Cri2101 Bb Lesson Three

7/24/2019 Cri2101 Bb Lesson Three

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GOOD , VALID , STRONG ARGUMENTS

What is a GoodArgument?

What is a VaidArgument?What is a StrongArgument?

What are the Tests!or an Argument to "e Good?

W#AT IS A GOOD ARGUMENT ?1$ Good reason to believe = PLAUSIBLE PREMISES

2. The Conl!sion "ollo#s "ro$ the%re$ises

A %LAIM IS &LAUSI'LE i" #e have good reasonto believe it is tr!e.

A lai$ is LESS &LAUSI'LE i" #e haveess reason to believe it is

tr!e. A lai$ is IM&LAUSI'LE (

DU'IOUS i" #e have no reasonto believe it is tr!e.

&EA%%E&T A %LAIM i" #e 'no# it is tr!e "ro$ o!r o)n e*+eriene.

&ERE-E%T A %LAIM i" #e 'no# it is "alse "ro$ o!ro)n e*+eriene$

E*e+t i! .

1. &e have (ood reason to do!bt o!r $e$or) .

2. The lai$ ontradits other e*%erienes o" o!rs .+. There is a (ood ar(!$ent abo!t the lai$.

B!t too o"ten , #e re$e$ber #hat #eDEDU%ED !rom our e*+eriene ,

and not #hat #eA%TUALL/ e*+eriened$E.(. This is )hat Tom sa) . A shabbil)-dressed )o!th in an e$%t)

lassroo$ #ho s%otted a %!rse on a table. The )o!th loo'ed shi"til) aro!nd

hi$. The ne*t $o$ent, the )o!th #as (one and so #as the %!rse.

This is )hat Tom sa0s . That )o!th stole the %!rse. I sa# hi$

do it. e #as in the lassroo$ and he s%otted a %!rse on the table. e

loo'ed aro!nd %rett) shi"til) and tho!(ht he o!ld (et a#a) #ith ta'in( the

%!rse. So he (rabbed it and #ent.

1. o# does To$ 'no# the )o!th tho!(ht that he o!ld (et a#a) #ith it/

Tom is 1ustma2ing u+ a stor0$


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2. o# does To$ 'no# the )o!th (rabbed the %!rse/ Tom didn3tsee

him dothat 45$ &hat $a'es To$ sa) the )o!th loo'ed aro!nd shi"til) as i" to steal the

%!rse/ &erha+s the 0outh reogni6ed that the +urse "eonged

to his gir!riend ( sister, and oo2ed around !or her$ When he

didn3t see her, he deided to ta2e it !or her$

To$ S#OULD NOT #AVE DEDU%ED ( IN7ERRED 7ROM #IS

&REVIOUS 8NOWLEDGE (E9&ERIEN%Eo" so$e thie" loo'in( aro!nd

0!i'l) and stealin( a %!rse. To$ S#OULD NOT #AVE %OME TO T#E %ON%LUSIONthat the )o!th is

the thie".

Instead, To$ S#OULD #AVE DISTINGUIS#ED W#AT #E #AD SEEN

7ROM W#AT #E #AD DEDU%ED ( IN7ERRED$ nl) then #o!ld To$ have realied that #E #AS NO GOOD ARGUMENT

to $a'e the onl!sion he $ade.

SO, W#AT MA8ES A GOOD ARGUMENT?

Is it an ar(!$ent that onvines the listener/

&hat i" Ann is in a bad $ood, and nothin( )o! sa) #o!ld onvine her/

&hat i" 3i$$) is dr!n' and )o! an4t onvine hi$ not to drive hi$sel"

ho$e/ 5oes it $ean )o!r ar(!$ent is bad/

6Consider the "ollo#in( ar(!$ents.

All books are written by women. So the author of this book is a woman.

7alse Pre$ise So 7alse

Conl!sion 89o (ood reason to believe :

'AD ARGUMENT

All books are written by women. So the author of this book is a human being.

7alse Pre$ise Conl!sion does not

"ollo# "ro$ the %re$ise 8 9o (ood reason to believe :


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'AD ARGUMENT

All books are written by humans. So the author of this book is either a man or

a woman.

Pla!sible Pre$ise Conl!sion "ollo#s "ro$

the %re$ise 8 Good reason to believe :

GOOD ARGUMENT

Dr. E teaches Critical Analysis. So Dr. E is bald.

Good ; Bad ar(!$ent/ &h)/

Dr. E is very critical in his assessment of everything. So he is qualified to teach

critical analysis.

Good ; Bad ar(!$ent/ &h)/

E9AM&LES O7 A 'AD ARGUMENT

:;


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%ONDITION7R A >ALI5 ARGUME9T ?

I! the +remises are true, the onusion aso has to "e true$There is no %ossible #a) "or the %re$ises to be tr!e and the onl!sion

"alse.

Dr. E is very analytical. So he is good at teaching Critical Analysis. VALID

ARGUMENT

Dr. E is very analytical. So he is bald. INVALID ARGUMENT

A >alid Ar(!$ent an be a GOOD ( 'AD ARGUMENT.

