03-analyzing arguments-basics ver nov 2011
TRANSCRIPT
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Argumentation
Top ic 3
Par
t 1 of2
The
Basics
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Quotes to Ponder
Much that is taught in collegeclasses grows soon out of date,
but the skills of correct reasoning
never become obsolete.
- Irving M. Copi& Carl Cohen
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Do you find hisargumentconvincing?
Why Not?
Hey!! Folks!!ALLsmartpeople drinkXXX!!
I drinkXXXall the time!!I am a smartperson!!
So, do you drinkXXX??
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What is an
Argument
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Argument? Yes&
No.
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Analyzing Arguments
Hisconditionhas gotten
worsesince webled him.
Oh no,well
have tobleedhim
again.
Teenpregnancyis up this
year.
We
need toget rid ofthose sexeducation
classes!You designed
the site, its clearlyyour fault!
I havent sold
a single ice watersnorkeling kit onmy site.
Are You Convinced?Why Not?
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Analyzing Arguments
ArgumentA claim put forward& defendedwithreasons.
Statement / ClaimA sentence that can sensibly be
regardedas eithertrue/false.
Definitions ofImportant Terms:
truefalse
TruthValue
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Examples ofStatements / Claims:
~Redis a color.
~Kuala Lumpuris in Singapore.
~Ghosts do exist.
~Titanicis a bettermovie than Star Wars.
or Youve got tobeJOKING!!
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Statementsare eitherpremisesorconclusions, depending on their
role in an argument.Premises
Statementswhichare used to supportotherstatements.
Conclusion
Statements whichare supportedbyotherstatements.
Crucial elementthatmakesa group ofstatements anargumentis an inference.Aninferenceis supposed to establish
the truth ofconcluding statement.
inference
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Arguments composed of
Analyzing Arguments
Premise (s)
Ar
gum
ent
Premise (s)Statementsclaimedtoprovide evidenceforanother statement, theconclusion.
ConclusionStatementthat thepremises
are claimed to prove/support.
Conclusion
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Three things aboutstatements:
1. 2. 3.
1. A sentence may be used to expressmore than one statement.
Example,
Roses are red& violets are blue.
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2. Notall sentences are statements.
Examples,Where is yourhouse?(Question)
Close yourbook!(Command)
Please submityourassignment.(Request)
Let us study tonight.(Proposal)
InsertyourID into the column.(Instruction)
Oh, my goodness!(Exclamation)
Nonstatements
truefalse
Truth
ValueNonstatementshaveNO
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Some sentences look likenonstatements,are actuallystatements & can be used in
arguments. Here are two examples:
Rhetorical Question
Ought Imperative
Alyssa, you should quit smoking. Dont you
realize how bad that is for your health?
Commencement address: Do not read beautymagazines. They will only make you feel ugly.
(Mary Schmich)
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Exclusions to nonstatements
RhetoricalQuestions OughtImperative&
Rhetorical QuestionsLooks like a questionbutactuallyassertions ofgood/bad.
E.g. Andy, you should quit smoking. Dontyou realize how bad it is for your health?
Assertions something stronglybelieved
statements
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Ought ImperativeLooks like a commandbut actuallyassertions.
E.g. Do not read beauty magazines.They will only make you feel ugly.
(You oughtorshouldnot read.)
Exclusions to nonstatements
RhetoricalQuestions OughtImperative&
statements
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3. Considercontextin which theparticular expression is used.
Example,
Dont cry.might becommandin onecontext&ought imperativein another
context.
Dontcry.
Dontcry.
command ought imperative
Ought imperative: intended to assert a value orought judgmentabout what is good/bador
right/wrong.
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Premises&
conclusions
A
rgu
me
nt
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Premise Conclusion
Put forward as atruth, but whichis not proven.
It is hot in here.
This is a verybeautiful car.
People of this
town are angry.
Statement you wantothers to agree.
Drawnfrompremise (s).
Examples,We need to get out.
You should buy thisbeautiful car.
