PHIL 110 Lecture Notes - Lecture 10: Logical Biconditional, Contraposition, Modus Tollens
16 Mar 2017
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Dr mc"s philosophy 110 (1171) part notes, 6#1 . So far, we"ve discussed eight valid argument forms. That means, they work in one direction only. These rules can be applied to entire lines only, not to parts of lines. You cannot use addition to go form a c to (a v b) c. C| a c, (a v b) c. Prove this argument valid: ~a, (c v a) l, a v d, (d v u) c. We also have some rules of inference that work in both directions. W= there was a love affair between the butler and the maid. If the butler didn"t do it, then if the cook didn"t do it, it had to be either the gardener or the maid. The gardener didn"t do it unless the murder weapon was a pitchfork; if the cook did it, the weapon was surely a knife. If the weapon was a revolver, it was neither a pitchfork nor a knife.
