validly derived from the premises through the use of rules of inference. Rules of inference - used to justify the steps of a proof. Implication rules - valid argument forms, when the premises of a valid argument form occur during a proof, then we can validly derive the conclusion of the argument form as a justified step in the proof. The statement form ~(p q) is logically equivalent to (~p v. Both types have the same function: to ensure the validity of the steps they are. Proof (also called a deduction or a derivation - a sequence of steps in which each step either is a premise or follows from earlier steps in the sequence according to the rules of inference. A proof is valid if each step is either a premise or is validly derived using the rules of inference.