The factory should be
built elsewhere.
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IdentifyingPremises&Conclusions
Since, for, seeing that,
in view of the fact that,because, given that, as,
as indicated by.
E.g. I would not agreewith you seeing thatyou have made thedecision without my
concern.
Therefore, it follows
that, wherefore, as aresult, suggests that,
thus, consequently, for
this reason, so, whichshows that, that is why,accordingly, we may
infer that, implies that,
hence, proves that.
PremiseIndicators ConclusionIndicators
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IdentifyingPremises &Conclusions
However, beware of these examples!!
I havent seen you sincelast year.
I wouldnt mindseeing thatmovie again.
Sometimes there is no indicator.E.g. Cats are smarter than dogs.
You cant get 8 cats to pull a sled through snow.
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I havent seen you since high school.
Thusfar everything has been great.
It was so cold that even the
ski resorts shut down.There is water on the floorbecause
the sink overflowed.
In noneof these examplesdoes the term in red
function as an indicator word.
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Exercises
2.1 Statement/Non-Statement.
2.2 Identifypremises&
conclusions.
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1. Capital punishment is wrong.
2. Can vegetarians eat animal crackers?3. Ali is the greatest striker in football history.
4. What do you say we stop at the next stop?
5. Lee was the first prime minister of Singapore.
6. Lets party!
7. Great!8. Keep off the grass. (sign)
9. If Sally calls, tell her Im at the library.
10. I hope Peter likes his new job.
2.1 Statement/Non-Statement.
Statement
Non-Statement
Statement
Non-Statement
Statement
Non-Statement
Statement
Non-Statement
Non-Statement
Statement
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2.2 Identifypremises&conclusions.
1. Since light takes time to reach our
eyes, all that we see really existed inthe past.
2. Life changes when you least expect itto. The future is uncertain. So seizethis day, seize this moment, & makethe most of it.
3. Take care of a good name: for thisshall continue with thee, more than a
thousand treasures precious & great.
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2.2 Identifypremises&conclusions.3. There is no definitive way to prove any one set of
religious beliefs to the exclusion of all others.For that reason religious freedom is a human right.
4. Science is based on experiment, on a willingness to
challenge old dogma, on an openness to see theuniverse as it really is. Accordingly, sciencesometimes requires courageat the very least thecourage to question the conventional wisdom.
5. Do not play your sound system loudly as you maynot be able to hear warning sirens from emergencyvehicles. In addition, hearing damage from loud
noise is almost undetectable until its too late.
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Class Activity
Make yourownstatements & arguments.
Askother studentsto identifythepremise (s)& the conclusion.
premise conclusion
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2 Types of Arguments
SimpleHas only a single conclusion.
Nosub conclusions.
ComplexContain at least1 sub conclusionto support a single main conclusion.
E.g. This is a beautiful car.You should buy this car.
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2 Types of Arguments
Example of acomplexargument,
We know thateitherA orB committedthe robbery.
ButAcouldnt have committed therobbery because he was in prisonwhen the robbery was committed.
Therefore, B committed the robbery.
Mr. A Mr. B
Robber!!
sub
conclusion
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What is NOTan Argument?
2 conditionsforArguments:
1. A group of2 ormorestatements
&
2. One of those statements
(conclusion) is claimedorintendedto beprovedor
supportedbyothers (premises).
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What is NOTan Argument?
5 Types:1. Reports
2. Unsupported statementsofbelieforopinion
3. Conditional statements
4. Illustrations
5. Explanations
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What is NOTan Argument?
REPORT
Name: Susan
Birth: 20 / 06 / 80
Hometown: Muar
Hobby: ReadingAmbition: Doctor
E.g. Susan was born in 1980,in Malaysia. She grew up in
a small town, Muar & .
To conveyinformationabout a subject, not tooffer reasons why onestatement should be
accepted on basis of others.
Reports
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What is NOTan Argument?
Example (1/2),
Belief: I believe in God.God is the One who created us& we will return to Him
once we die.
