PHIL 230 Lecture Notes - Lecture 4: Formal Grammar, Counterexample

• School: Cal Poly
• Department: Philosophy
• Course: PHIL 230
• Professor: Frank E.Pilling

Document Summary

The validity test: the logic form of the argument is correct, this never change. The conclusive premise test: reasons to believe the premise, this can change as knowledge change. If it rains, then sally takes an umbrella. It rains: sally takes an umbrella. Predicate logic: no repeated declarative sentence. Rex is a dog: rex is a mammal. Valid argument: all a"s are b"s, x is an a. X is a b: if p then q, p. Thursday, january 19, 2017: all a"s are bs, x is not a b. X is not an a: if p then q, not q. Invalid arguments: all a"s are b"s, x is an b. X is a a: all dogs are mammals, rex is a mammal. Rex is a dog: rex can be any other mammal, if p then q, q. P: if rex is a dog then rex is a mammal, rex is a mammal.