•
Valid Argument-Forms
–
Modus ponens (method of
affirming):
•
Premises: p à q and p, conclusion: q
–
Modus tollens (method of
denying):
•
Premises: p à q and ~q, conclusion:
~p
–
Disjunctive addition:
•
Premises: p, conclusion: p
| q
•
Premises: q, conclusion: p
| q
–
Conjunctive simplification:
•
Premises: p & q,
conclusion: p, q
–
Disjunctive Syllogism:
•
Premises: p | q and ~q,
conclusion: p
•
Premises: p | q and ~p,
conclusion: q
–
Hypothetical Syllogism
•
Premises: p à q and q à r, conclusion: p à r
–
Dilemma: proof by division
into cases:
•
Premises: p | q and p à r and q à r, conclusion: r