Unsupported statements ofbelieforopinion
orAssertion
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Example (2/2),
Opinion: People are not free. Those
who think they are free are hopelesslynave. People are no more able to controltheir own destinies than are ants,& its just anti-scientific to say so.
What is NOTan Argument?
Unsupported statements ofbelieforopinion
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What is NOTan Argument?
Examples,
Ifit rains, thenthe picnic
will be cancelled.You must speak French
if you grew up in Quebec.
Bonjour!!
Conditional Statementsif-thenstatements
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What is NOTan Argument?
Intended to provide examples of a claimrather than toprove orsupportclaim.
Illustrations
Examples,
Many children like to engage in privatespeech. E.g.3 year-old Susan sometimestalk to herself when she plays with her doll.
Illustration: People are not free;just look athow many abusers were abused as a child.
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What is NOTan Argument?
Try to showsomething is the case,notto prove it is the case.
Explanations
I fell down because thefloorwas slippery
( E x p l a n a t i o n ) . v e r s u s
Example,
Capital punishment should be abolishedbecauseinnocent people may be
mistakenly executed(Argument).
Arguments or
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I speak English because my parents sent meto a boarding school in Kuala Lumpur.
If Ali comes to the party, then Alice will cometo the party.
Explanation
Conditional Statement
Earth was much drier in the distant past
than it is now, & there were large deserts ininland areas. There were no flowering plantsthey evolved much later. The most commontrees were conifers.
Report
Exercise: Arguments orNon arguments
Arguments or
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How can you say that Manchester United is abetter football team than Chelsea? Wake up you
fool! No current English football team is ever betterthan Chelsea, not even Liverpool in the 70s! a fan
The smart school program deserves to besupported with more money. Not only does this
program develop the talents of our students, it alsoleads to more hard-working students. Furthermore,at current funding levels the program cannot beimplemented in many schools. a school teacher
Unsupported statement of belief or opinion
An argument
Exercise: Arguments orNon arguments
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Exercise 2.4
D e t e r m i n e w h i c h o f t h e
f o l l o w i n g p a s s a g e sc o n t a i n arguments & w h i c h do not .
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Evaluating Arguments
To evaluate arguments,ask 2 questions:
1. Are thepremises true?
2. Can thepremisesprovide
good reasonsfor itsconclusion?
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Are thepremises true?
Canpremisesprovidegood reasonsfor its conclusion?
Evaluating Arguments
Evidence
Principle of
RationalAcceptance
Deductivearguments
Inductivearguments
Overview
A P i T ?
To evaluate
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Are the Premises True?
To evaluate, ask2 questions:
1. It is true if it is supportedbyevidence.
2. It uses the Principle ofRational Acceptance.
To evaluate
3 points
R i l A
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Principle ofRational Acceptance
1. The claim does not conflictwithpersonal experience &
observations.Be aware that sometimes
ourinterpretation of ourobservation& experience
is not accurate .
Point
l R i l A
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Principle ofRational Acceptance
2. Does the claim conflict withourbackground beliefs?
Background beliefs:network of conscious & unconsciousbeliefs we use as a framework.
Make sure our beliefs are accurate& well grounded. Never believe withoutsufficient evidence &never believe more
strongly than evidence warrants.
Point
i i l R ti l A t
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Principle ofRational Acceptance
3. Does a claim come froma crediblesource?
We should accept a claim onauthorityifit comes from a
credible source thatwe haveno good reason to doubt.
Point
i i l R ti l A t
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Principle ofRational Acceptance
1. Source is notgenuineexpertorauthority.
2. Source is speakingoutside the area ofhis experience.
Expert?
Good reasons to doubtthecredib i l i ty include:
P i i l R ti l A t
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Principle ofRational Acceptance
Good reasons to doubtthecredibilityinclude:
3. The source is biased/ hasmotive to lie ormislead.
4. Accuracyof the sourcespersonal observations orexperiences is doubtful.
P i i l R ti l A t
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Principle ofRational Acceptance
Good reasons to doubtthecredibilityinclude:
5. Source is a mediaor internet source thatis generallyunreliable.
6. Claim made by source is in itself,highly implausible/unlikely.
C h P i id
To evaluate
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Can thePremise provideGood Reasonsfor its Conclusions?
