PHI 1101 Lecture Notes - Lecture 4: Modus Tollens, Deductive Reasoning, Modus Ponens

• School: University of Ottawa
• Department: Philosophy
• Course: PHI 1101
• Professor: Sardar Hosseini

Document Summary

We will not cover the material in the section entitled equivalent forms (page 64-75) Common deductive argument types: argument based on mathematics ex: mark has twice as many cats as susan. Mark has six cats: argument from definition- truth of conclusion is guaranteed by definition ex: harold is matilda"s son. Jackson is a liar; therefore, he doesn"t tell the truth: categorical syllogism- syllogism (two premised argument) which each statement starting with all , some , none or ever ex: all humans are mortal. Therefore, socrates is mortal: sentential (propositional) deductive arguments. We introduce the following symbol to represent statements and argument forms: statement letters (sentential variables): p, q, r, s , connectives: v ( ) for grouping. Conjunction ( and", but", yet") = ex: alice rode her bike, and john walked. p q. Disjunction ( or ", either ") = v ex: either alice rode her bike, or john walked. p v q.