PHIL 210 Lecture Notes - Lecture 12: Conjunction Elimination, Disjunction Introduction, Disjunction Elimination
21 Feb 2018
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Conjunction in proofs based on our understanding of what the conjunction or means and from the truth tables, we can justify the following principles : 1. principle of conjunction elimination given p and q we can infer p (we can infer q) 2. principle of conjunction introduction given p and q separately we can infer p and q. 4. principle of disjunction elimination given a sentence containing an or write a sentence that does not contain an or. Phil210 page 2 assertion of p or q presents two alternatives. R can be inferred from p or q without any extra assumption without knowing which of p and q holds incorporate this into a rule of inference: pp. 132-135 informal proof by cases. Phil210 page 3 it might seem obvious since we are given small( c) in each disjunct/ possibilities. R follows from each of the two possibilities why the rule of disjunction introduction is useful p. 134 exercises 5. 7-5. 14 p. 135.
