Introduction to critical thinking

1Aurora Computer Studies

Introduction to Critical Thinking

by Nalaka Gamage

Aurora Computer Studies(auoracs.lk)

http://www.auoracs.lk/

Aurora Computer Studies (auroracs.lk) 2

Agenda• What is critical thinking?• How to practice critical thinking?


What is critical thinking?


What is critical thinking?

• Critical thinking is the ability to think clearly and rationally about what to do or what to believe.


What is not critical thinking?

• Mere criticize everything• Thinking a lot

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What hinder critical thinking

• Lack of awareness/practice of rational (logical) thinkingo Those ignorant of how to think critically

• Personal biasnesso Some people deliberately avoid critical thinking on

situations where out come may put him in unfavorable situation

• Inherited opinion/Cultural biasnesso Most of the people die with the opinions they inherit from

parents and close oneso Example : More than 80% of those who born Islam will die

as Islam

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What hinder critical thinking

• Intellectual arroganceo Arrogance due to one’s education level or

qualifications refusing to think critically in open situations

• Intellectual lazinesso Just lazy to think critically

• Black & white thinkingo Those who think in one of the extremes without

considering all the intermediate possibilities


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Attribute of critical thinkers

• Rational• Think extra yard than others• Demand reasoning• Open minded• Ask right questions


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Attribute of critical thinkers (con.)

• Do not take anything for granted• Do not jump into conclusions• Do not fear challenging

politically/culturally dominant fallacies



How to practice critical thinking?

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Critical thinking steps

Analyze

Reasoning

EvaluateValidate

Conclude


Use formal logic Use scientific knowledge Look for real world examples

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How to do critical thinking?

1. Do careful, intentional thinking2. Analyze & evaluate each piece of the

argumento Identify facts and opinionso Evaluate the opinions

3. Use of reason or logic to check the validity4. Check truthfulness of each fact to see if it

is a sound argument5. Application/test with real world scenarios

to verify



Fact vs. opinion

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Fact vs. OpinionFact • A statement of fact can be proved TRUE

or FALSE using standard knowledgeo An observable or obvious thingo It has been proved by scientific experimentationo Can be deduced by formal logic

• Exampleo Earth is roundo Smoking causes cancero There is a force towards the earth


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Fact vs. OpinionOpinion• A statement of opinion is what someone

believes or thinkso He must provide enough evidence to prove his opinion

• Called burden of proofo We have to test if that opinion is valid or noto If we do not accept the opinion we must show the fault in the

opinion• We do not have to prove that opinion is false

o We may or may not provide alternative opinion• Example

o There is life after deatho Mr. X is a better leader than Mr. Y



Reasoning techniques

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Reasoning techniques• Deductive Reasoning

o Determines whether the truth of a conclusion can be determined for that rule, based solely on the truth of the premises

o The Best approach • Inductive Reasoning

o Attempts to support a determination of the ruleo Use with care

• Abductive Reasoningo a.k.a. inference to the best explanation, selects a cogent set

of preconditionso Use with care



Deductive reasoning

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Deductive Reasoning • Derive logically necessary conclusion

from given premises/ assumptionso Determines whether the truth of a conclusion can be

determined for that rule, based solely on the truth of the premises

• Mathematical logic and philosophical logic are commonly associated with this type of reasoning.


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How to come to judgements?

• Using formal logico Example 1:

X > 4y > xTherefore y >4

o Example 2: "When it rains, things outside get wet.” “The grass is outside.” Therefore, when it rains, the grass gets wet.

• Using scientific knowledgeo Example:

Removing oxygen will extinguish fireCovering with blanket remove/block oxygenTherefore, Covering with blanket will extinguish the fire


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What is an argument?

• An argument is set of assumptions/ premises followed by a conclusion

• Example:Socrates is a philosopher. (Assumption)All philosophers like thinking. (Assumption)Therefore Socrates likes thinking. (Conclusion)


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Outcome of an argument

Argument

Valid

Sound Unsound

Invalid


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What is a valid argument?• An argument is said to be valid if the

conclusion is logically true, whenever all the assumptions/premises are true

• Exampleo Valid argument

If there is an earthquake, the detector will send a message.No message has been sent.So there was no earthquake.

o Invalid argumentWhenever Anil is here, Kumar is also here.Anil is not here.So Kumar is not here.


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What is sound argument?

• If an argument is valid and all the assumptions are found/proved to be correct, then the argument is said to be sound.

• We must accept only the sound arguments!


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Valid & sound deductive argument - example

If husband is the president, then she is the first lady.

Barack is President of the USA.Michelle is the wife of Barack. => Therefore, Michelle is First

Lady.This argument is valid & sound.


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Valid but not sound deductive argument -

exampleIf the moon is made of green cheese,

then astronauts can eat moon rocks.

The moon is made of green cheese.=> Therefore, astronauts can eat

moon rocks.This argument is valid but unsound.


