PHIL 2110 Lecture Notes - Lecture 10: Reductio Ad Absurdum, If And Only If, Conditional Proof

• School: University of Guelph
• Department: Philosophy
• Course: PHIL 2110
• Professor: Yussif Yakubu

Document Summary

Conditional proof (cp): to prove a conditional statement, suppose the antecedent as a statement on a separate line, with justification supp/cp. 2 simp: q r 1,3 mp, q. ********remember the indent when supposing!!!!!!: a b, b c, a, b, c. Here, we could have had any statement p for a, q for b, and r for c. 3-5 cp: example: c d, d e e c, c d, d e, c e, e, e, c, e c. More conditional proof examples: ch7 #11: a (a b) b. 2-3 cp supposition discharged: 4. (a b) b. Example: (p&q) r p r: 1. (p&q) r, p, q, p&q, r, q r, r inside supposition. 3,6 mp - wrong b/c cannot, once popped out, use things: 8. P r: so, the example is actually invalid, also, whatever you suppose, that must be part of the conditional statement that you.