PHILOS 31 Lecture Notes - Lecture 4: List Of Cluedo Characters, Natural Deduction, Line Number
Document Summary
Valid argument: if all premises are true, the conclusion must be true. It is impossible for the premises to all be true and the conclusion false. We will use a natural deduction system to show that arguments are valid. Natural deduction systems more closely resemble the way that people think and argue. A proof, or derivation, consists of a series of lines, each which is justified by a rule of our system. A derivation has 3 columns: line number, formla, justification. Miss scarlet is in the billiard room. Either the rope is in the study or plum didn"t do it. If plum didn"t do it, then mustard did. If scarlet is in the billiard room, then the rope isn"t in the study. If scarlet was in the billiard room, then the rope isn"t in the study. S: scarlet is in the billiard room. R: mustard did it: show: r, s, s ~t, ~t, t v ~p, ~p, ~p r, r.