Every college student has to $ay fees. Su%y is a college student. So Su%y hasto $ay fees. VALID GOOD ARGUMENT

I" Pre$ises tr!e, then Pre$ises %la!sible

Conl!sion $!st also be tr!e. Conl!sion "ollo#s "ro$ the

%re$ises.

Every elected official in &alaysia is less than '( years old. So the )rime

&inister of &alaysia is less than '( years old. VALID 'AD

ARGUMENT

I" Pre$ise tr!e, thenConl!sion $!st also be tr!e.

Pre$ise not

%la!sible ;

5!bio!s %re$ise

Are these VALID Arguments?1. So$e Gree's are lo(iians. There"ore, so$e lo(iians are Gree's.2. All Gree's are h!$an, and all h!$ans are $ortal. There"ore, all

Gree's are $ortal.+. So$e Gree's are lo(iians, and so$e lo(iians are tireso$e.

There"ore, so$e Gree's are tireso$e.


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@. Either #e are all doo$ed or #e are all saved. &e are not all saved.

There"ore, #e are all doo$ed.. So$e $en are ha#'ers. So$e ha#'ers are rih. There"ore, so$e $en

are rih.Ans)ers . 1 >alid 2 >alid + Invalid @ >alid

Invalid

9o. +? Some Gree2s are ogiians, and some ogiians are

tiresome$ There!ore, some Gree2s are tiresome$ INVALID

So$e Gree's are lo(iians

So$e lo(iians are tireso$e.

There"ore, so$e Gree's are tireso$e

9o. ? Some men are ha)2ers$ Some ha)2ers are rih$ There!ore, some

men are rih$ INVALID

So$e $en are ha#'ers

So$e ha#'ers

are rih

There!ore, some men are

rih$ INVALID

TIRESMEGREE8S

LOGI%IANS

MEN #AW8ERSRI%#


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B 8ii: INVALI

D

I" P, then .

9ot P,

So not .

P : diamond Q : cut

glass

I" an ob6et is dia$ond, then it an

!t (lass.

A is not a dia$ond.

So A annot !t (lass.

C 8i: VALID I" P, then .

P is tr!e,

So is also tr!e.

P : diamond Q : cut

glass


!t (lass.

A is a dia$ond.

So A an !t (lass.

C 8ii:INVALI

D

I" P, then .

is tr!e,

So P is also tr!e.


!t (lass.

A an !t (lass.

So A is a dia$ond.

W#AT IS A STRONG ARGUMENT ?

Belo# is the &RO%ESSinvolved in ANAL/ING W#ET#ER T#E

%ON%LUSION 7OLLOWS 7ROMT#E &REMISESo" an ar(!$ent ?

;$ Be reative and i$a(ine ever) %re$ise PSSIBLE.=$ Consider eah o" the %re$ises.

5$ o#TRUEis eah %re$ise/F$ In an) #a), is the onl!sion 7ALSE/

NO VALID ARGUMENT /ES INVALID ARGUMENT

Ever) #a) the %re$ises o# li'el) is the %re$ise;s "alse/

o!ld be tr!e,


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the onl!sion is tr!e. VER/ UNLI8EL/ NOT SOUNLI8EL/

= STRONG =

WEA8

ARGUMENTARGUMENT

< Ever) GOODar(!$ent is VALID ( STRONG. < 9ot ever) VALID ( STRONGar(!$ent is GOOD.

8 bea!se a %re$ise o!ld be i$%la!sible : < nl) INVALIDar(!$ents are lassied "ro$

STRONG TO WEA8. < Ever) WEA8ar(!$ent is 'AD.

VALIDIINVALID

STRONG

IWEA8

'AD

T#REE INDE&ENDENT TESTS !or an argument to "e

GOOD

1. The PREMISES are %la!sible.2. The PREMISES are $ore %la!sible than the Conl!sion.+. The ARGUME9T IS valid ; stron(.

DI Consider the "ollo#in( onversation bet#een A and C.

A and B are housemates, renting a house together.C is their friend.

A and C have just come bac to A!s house from a late-night movie.B is not in the house.

C ? *ou didn#t have any eggs in the house this morning+ did you!

A ? ,o+ why!

C ? -ell+ you#ve got some in the fridge now.


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A ? " must have bought the eggs+ since she knew was out and wouldn#t be

back till late at night.

A3s ARGUMENT .B;C %onusion ' must ha@e "ought the eggs$B=C &remise B;C She 2ne) I )as out and )oudn3t "e "a2

ti ate at night$

A3s argument is NOT VALID$E@en though the +remise is true, the onusion is not neessari0

true "eause '3s mother ( !riend ( andord

oud ha@e "rought o@er the eggs and +aed them in the !ridge

)hen the0 )ere out$#ene, there are SO MAN/ LI8EL/ &OSSI'ILITIES !or the +remise

to "e true and the %onusion !ase that ma2es A3s argument aWEA8 ARGUMENT$

DII Let !s reonsider the onversation bet#een A and C.

