1002 Lecture : philosophy note
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Philosophy 212 (001) uw introduction to logic. Q p: dual of ~p and of ~(p v ~q) the dual of ~p is ~ ~~p. ~(p v ~q) is ~~(~p & ~~q). (note that before a dual can be formed by removing ~ there have to be enough ~"s to remove. A sentence can have more than one contradictory if it is a negation. Both p and ~~p are contradictories of ~p. Since ~p q is not a negation but a conditional, it has only one contradictory, the sentence that is its negation (and no other). Department of philosophy: p q, ~~p q, p ~q, ~(p ~q, ~(~p q, for each of the following, circle t if the sentence is true or f if the sentence is false. Every argument whose conclusion is logically true is valid. Every argument with true premises and a true conclusion is valid. T f c. every sound argument has a true conclusion.