PHI 1101 Lecture Notes - Lecture 10: Modus Ponens, Modus Tollens, Syllogism
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PHI 1101 Full Course Notes
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Phi1101 chapter 4: some valid argument forms. Arguments based on mathematics (mark has twice as many cats as susan. Susan has three cats; therefore mark has six cats) Arguments from definition: truth of conclusion is guaranteed by definition. Categorical syllogism: two part argument with each statement starting the with all , some , Sentential (propositional) deductive arguments: modes pones, modes tollens, hypothetical syllogism, disjunctive syllogism, constructive dilemma, conjunction, simplification, addition. Statement letters: p, q, r, s v. ~ p v ~ q (p q) r (p v q) ~ (r s) If q, then r. therefore, if p, then r. o o o: p or q. Not p. therefore, not q: either p or q. If p, then r. if q, then s. therefore, either r or s: p. q. Therefore, p and q: p and q. Two invalid argument forms: denying the antecedent (da) Not p. therefore, not q. o o: affirming the consequent (ac)