2. Agenda
• What is critical thinking?
• How to practice critical thinking?
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3. What is critical thinking?
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4. What is critical thinking?
• Critical thinking is the ability to think
clearly and rationally about what to do
or what to believe.
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5. What is not critical thinking?
• Mere criticize everything
• Thinking a lot
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6. What hinder critical thinking
• Lack of awareness/practice of rational
(logical) thinking
o Those ignorant of how to think critically
• Personal biasness
o Some people deliberately avoid critical thinking on
situations where out come may put him in unfavorable
situation
• Inherited opinion/Cultural biasness
o Most of the people die with the opinions they inherit from
parents and close ones
o Example : More than 80% of those who born Islam will die
as Islam
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7. What hinder critical thinking
• Intellectual arrogance
o Arrogance due to one’s education level or
qualifications refusing to think critically in open
situations
• Intellectual laziness
o Just lazy to think critically
• Black & white thinking
o Those who think in one of the extremes without
considering all the intermediate possibilities
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8. Attribute of critical thinkers
• Rational
• Think extra yard than others
• Demand reasoning
• Open minded
• Ask right questions
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9. Attribute of critical thinkers (con.)
• Do not take anything for granted
• Do not jump into conclusions
• Do not fear challenging
politically/culturally dominant fallacies
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10. How to practice critical
thinking?
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12. How to do critical thinking?
1. Do careful, intentional thinking
2. Analyze & evaluate each piece of the
argument
o Identify facts and opinions
o Evaluate the opinions
3. Use of reason or logic to check the
validity
4. Check truthfulness of each fact to see if it
is a sound argument
5. Application/test with real world scenarios
to verify
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14. Fact vs. Opinion
Fact
• A statement of fact can be proved TRUE
or FALSE using standard knowledge
o An observable or obvious thing
o It has been proved by scientific experimentation
o Can be deduced by formal logic
• Example
o Earth is round
o Smoking causes cancer
o There is a force towards the earth
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15. Fact vs. Opinion
Opinion
• A statement of opinion is what someone
believes or thinks
o He must provide enough evidence to prove his opinion
• Called burden of proof
o We have to test if that opinion is valid or not
o 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 death
o Mr. X is a better leader than Mr. Y
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17. 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 rule
o Use with care
• Abductive Reasoning
o a.k.a. inference to the best explanation, selects a cogent
set of preconditions
o Use with care
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19. Deductive Reasoning
• Derive logically necessary conclusion
from given premises/ assumptions
o 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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20. How to come to judgements?
• Using formal logic
o Example 1:
X > 4
y > x
Therefore 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 knowledge
o Example:
Removing oxygen will extinguish fire
Covering with blanket remove/block oxygen
Therefore, Covering with blanket will extinguish the fire
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21. 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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22. Outcome of an argument
Argument
Valid
Sound Unsound
Invalid
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23. 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
• Example
o 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 argument
Whenever Anil is here, Kumar is also here.
Anil is not here.
So Kumar is not here.
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24. 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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25. 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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26. Valid but not sound deductive
argument - example
If 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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27. 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.)
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29. 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 rule
o It’s a way of generalization through observation and
careful systematic analysis
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30. How to come to judgements?
• By analyzing results of empirical data using
concepts of statistics and probability
o Above 50% chance: Strong Argument
o 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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31. Inductive Reasoning - caution
• Use of smaller sample may lead to
false conclusion
• What is your visibility may be too
narrow
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32. Inductive Reasoning - caution
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What you have seen
is not close to reality
in general.
33. Outcome of inductive reasoning
Reasoning
Strong
Cogent
Not
cogent
Weak
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34. Outcome of inductive reasoning
• Strong inductive argument
o 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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35. Strong & cogent
inductive argument - example
Most recording artists have talent.
Britney Spears is a recording artist.
=> Therefore, Britney probably has
talent.
This argument is strong and cogent.
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36. Strong but not cogent inductive
argument - example
Most 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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37. Weak inductive argument
Britney Spears is a recording artist.
Britney has blonde hair.
=> Therefore, most recording artists
have blonde hair.
This argument is weak.
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39. 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.
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Incomplete
observation
Best prediction
(May be true)
40. 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
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A
B
C
D
.
.
P
Q
R
.
.
41. Overview of reasoning
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General
rule
Specific conclusion
(Always true)
Specific
observation
General conclusion
(May be true)
Incomplete
observation
Best prediction
(May be true)
Deductive Reasoning
Inductive Reasoning
Abductive Reasoning
48. 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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50. 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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