1. Syllogisms
A Lecture

2. SYLLOGISMS

6. The conclusion is always used to
identify the terms of the syllogism.

7. Example:

8. VALID CATEGORICAL SYLLOGISMS

9. INVALID CATEGORICAL SYLLOGISMS:

10. • “If-then” syllogism
• The minor premise must either affirm the
antecedent or deny the consequent.
• If the minor premise affirms the antecedent
the conclusion must affirm the consequent.
• If the minor premise denies the consequent
the conclusion must deny the antecedent.

14. VALID CONDITIONAL SYLLOGISM:

15. INVALID CONDITIONAL SYLLOGISM:

16. Ex. Ex.
If you go to school, you will If you go to school, you will
learn something learn something
You do not go to school You learn something
You will not learn anything You go to school
(Not necessarily! One may (Again, one may learn
learn out of school) elsewhere)