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Invalid deductive argument - example

If Abraham Lincoln died of cancer, then Lincoln is dead today.

Lincoln is dead today.=> Therefore, Abraham Lincoln

died of cancer.(This argument is invalid.)



Inductive reasoning

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Inductive Reasoning • Use patterns of concrete instances to

arrive at a conclusion• Attempts to support a determination of

the rule• It hypothesizes a rule after numerous

examples are taken to be a conclusion that follows from a precondition in terms of such a ruleo It’s a way of generalization through observation and

careful systematic analysis


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How to come to judgements?

• By analyzing results of empirical data using concepts of statistics and probabilityo Above 50% chance: Strong Argumento 50% or Less chance: Weak Argument

• Is the value considerably higher than average for a sample with particular feature

• Example: "The grass got wet numerous times when it rained, therefore: the grass always gets wet when it rains."


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Inductive Reasoning - caution

• Use of smaller sample may lead to false conclusion

• What is your visibility may be too narrow


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Inductive Reasoning - caution


What you have seen is not close to realityin general.

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Outcome of inductive reasoning

Reasoning

Strong

Cogent Not cogent

Weak


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Outcome of inductive reasoning

• Strong inductive argumento The truth of the premises really does prove that the

conclusion is probably true• Cogent inductive argument

o A strong inductive argument in which all the premises are actually true

• Not cogent inductive argument o A strong inductive argument in which at least one

premise is false.• Weak inductive argument

o The truth of the premises really does not prove that the conclusion is probably true


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Strong & cogent inductive argument -

exampleMost recording artists have talent.Britney Spears is a recording

artist.=> Therefore, Britney probably

has talent.This argument is strong and

cogent.Aurora Computer Studies (auroracs.lk)

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Strong but not cogent inductive argument -

exampleMost boys like to play sports.Britney Spears is a boy.=> Therefore, Britney probably

likes to play sports.This argument is strong but not

cogent.


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Weak inductive argument

Britney Spears is a recording artist.

Britney has blonde hair.=> Therefore, most recording

artists have blonde hair.This argument is weak.



Abductive reasoning

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Abductive Reasoning

• Abductive reasoning allows inferring a as an explanation of b

• As a result, abduction allows the precondition a to be adduced from the consequence b (i.e. effect to cause)

• Deductive reasoning and abductive reasoning thus differ in the direction in which a rule like " a entails b is used for inference.Aurora Computer Studies (auroracs.lk)

Incomplete observation

Best prediction(May be true)

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Abadductive Reasoning - caution

• Considerable risk of inferring wrong cause

• You may infer A as the cause, whereas actual cause might be C in this case


ABCD..

P

Q

R..

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Overview of reasoning


Generalrule

Specific conclusion(Always true)

Specific observation

General conclusion(May be true)

Incomplete observation

Best prediction(May be true)

Deductive Reasoning

Inductive Reasoning

Abductive Reasoning


Other helpful techniques for critical

thinking

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Tools/techniques for critical thinking

• Analysis, synthesis & application• What, Why & How? Approach• Abstraction• Root cause analysis


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Analysis, synthesis & application


Analysis Synthesis Application

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What, Why & How? approach


What? Why? How?

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Abstraction


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Abstraction - usages• Understanding mathematics• Design (model) before develop/

implement


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Root cause analysis• We must try to understand the

root causes rather than jump into consider immediate causes in order to solve problems

• Ask why five times


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Root cause analysis - example

The vehicle will not start. (the problem)Why? - The battery is dead. (First why)Why? - The alternator is not functioning. (Second why)Why? - The alternator belt has broken. (Third why)Why? - The alternator belt was well beyond its useful service life and not replaced. (Fourth why)Why? - The vehicle was not maintained according to the recommended service schedule. (Fifth why, a root cause)


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References• http://philosophy.hku.hk• https://

en.wikipedia.org/wiki/Critical_thinking

• https://en.wikipedia.org/wiki/Logical_reasoning

• https://en.wikipedia.org/wiki/Problem_of_induction

• https://en.wikipedia.org/wiki/5_WhysAurora Computer Studies (auroracs.lk)

http://philosophy.hku.hk/

http://philosophy.hku.hk/

https://en.wikipedia.org/wiki/Critical_thinking



https://en.wikipedia.org/wiki/Logical_reasoning



https://en.wikipedia.org/wiki/Problem_of_induction



https://en.wikipedia.org/wiki/5_Whys

https://en.wikipedia.org/wiki/5_Whys

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You may also like following

• If vs If and only if • Science, philosophy, religions an

d myths


https://www.slideshare.net/auroracslk/if-vs-if-and-only-if

https://www.slideshare.net/auroracslk/science-philosophyvsreligions

https://www.slideshare.net/auroracslk/science-philosophyvsreligions

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Thank You !Presented by Nalaka GamageAurora Computer Studies(auoracs.lk)

http://www.auoracs.lk/


"We are what we repeatedly do. Excellence, then, is not an act, but a habit." ~ Aristotle

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