This document defines and explains categorical syllogisms. It discusses the key elements of categorical syllogisms including premises, terms, and rules governing validity. Categorical syllogisms are logical arguments with three terms and two premises that lead to a conclusion. The major premise contains the major term, minor premise contains the minor term, and the conclusion is derived from the premises. There are rules regarding the terms, quality of propositions, and quantity of propositions that must be followed for a syllogism to be valid. Fallacies can occur if these rules are violated.

1. MEDIATE
INTERFERENCE/SYLLOGISMS

2. SYLLOGISM
Aristotle define syllogism as a
"prepositional expression in which for
certain things which have been laid
down (premises), something other
than what has been laid down follows
of necessity from being so
(conclusion).

3. CATEGORICAL SYLLOGISM
Is a syllogism in which the
propositions are all categorical. It
is complex logical unit made up of
terms and propositions.

4. STRUCTURAL ELEMENTS OF
CATEGORICAL SYLLOGISM
BASIC PROPOSITION IN A CATEGORICAL
SYLLOGISM
1. Major Premise - the premise which contains the
major term. Generally, this premise has greater
extension than other propositions of the syllogism.
2. Minor Syllogism - the premise which contains
the minor term. Usually, this is the second
proposition and is preceded by the conjunction but.
3. Conclusion - the last proposition which has
been necessarily derived from the premises.

5. BASIC TERMS IN A CATEGORICAL
SYLLOGISM
1. Major Term - it is the predicate of the
conclusion and is found in the major
premise. It is usually designated by "P"
which means the predicate of the
conclusion.
2. Minor Term - it is the subject of the
conclusion and is found in the minor
premise. It is usually designated by "S"
which the subject if the conclusion.
3. Middle Term – occurs in each of the
premises but not in the conclusion.

6. Examples:
 Every BPSC student is a human being -------
--- Major Premise
 Mylene is a BPSC student ---------- Minor
Premise
 Therefore, Mylene is a human being ---------
Conclusion

7. To indicate the different elements of the categorical
syllogism, the following figures are used:
The major term ----------
The minor term ----------
The middle term ---------
To illustrate it:
All monkeys are animals MP (major premise)
But all chimps are monkeys mp (minor premise)
Therefore, all chimps are animals C (conclusion)

8. RULES GOVERNING THE VALIDITY OF
CATEGORICAL SYLLOGISM
RULES OF TERMS
Rule No. 1.
There must only be three terms. No more, no
less.
Example:
All BCCnians are students.
But Jason is a student.
Therefore, Jason is a BCCnians.

9. FALLACIES COMMITTED ON THIS RULE
 FALLACY OF FOUR TERMS OR FIVE
TERMS
It is committed when there are more than three
terms which are evident in the syllogism.
Example:
Every man is a sinner.
But Pope John Paul is a man.
Therefore, the parish priest is a sinner.

10.  FALLACY OF EQUIVOCATION
It is committed when the term applied to one
proposition has a different meaning as applied to the
other proposition in the syllogism.
Example:
Every pen is an instrument for writing.
But a pen is an enclosure for pigs.
Therefore, every enclosure for pigs is an instrument for
writing.

11.  FALLACY OF AMPHIBOLY
It is omitted when there is the use of analogous
terms.
Example:
God is love.
But love is blind.
Therefore, God is blind.

12. Rule No. 2.
The major term cannot become universal in the
conclusion unless it is universal in the premise.
Example:
Every plant is a living thing.
Stones are not living things.
Therefore, stones are not plants.

13.  FALLACY OF ILLICIT MAJOR
Example:
All cats are mammals. – particular
But no dogs are cats.
Therefore, no dogs are mammals. – universal
FALLACY COMMITTED ON THIS RULE

14. Rule No. 3.
The minor term cannot become universal in the
conclusion unless it is universal in the premise.
Example:
All singers are musicians.
But every musician is an artist.
Therefore, all singers are artists.

15.  FALLACY OF ILLICIT MINOR
Example:
Every circle is round.
But every circle is a figure.
Therefore, every figure is round.
FALLACY COMMITTED ON THIS RULE

16. Rule No. 4
The middle term must not appear in the
conclusion.
FALLACY COMMITTED ON THIS
RULE
 FALLACY OF ILLICIT MIDDLE TERM
Example:
All cats are animals.
But no dogs are cats.
Therefore, no cats are mammals.

17. Rule No. 5
The middle term must be universal at least
once.
FALLACY COMMITTED ON THIS
RULE
 FALLACY OF UNDISTRIBUTED MIDDLE
TERM
Example:
The earth is a planet.
But the Mars is a planet.
Therefore, the Earth is Mars.

18. Rule No. 6
If both premises are affirmative, the conclusion
must also be affirmative.
FALLACY COMMITTED ON THIS RULE
 FALLACY ON NEGATIVE CONCLUSION
Example:
Labanos is not a fruit.
But all fruits are delicious.
Therefore, labanos is not delicious.
RULES ON THE QUALITY OF PROPOSITIONS

19. Rule No. 7
If one premise is affirmative and the other
premise is negative, the conclusion is negative.
FALLACY COMMITTED ON THIS
RULE
 FALLACY OF AFFIRMATIVE CONCLUSION
Example:
All Americans are not Asians.
But all Filipinos are Asians.
Therefore, all Filipinos are not Americans.

20. Rule No. 8
If both premises are negative, no conclusion
follows.
FALLACY COMMITTED ON THIS RULE
 FALLACY ON NEGATIVE PREMISES
Example:
Some insects are not flies.
But some insects are not grasshoppers.
Therefore, some grasshoppers are not flies.

21. Rule No. 9
At least one of the premises must be universal. If
both premises are particular, then no conclusion
follows.
FALLACY COMMITTED ON THIS RULE
 FALLACY OF UNIVERSAL CONCLUSION
Example:
Some insects are not grasshoppers.
But, all insects are small.
Therefore, all grasshoppers are small.
RULES ON THE QUANTITY OF
PROPOSITIONS

22. END OF
PRESENTATION

23. GROUP 1