syllogistic figures

SYLLOGISTIC FIGURESFigure 1 (Sub – Pre)

M – T A dog is an animal. t – M But a puppy is a dog. t – T :. A puppy is an animal. Take note of the location of the M

Figure 2 (Pre – Pre)T – M Every man is a thinker. t – M But a fish is not a thinker. t – T :. A fish is not a man.

Note: focus on the location of the M

Figure 3 (Sub – Sub)M – T Some vegetables are cabbages.M – t But all vegetables are plants. t – T :. Some plants are cabbages.

Note: Where’s the M?

Figure 4 (Pre – Sub) T – M Some Filipinos are Igorots.M – t But all Igorots are God-created.t – T :. Some God-created beings are

Filipinos.

Again note the location of M

Principles of Categorical Syllogism

1. Principle of Reciprocal Identity Briefly expressed: A is B God is divine.

But C is B. But Jesus is divine.

:. A is C. :. God is Jesus.

2. The Principle of Reciprocal Non – IdentityBriefly expressed: A is B. All plants are living things.But c is not A. But stones are not plants. :. C is not B. :. Stones are not living

things.

3. The Principle of Dictum de Omni What is affirmed universally of a given term is affirmed of everything found within the extension of said term. For instance what is affirmed of the term “creature” can be affirmed of man, animals and plants which are extension ideas of the idea creature. If creatures are mortal then man, animals and plants are _______.

4. The Principle of Dictum de Nullo

Opposite of dictum de omni. What is negated universally of a given term is likewise negated of every term found within the extension of the said term.

If a plant is not a stone all extension ideas of the idea plant is not a stone.

5. The Principle of Contradiction If a THING IS, it cannot be IS

NOT at the same time. If this is a table, then it cannot be that this is not a table at the same time.

Basic Rules of Categorical Syllogism

1. There must be only three (3) univocal terms. 2. There can be no two (2) negative premises. 3. On quality, if the 2 premises are affirmative the conclusion is affirmative. 4. The conclusion is negative if one of the premises is negative. 5. The conclusion must be particular if one of the premises is particular.

6. In terms of quantity, there must be no 2 particular premises. One premise must be at least universal.

VALIDITY and TRUTH IN SYLLOGISM

Two Conditions: 1. Correct in form2. True in content.

◦A syllogism may be correct in form but false in content. Or may be incorrect in form but true in content. To be a valid categorical syllogism the form must be correct and the content must be true.