PHIL 10 Lecture Notes - Lecture 6: Nsb Di 8, Modus Ponens, Ds 5
Document Summary
Phil 10 lecture 6 chapter 3. Disjunction on one line, negation of one of the disjuncts on another line, can derive new line consisting of other disjunct. 1. (a b) c: a b, c. P ~q: ~q v p, q, p, ~q. Other possibility is that premises aren"t consistent; argument will still be valid because. If they are applied to only true, lines, only produce only true lines. Inference rules, doesn"t matter what happens if lines are applied aren"t all true there won"t be a counter-example row. If you can derive the conclusion you know the argument is valid. Premises are consistent: no counter-example row because there are rows where all premises are t, conclusion is also t on rows. Premises are not consistent: no counter-example row because no row where all premises are t. Ruled out: any row where all premises are t and conclusion is f. so no counter-example row.
