Hypothetical Syllogism

Hypothetical Syllogism Your agony starts again….

Hypothetical Syllogism •

Is one whose major premise is a hypothetical proposition and the minor premise and the conclusion are categorical proposition.

Example If Ms. Lopez cheat, she will fail

- Major premise

Ms. Lopez cheated

- Minor premise

 _________________________ Therefore, she failed.

- Conlusion

Conditional Syllogism Rules 1. Posit the antecedent, posit the consequent (Modus Ponens) 2. Negate the consequent, negate the antecedent (Modus Tollens) 3. Posit the consequent, no conclusion 4. Negate the antecedent, no conclusion

The Positing Process a. A Ↄ B A  _______ B

b. A Ↄ -B A _______ -B

c. -A Ↄ B -A  ________ B

d. -A Ↄ -B -A ________ -B

The Negating Process a. A Ↄ B -B  _______ -A

b. A Ↄ -B B _______ -A

c. -A Ↄ B -B  ________ A

d. -A Ↄ -B B ________ A

Examples If Mr. Capilayan is a monsters, then he has fangs. Mr. Capilayan does not have fangs.  _______________________________________ Therefore, Mr. Capilayan is not a monster

Disjunctive Syllogism •

Is one whose major premise is a disjunctive proposition consisting of alternatives, while the minor premise affirms or denies any of the disjuncts, and the conclusion merely follows from its affirmation or denial.

Complete disjunction •

•

Whose parts are mutually exlusive, that is, they contradict each other. Rules

1. Posit one alternative, negate the other (Ponendo-tollens) 2. Negate one alternative, posit the other. (Tollendo-ponens)

Incomplete Disjunction •

Whose parts are not mutually exclusive, that is they do not contradict each other.

Rules: 1. Posit one alternative, negate the other 2. Negate one alternative, no conclusion

Conjuctive Syllogism •

Rules

•

Posit one alternative, negate the other

•

Negate on alternative, no conclusion.