LPS 29 Lecture Notes - Lecture 3: Modus Tollens, Modus Ponens, Sentence Clause Structure

• School: UC-Irvine
• Department: Logic and Philosophy of Science
• Course: LPS 29
• Professor: Margaret Gilbert

Document Summary

Lps 29 - lecture 3 propositional logic. Formal logic: the study of argument forms, abstract patterns of reasoning shared by many different arguments. It is not the case that p: either p or q, q. In this case, p and q serve as something called sentence letters. Example: either sally took the apple or roger did. If p, then q: p, q. If he is going to the beach, then i will go to the beach. It is not the case that q: it is not the case that p. It is not the case that p and q. Both cases of modus ponens and modus tollens are valid. However, a form called affirming the consequent is not always valid. If p, then q: q, p. If you are against me, then you are in trouble. In this example, the argument above is invalid, because you can be in trouble for other matters other than being against me.