Philosophy 1230A/B Lecture Notes - Modus Tollens, Modus Ponens
Document Summary
Modus ponens: if p then q. p. therefore q, if this object is made of copper, it will conduct electricity. This object is made of copper, so it will conduct electricity: p and q are sentence letters, translate or represent statements. Affirming the consequent: if p then q. q. Therefore p: this form is a fallacy making a mistake of reasoning lives in beijing, if jane lives in beijing, then jane lives in china. Modus tollens: if p then q. not-q. Therefore not-p: if betty is on the plane, she will be in the a1 seat. But betty is not in the a1 seat. So she is not on the plane: not valid. Betty could be sitting in a different seat. Denying the antecedent: if p the q. not-p, therefore not-q. If elsie is competent, she will get an important job. So she will not get an important job: not valid.