2 kinds ofarguments:
DeductiveInductive
All arguments are(categorically) either
Deductive or Inductive
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Deductivearguments try to
prove theirconclusionswith rigorous,
inescapable
logic.
Inductivearguments try to
showtheirconclusions areplausible or
likelygiventhe premise (s).
Deductive Inductive
D d ti I d ti t
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Deductive&Inductive argumentsAllmen are mortal. (premise)
Gandhi was a man. (premise)
Gandhi was mortal. (conclusion)
Deductive argument
Gandhi was Indian. (premise)
MostIndians love curry. (premise)
Gandhi possibly loved curry. (conclusion)
Inductive argument
D d ti A t (1/3)
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Deductive Arguments (1/3)
Attempt to showconclusionsmustbe truegiven thepremises asserted.
Allmammals have hair. Pet Xis a mammal.
Pet
X
Conclusion???
D d ti A t (2/3)
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Example,
1) Allhumans are not perfect.
Deductive Arguments (2/3)
Yourparents are humans.
Therefore, yourparents
are not perfect.(So love them without condition)
Ded cti e Arg ments (3/3)
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Deductive Arguments (3/3)
Example,2) If a studentlives in
Regal Park,then he is an MMU student.M
M
U The studentdoes live inRegal Park.
So, he is an MMU student.
Deductive Arguments
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Deductive Arguments
If hes rich, he willorderexpensive wine.
He ISrich.
So, he willorderexpensive wine.
Waiter!!!
Wine year1911 !!!
Inductive Arguments (1/2)
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Inductive Arguments (1/2)
Simplyclaimthatconclusionsare likelyorprobablegiventhepremises offered.
XYTherefore, it is likelythe next
Malaysian Prime Minister will be a man.
Every previous MalaysianPrime Minister has been a man.
Example,
Inductive Arguments (2/2)
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Inductive Arguments (2/2)
Everyrubyso far discoveredhas been red. So,probably
allrubies are red.
AllHarry Potter novels have
been good. Therefore, thenextHarry Potter novelwill
likely be good Key differences (1 2 3)
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Key differences (1,2,3)
Deductive InductiveIfpremises aretrue,then the conclusionmustbe true.
Ifpremises aretrue,then the conclusionis
probablytrue.Conclusion followsnecessarilyfrompremises.
Conclusion followsprobablyfrompremises.
Premisesprovideconclusiveevidencefortruth
of theconclusion.
Premisesprovide good(butnot conclusive)evidencefortruth
of the conclusion.
Key differences (4 5)
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Key differences (4,5)
Deductive Inductive
Impossible for ALL thepremisesto be true&conclusionfalse.
Unlikelythatthepremisesaretrue&conclusionfalse.
Logicallyinconsistentto assertthepremises&denytheconclusion
(if you accept thepremises, then you
mustaccept theconclusion.)
Although logicallyconsistentto assertthe
premises & denythe
conclusion,conclusion is
probablytrueifthe
premises are true.
Conclusion
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Conclusion
A good argumenthas the following:
1. Allthepremises aretrue.
2. Premises provide good reasons toacceptconclusion. Deductivelysound& inductivelycogentargument.
3. Meetstandardsofcritical thinkingdiscussed in Topic 1.Clarity,Precision,
Accuracy, etc
Ded cti e
*Valid: so constructed
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DeductiveArguments
Valid* Invalid
(ALL areunsound)
Sound** Unsound
InductiveArguments
Strong Weak
(ALL areuncogent)
Cogent*** Uncogent
**Sound: having no
defect,sensible, valid.***Cogent: convincingor believable because
it is clear.
that if premises arejointly asserted, theconclusion cannot be
denied withoutcontradiction.