C ? *ou didn#t have any eggs in the house this morning+ did you!A ? ,o+ why!

C ? -ell+ you#ve got some in the fridge now.

A ? " must have bought the eggs+ since she knew was out and wouldn#t be


C ? Are you sure!

A ? Sure. ,o one has a key to my house exce$t ". And she didn#t $lan to have

any guests over today.

A3s ARGUMENT .B;C %onusion ' must ha@e "ought the eggs$B=C &remises B5C She 2ne) I )as out and )oudn3t "e

"a2 ti ate at night$ No one has a 2e0 to m0 house e*e+t '$ She didn3t +an to ha@e an0 guests o@er

toda0$ B im+0ing no


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one ese oud ha@e "een in the house

e*e+t '$C

A3s argument isSTRONGER no) "eause SOME O7 T#E &OSSI'LE

WA/S the &remises

oud "e true and the %onusion !ase #AVE 'EEN RULED OUT "0ha@ing more +remises$

'ut it is STILL NOT A VER/ STRONG ARGUMENT$

DIII 9o# onsider a "!rther onversation bet#een A and C.

C ? *ou didn#t have any eggs in the house this morning+ did you!

A ? ,o+ why!

C ? -ell+ you#ve got some in the fridge now.A ? " must have bought the eggs+ since she knew was out and wouldn#t be


C ? Are you sure!

A ? Sure. ,o one has a key to my house exce$t ". And we never let anyone

else in.

C ? "ut didn#t your neighbor &rs. / say she had some eggs from her son#s

farm!

A ? *es+ but " said we should only bring food into the house that we had

$urchased ourselves at the health0food store. And she always kee$s her word.

A3s ARGUMENT .B;C %onusion ' must ha@e "ought the eggs$B=C &remises BHC She 2ne) I )as out and )oudn3t "e "a2

ti ate at night$ No one has a 2e0 to m0 house e*e+t '$ We ne@er et an0one ese in$ ' said )e shoud on0 "ring !ood into the

house that )e had

+urhased ourse@es at the heath!oodstore$ ' a)a0s 2ee+s her )ord$

A3s argument is A LOT STRONGER no) "eause SO MAN/ O7

T#E WA/S in )hih the


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&remises oud "e true and the %onusion !ase #AVE 'EEN

RULED OUT$

STILL, T#E ARGUMENT IS NOT VALID "eause the andord oud

ha@e gotten a o2smith

to o+en the door, and +ut the eggs in the !ridge ( a "urgaroud ha@e "ro2en in and e!t

the eggs "ehind ( ' oud ha@e "ought a hi2en and e!t it in

the !ridge and it aid eggsthere ( ET%$

T#ESE ARE &OSSI'LE WA/S that the &remises oud "e true and

the %onusion !ase4 'UT T#E/ ARE ALL SO UNLI8EL/$ So the argument is STRONG$

E9ER%ISE . Eval!ate the "ollo#in( ar(!$ent.

&r. 1an has been teaching for 23 years.

So he is a good teacher.

&r. 1an has been teaching for 23 years.

So he is a good teacher.


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&hih lai$ is the %ON%LUSION/

&hih lai$ is the &REMISE/

Is the %re$ise %la!sible/ Fes ; 9o

5oes the onl!sion "ollo# "ro$ the %re$ise/ Fes ; 9o

1. So, is it a GOOD ARGUMENT/ Fes ; 9o&F /

2. I" it is tr!e that Mr. Tan has been teahin( "or 2 )ears,is it ALSO TRUEthat he is a (ood teaher/ Fes ; 9o

So, bea!se there are other riteria 8 %re$ises : "or bein( a (ood teaher,is it a VALID ARGUMENT/ Fes ; 9o

Is it an INVALIDARGUMENT/ Fes ; 9o

+. List as $an) riteria 8 %re$ises : as )o! an that Mr. Tan $!st have to be

a (ood teaher.

So, #hat is the &OSSI'ILIT/ ( %ERTAINT/o" Mr. Tan bein( a (oodteaher 6!st bea!se he

has been teahin( "or 2 )ears/ H ; J hane

So, is it a STRONG ( WEA8 ARGUMENT/

@. 9o# re%air the ar(!$ent to $a'e it a GOOD ( STRONG ARGUMENT.


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. Eval!ate the "ollo#in( ar(!$ent )o!rsel". Good/ >alid/ Stron(/

" loced the o#ce and left for lunch at $.%%pm. &n m' wa' to the

cafeteria, " saw the gardener. (e was mowing the lawn near m' o#ce.)here was no one else around. *hen " returned at +.%%pm and unloced

the door, " was shoced to discover m' drawer broen into, and %%

dollars gone )he gardener must have taen it

Good ar(!$ent/ &h) ; #h) not/

>alid ar(!$ent/ &h) ; #h) not/

Stron( ar(!$ent/ &h) ; #h) not/

"renechin""CP+%$

Cri2101 Bb Lesson Three

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Transcript of Cri2101 Bb Lesson Three