LESSON 8 PART 2: Logic

8/18/2019 LESSON 8 PART 2: Logic

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#) he ma!or premise is the hypothetical proposition" while the minor premise is astraight orward actual statement

') he minor premise defnes the situation1) he basis o ,alidity is the ma!orminor premise2) 3 the ma!or premise a4rms the antecedent o the ma!or premise" then the argument

is ,alid

5) 3 the minor premise denies the antecedent o the ma!or premise" then the minorpremise is stating the negation o the antecedent

Types of Hypothetical Syllogism

1. Conditional Syllogism is a syllogism that contains a conditional proposition as the ma!orpremise and a minor premise that is categorical" a4rmingdenying one o the parts o thema!or premise

Note* # parts* Antecedent ($st); -onse6uent (#nd)

3llus $* (%irst -onditional)Antecedent * 3 signal 7' is raised in 0anila"-onse6uent * -lasses will be suspended

3llus #* (&econd -onditional)Antecedent * 3 3 am going to pass 8ogic"-onse6uent * 3 will ha,e to study harder

9ruth o the conse6uent is dependent on the ulfllment o the conditionstated in the antecedent; thus" when the antecedent is true" the conse6uent is also true

hus*$. 3 signal 7' is raised in 0anila then classes will be suspended ut signal 7' is raised in 0anila

-lasses were suspended.

#. 3 3 am going to pass 8ogic" 3 will ha,e to study harder ut 3 passed 8ogic

3 ha,e studied harder.

2 Types of Conditional Syllogism!. ure Conditional

composed entirely o conditional propositions

3llus. 3 the :& tigers are the champions" then they topped the:AA. 3 they topped the :AA" then they


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+

"#$ES*$. he antecedent o the conclusion is the antecedent in the

premise

#. he conse6uent o the conclusion is the conse6uent in thepremise'. he conclusion is also a conditional proposition

%. &i'ed Hypothetical consists o a hypothetical proposition as the ma!or premise anda premise

(categorical) that a4rms or denies either the antecedent or theconse6uent the conclusion a4rmsdenies whiche,er is not used in the minorpremise

3llus. 3 you will study" then you will pass 8ogic. ?ou studied well.

hereore" you passed 8ogic.

3ts %orm is* 3 >

>

"ules in Validating a &i'ed Conditional Syllogism$. o accept the antecedent is to accept the conse6uent.#. o re!ect the conse6uent is to re!ect the antecedent.

T(o Valid )orms*$. A4rming the Antecedent (0@D:& @/&)

3 > 3 B > 3 B > B

> B > >

#. Denying the -onse6uent (0@D:& @88/&)

3 > 3 B > 3 B > B> BCB> B >

B B BCB

Note*


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$. %rom the truth o the antecedent" truth o the conse6uentollows.

#. %rom the alsity o the conse6uent" alsity o the antecedentollows.

T(o *nvalid )orms*

$. Denying the Antecedent #. A4rming the -onse6uent 3 > 3 > B >

B >

2. +is,unctive Syllogism a syllogism that contains a dis!unction (or an EeitherBorF statement) asthe ma!or premise and a premise which either a4rms or denies a dis!unct

Note* the parts are called dis!uncts; it could ha,e any order

3llus. 3t is either you pass or ail. ut you did not ail. hereore" you passed.

3ts %orm is* 3 or >ot >

"ules* (Dis!uncts cannot be both true or alse)$. 3 one part is true" the other part must be alse.

3 one is accepted in the minor premise" the other part must be

re!ected in the conclusion.#. 3 one part is alse" the other part must be true 3 one part is re!ected in the minor premise" the other part must

be accepted in the conclusion.

Valid )orms- !rming a +is,unct "e,ecting a +is,unct

$. 3t is neither nor not >3t is

3t is not EnotF >

$. 3t is either or >3t is not

3t is >


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#. 3t is neither not or >3t is not

3t is not >

#. 3t is either not or not >3t is EnotF not

3t is not >

'. 3t is neither not or not >

3t is not 3t is EnotF not >

/. Con,unctive Syllogism is a syllogism that epresses a !udgment that the two alternati,eassumptions cannot be true simultaneously. he parts are !oined by the word EandF. 3t consistso a denial o a con!unction in the frst premise and a premise which eithera4rmsdenies a con!unction.

"ules*$. %rom the truth o one part" ollows the alsity o the others;

#. %rom the alsity o one part" the truth o the other does not ollow.

Valid )orms-$. 3t is not both and

>ut >

ot

#. ot both and >ut

ot >

3llus $* he longest mountain range in the hilippines cannot be -ordillera and

agaytay at the same time

3t is the -ordillera

hereore" 3t is not agaytay

3llus #* he thing cannot be an amphibian and a reptile at the same time he thing is not an amphibian hereore" it is a reptile

ot both and >


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ot 3A83D

>

@r ot both and >ot > 3A83D

Summary of the Types of Hypotheticals

Conditional Con,unctive +is,unctive

$. AntecedentB -onse6uentB ot ,iceB,ersa

#. -onse6uentB %AntecedentB %ot ,iceB,ersa

$.$ -on!unctB @ther -on!unctB %

#.$ -on!unctB %

@ther -on!unctB %

$.$ Dis!unctB @ther Dis!unctB %

#.$ Dis!unctB %@ther Dis!unctB

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LESSON 8 PART 2: Logic