Conclusion
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Conclusion
Good Argumentdoes NOTmean:
Agrees with my viewsPersuasive argumentWell-written orwell-spoken argument
Exercise
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Exercise
Deductive or Inductive?
Common Patterns of
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Common Patternsof
Deductive Reasoning
HypotheticalSyllogismCategoricalSyllogismArgumentbyEliminationArgumentbased on MathematicsArgumentfromDefinition
Hypothetical Syllogism
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HypotheticalSyllogism
Syllogism three-line-argumentthat consists ofexactly2 premises
& aconclusion.
Hypotheticalsyllogism syllogismthat contains at least1 hypothetical
or conditional (if-then) premise
Premise 1 (Major Premise)Premise 2 (Minor Premise)Conclusion
Hypothetical Syllogism
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If then
Logic - conditional elementin aproposition, as
Caesar conquered Gaul,
inIfCaesar conquered Gaul,
he was a great general.
Logic - second memberof aconditional proposition, as
Caesar was a great general
inIf Caesar conquered Gaul,he was a great general.
Conditional Statement / Premise
*Caesar was a great generalif he conquered Gaul.
Antecedent Consequent
Consequent Antecedent
HypotheticalSyllogism
Hypothetical Syllogism
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HypotheticalSyllogism
Example, (1) Modus PonensIfA , thenB.
A. Therefore, B.
IfI want to get the scholarship,
then Id better study hard.I do want to get the scholarship.
Therefore Id better study hard
(fromponere, to
affirm-affirmingtheantecedent)
Hypothetical Syllogism
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HypotheticalSyllogism
Example,
(2) Chain ArgumentChain arguments consists of3 conditional statements linked
together in the following way.
IfA, thenB. IfB, thenC.
Therefore, ifA, thenC.AB
BC
Hypothetical Syllogism
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Example,
(2) Chain Argument
IfI dont study hard now,
I will not pass the subject.IfI dont pass the subject,
Ill be under probation.Therefore, ifI dont study hard
now, Ill be under probation.
HypotheticalSyllogism
Hypothetical Syllogism
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HypotheticalSyllogism
Example, (3) Modus Tollens(Denying theconsequent)
IfA , thenB.NotB. Therefore, notA.
If were in FOSEE, then were inMelaka. Were notin Melaka.
Therefore were not in FOSEE
Hypothetical Syllogism
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HypotheticalSyllogism
Example, (4) Denying theAntecedent
If you are the one who sends thoseflowers, you are a lovely person.
You are notthe one whosends me those flowers.
IfA , thenB.
NotA. Therefore, notB.
Therefore, you are not a lovely person.
Notreliable!!
Hypothetical Syllogism
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HypotheticalSyllogism
Example,
(5) Affirming theConsequent
If it is a banana, it is afruit.
It is afruit.
IfA , thenB.
B. Therefore,A.
Notreliable!!
Therefore, it is a banana.
Categorical Syllogism (1/2)
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CategoricalSyllogism (1/2)
Three-line argumentin whicheach statement begins with thewordAll, SomeorNo.
Example (1/3),
Allwhalesaremammals.Allmammalsare animals.
So, allwhalesareanimals.
whale
gorilla
lion
cow
Categorical Syllogism (2/2)
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CategoricalSyllogism (2/2)
Example (2/3),Allbatsarenocturnal animals.Nosalamandersarenocturnal animals.
Nosalamandersarebats.
Example (3/3),
Notennis playersareshort.Someadultsareshort.
Some adults are not tennis players
Argument by Elimination
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Argumentby Elimination
Seeks to logicallyrule outvarious possibilitiesuntil onlyasingle possibilityremains.
Therefore she went to class
But Susan did notgo to the library.
EitherSusan went to the
libraryorshe went to class.Example,
Argument based on
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Argumentbased on
Mathematics
Example,
Lighttravels at a rate of186,000 miles per second.
The sun is more than 93 million
miles distant from the earth.Therefore, it takes more than
eight minutesfor the suns light
to reach the earth.
