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Rule 1Rule 1

y The syllogism must contain 3 TERMS

only.

y Example:

All Paulinians are honest.

Peter is a Paulinian.

Therefore, Peter is honest.

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Violation of Rule 1:Violation of Rule 1:

y Fallacy of Equivocation (4 terms)

y Example:

All men are rational.

Rowena is not a man.

Therefore, Rowena is not rational.

MEN in the major premise isunderstood as human beings; in theminor premise, it is understood asmale. So, INVALID.

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Rule 2Rule 2

y The middle term must be UNIVERSAL

at least once in the premises.

y This is to ensure that the middle term

is able to establish a connection

between the minor and the major

terms in the conclusion.

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Rule 2Rule 2

y Example:

yAll vitamins are good for the body.

y

Ascorbic acid is a vitamin.y Therefore, ascorbic acid is good for

the body.

y Mu + Pp

y Su + Mp

y Su + Pp - valid

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Violation of Rule 2:Violation of Rule 2:

y Fallacy of undistributed middle:

y This happens when the middle term is

never universal in the premises.

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Violation of Rule 2Violation of Rule 2

y Example:

yAll cats are animals.

y

All dogs are animals.y Therefore, all dogs are cats.

y Pu + Mp

y Su + Mp

y Su + Pp invalid: undistributed middle

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Rule 3Rule 3

y The terms in the conclusion cannot be

universal if they are particular in the

premises.

y The rule emphasizes the fact that the

extension of these terms cannot be

LARGER than those in the premises.

y If they are particular in the premises,they must also be particular in the

conclusion.

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Violation of Rule 3:Violation of Rule 3:

y Illicit minor:

y The minor term is particular in the

premise, but becomes universal in the

conclusion.

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Violation of Rule 3Violation of Rule 3

y Illicit minor

y Example:

y

All drivers are not maids.y Some drivers are honest people.

y Therefore, All honest people are not

maids.

y Mu Pu

y Mp + Sp

y Su Pu - invalid

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Violation of Rule 3Violation of Rule 3

y Illicit major

y The major term is particular in the

premise, but becomes universal in the

conclusion

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Violation of Rule 3Violation of Rule 3

y Illicit major

y Example:

y

All exercises are good for the body.yAll food are not exercises.

y Therefore, all food are not good for the

body.

y Mu +Pp

y Su Mu

y Su Pu - invalid

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Violation of Rule 4Violation of Rule 4

y Misplaced middle term

y The middle term is in the conclusion.

y Example:

yAll men are rational.

y The pope is a man.

y Therefore, the pope is rational and a

man.

invalid!

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Rule 5Rule 5

y When the two premises are

affirmative, the conclusion must be

affirmative.

y Example:

yAll soldiers are brave.

y Gen. Apollo is a soldier.

y Therefore, Gen. Apollo is brave.

Mood: AAA

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Violation of Rule 5Violation of Rule 5

y Negative conclusion

y The two premises are affirmative, but

the conclusion is negative.

y Example:

yAll houses are buildings.

yAll churches are buildings.

y Therefore, all churches are not

houses.

y Mood: AAE invalid!

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Rule 6Rule 6

y From 2 negative premises, no

conclusion can be drawn.

y Violation committed is NEGATIVE or

EXCLUSIVE PREMISES

y Example:

yAll men are not plants.

yAll plants are not cars.

y Therefore, all cars are not men.

y Mood: EEE - invalid

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Rule 7Rule 7

y From 2 particular premises, no

conclusion can be drawn.

y Violation committed: PARTICULAR

PREMISES

y Example:

y Some Filipinas are beautiful.

y Some Filipinas are maids.

y Therefore, some maids are beautiful.

y Mood: III - invalid

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Rule 8Rule 8y If one premise is negative, the

conclusion must be negative.

y If one premise is particular, the

conclusion must be particular.y Reason: the conclusion follows the

weaker premise.

y

The Particular is weaker than theuniversal;

y The negative is weaker than the

affirmative.

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Rule 8Rule 8

y Example:

yAll trees are plants.

y Some trees are useful things.

y Therefore, some useful things are

plants.

y Mood: AII - valid

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Violation of Rule 8Violation of Rule 8

y Invalid mood

y Example:

yAll saints are holy.

y Some saints are women.

y Therefore, all women are holy.

yAIA, Invalid mood!

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Violation of Rule 8Violation of Rule 8

y Invalid mood

y Example:

y Some mayors are honest.

yAll mayors are not governors.

y Therefore, all governors are not

honest.

y Mood: IEE, invalid

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Violation of Rule 8Violation of Rule 8

y Invalid mood

y Example:

y Some mayors are honest.

yAll mayors are not governors.

y Therefore, all governors are honest.

y Mood: IEA, invalid

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Violation of Rule 8Violation of Rule 8

y Invalid mood

y Example:

y Some mayors are honest.

yAll mayors are not governors.

y Therefore, some governors are

honest.

y Mood: IEI, invalid

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Thanks!Thanks!--sergeserge