93
millionm
iles
Math
Argument from Definition
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Argument from Definition
The conclusion is presentedas being truebydefinition.
Therefore, he is a doctor.
Peter is apediatrician.
Example,Pediatrician=doctor
Common Patterns of
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Common Patterns ofInductive Reasoning
Six common patterns,
Inductive generalization
Predictive argument
Argument from authority
Causal argument Statistical argument
Argument from analogy
Inductive Generalization (1/2)
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Inductive Generalization (1/2)
An argumentin which a generalizationis claimedto beprobably truebased on information about somemembers
of aparticular class. All, most.
Example,
Ive met 4Japanese people, & theywere hardworking. Therefore,probably,
most Japanese people are hardworking
Konnichiwa!!!
Inductive Generalization (2/2)
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Example,
All dinosaur bones so far discoveredhave been more than 65 million years old.
Therefore,
probably
ALL dinosaur bonesare more than65 million years old.
Inductive Generalization (2/2)
Predictive Argument
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Predictive Argument
Ap red ic t ion that isdefended with reasons .
Therefore,probably,
she will come late today
Example,
Amyalways
come late to class.
Must
hurry!!!
Argument from Authority
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Argument from Authority
Asserts a claim & then supports claimby citing somepresumed authorityorwitnesswho has said claim is true.
Therefore,probablythereis
a ghoston the
23rdfloor
Example,
My friend told me thathe
saw a ghoston the 23rdfloor.
Causal Argument
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Causal Argument
Assertsordenies that something isthe cause of something else.
Examples,
I cant log in the MMLS.The serverisprobablydown.
Rashid isnt allergic to peanuts.I saw him eat a bag of peanutson the flight from Langkawi.
Statistical Argument
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Statistical Argument
Example,
70% ofMMU studentsdrive to the campus.
Rosie is an MMU student.Most probably, shedrives to the campus.
Rests on statisticalevidence.
Air-Rosie
Argument from Analogy
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Argument from Analogy
Conclusion is claimed todepend on analogy(a comparisonofsimilarity)
between 2 or more things.
Basic logical pattern: These things are
similarin such-and-such ways.Therefore, theyreprobablysimilarin somefurther way.
Analogy
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~Aliis a graduate ofMMU University,& he is bright, assertive &polite.
~Mayis a graduate ofMMU University,& she is bright, assertive, &polite.
~Venu is a graduate ofMMU University.~ Therefore, most likely(orprobably),
Venu is bright, assertive, &polite.
Example, Ali May Venu
a ogy
Deductive
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Deductive
Validity
Inductive Strength
versus
Deductive
*Valid: so constructedthat if premises are
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DeductiveArguments
Valid* Invalid
(ALL areunsound)
Sound** Unsound
InductiveArguments
Strong Weak
(ALL areuncogent)
Cogent*** Uncogent
**Sound: having no
defect,sensible, valid.***Cogent: convincingor believable because
it is clear.
that if premises arejointly asserted, theconclusion cannot be
denied withoutcontradiction.
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DeductiveValidity
Valid?Invalid?
Validdoes notmean true.Validmeans that the argument
is well reasoned
Deductive Validity
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Deductive Validity
Validdeductive argument:logical ly rel iable
deductive argument(The conclusion really doesfollow
necessarilyfrom thepremises).
Premises ConclusionLeads to
Deductive Validity
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3 conditions:1. Ifpremisesare true,
conclusionmust be true.
2. The conclusionfollowsnecessarilyfrom thepremises.
3. It is impossible to assertallthepremises as true & deny
the conclusion
Deductive Validity
Deductive Validity
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educt e a d ty
Valid arguments can:1. Have obviouslyfalsepremises,
&false conclusion.
Example,
Allsquares are circles.Allcircles are triangles.
Therefore all squares are triangles
squares
triangles
circles
Deductive Validity
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2. Havefalsepremises,& a trueconclusion.
y
Example,Allfruits are vegetables.Caulifloweris afruit.
Therefore, caulifloweris a vegetable . cauliflower
Deductive Validity
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3. Have truepremises,& trueconclusions.
Example,If youre reading this, you are alive.
y
Therefore, youre alive.Youre reading this.
Deductive Validity
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However, valid arguments
y
All truepremises
FalseConclusion
CANNOT
CANNOThaveALL true premises,
& afalseconclusion.
Deductive Validity
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Invaliddeductive argument:the conclusiondoes not follow
necessarilyfrom thepremises.
y
Denying theantecedent,Affirming theconsequent.
Examples,
Notreliable!!
Denying the Antecedent Notli bl !!
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Argument of following form isinvalid:IfAthenB.NotA, therefore, NotB.
If youre hit by a car when youre 6 then youll dieyoung. But you were nothit by a car when you
were 6. Thus, you willnotdie young.
Example,
or or or
reliable!!
(Of course, you could be hit by a train or apianoor
at any other age after six or die of other causes!!)
Affirming the Consequent
Notli bl !!
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Argument of following form isinvalid:IfAthenB,Btherefore,A.
(Of course, even though thepremises are true,I might be in Johor, or any other state in Malaysia.)
If I am in Melaka, then I am in Malaysia.I am in Malaysia, thus, I am in Melaka.
Examples A B
If the factory is polluting the riverthen we see an increase in fish deaths.
And fish deaths have increased.Thus, the factory is polluting the river. x
x
reliable!!
Deductive Validity
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CONCLUSION
Validdoesnt mean good
ortrue argument.Validmeans argument is
well-reasoned,has a logically reliable
pattern of reasoning
y
Deductive
*Valid: so constructedthat if premises are
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Arguments
Valid* Invalid
(ALL areunsound)
Sound** Unsound
InductiveArguments
Strong Weak
(ALL areuncogent)
Cogent*** Uncogent
**Sound: having no
defect,sensible, valid.***Cogent: convincingor believable because
it is clear.
f pjointly asserted, theconclusion cannot be
denied withoutcontradiction.
Deductive Validity
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Ifargument is valid+premisestrue
y
Invalid, or have at least1false
premise, orboth
(good argument).
(bad argument)
unsounddeductive argument
sounddeductive argument
Quotes to Ponder
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Validdeductive argumentsare like steel traps.Once a person walks into the
trap by accepting thepremises,
there is no escape; the
conclusion follows necessarily.- Kathleen
Dean Moore
Q
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Inductive Strength
Weak
Strong
Inductive Strength
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Strong inductive argument:conclusion followsprobably
from thepremises.
Example,
Most models are thin & slim.Susan is a model.
Probably, she is thin & slim.
g
Inductive Strength
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Weak Inductive argument:the conclusionis notprobably
true even if thepremises are true.Example,
All Malaysian PM has been a man.Therefore, probably, the next
Malaysian PM will be a woman
g
Inductive Strength
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Strong inductive argumentcan:1. havefalsepremises, & a
probablyfalse conclusion.2. have truepremises, & a
probablytrueconclusion.
3. havefalsepremises, & aprobablytrueconclusion.
Inductive Strength
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Strong inductive argumentCANNOT??
have truepremises, & a
probablyfalseconclusion.
DeductiveA t
*Valid: so constructedthat if premises arej i tl t d th
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Arguments
Valid* Invalid
(ALL areunsound)
Sound** Unsound
InductiveArguments
Strong Weak
(ALL areuncogent)
Cogent*** Uncogent
**Sound: having no
defect,sensible, valid.***Cogent: convincingor believable because
it is clear.
jointly asserted, theconclusion cannot be
denied withoutcontradiction.
Inductive Strength
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Strong inductive argument+true premises
(good argument)Weak, or has atleast 1false premise
or both
cogentargument
uncogentargument(bad argument)
Quotes to Ponder
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TheAimofArgument,or discussion,shouldnotbe victory,
butprogress.
- Joseph Joubert