Transcript GXEX1406 9 CAUSAL REASONING

GXEX1406
Thinking and Communication Skills
Causal Reasoning
What is
Causal Reasoning?
If you walk on a banana
skin you will slip !!!
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What is Causal Reasoning?
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Causal reasoning is a statement about cause and
effect.
It is human nature to seek a cause and effect for any
circumstances/events/occurrences.
CR attempts to show a definite relationship between
things; i.e. one event necessarily causes another. It
is a form of inductive reasoning in which an event(s)
is the result of another event(s).
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Definition
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One can observe that B follows A, but not
that B is caused by A.
A cause must precede its effect.
Example: Studying hard (antecedent) leads
to good grades (consequent)
Causal relationships are inferred, not directly
observed.
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Examples of Causal
Reasoning
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Drinking and driving causes traffic accidents.
A woman with blue eyes will have daughters
with blue eyes.
Violence on TV and in movies causes people
to like violence
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How Does CR Work ?
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We found that that such an object is followed by
such an effect
We foresee other similar objects, will be be followed
by similar effects
Example:
 The times I touched a hot iron with my bare
hands, I was badly burned.
__________________________________
 In the future, touching a hot iron will most likely
burn my finger.
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Reasoning Pattern
(Mill’s Method Of Reasoning)
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There is a set of five careful methods to
analyze and interpret our observations for the
purpose of drawing conclusions about the
causal relationships.
These are Mill’s Method Of Reasoning
In this course we will only consider two of the
methods.
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Mill’s Method Of Reasoning
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Method of Agreement
Method of Difference
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Scenario 1
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In order to illustrate these two methods we consider
the following scenario.
Suppose that on an otherwise uneventful afternoon,
the Doctor at the Klinik Kesihatan Mahasiswa
becomes aware that an unusual number of students
from FSKTM are suffering from severe indigestion.
Dr. Adam naturally suspects that this symptom
results from something the students ate for lunch,
and he would like to find out for sure.
(cont)
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Scenario 1
The Doctor wants to find evidence that
will support a conclusion that "Eating
?xxxx? causes indigestion."
 Mill's Methods can help.
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(cont)
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Mill’s Method of Agreement
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E.g..
Suppose that four students from
FSKTM come to see Dr. Adam with
indigestion, and he questions each about
what they had for lunch.
Dr. Adam: Can you tell me what you had for
lunch ?
(cont)
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Mill’s Method of Agreement
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First Student (Aziz): I had pizza, roti canai,
sugar cane, and an ice cream;
Second Student (Aisha): I had a burger
and chips, roti canai, and iced lemon tea;
Third Student (Mary): I ate pizza and roti
canai and drank iced lemon tea
Fourth Student(Lim): I ate only chips, roti
canai, and papaya.
(cont)
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Mill’s Method of Agreement
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Dr. Adam, concludes:
"Eating roti canai caused the indigestion."
(cont)
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Mill’s Method of Agreement
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Question: Is eating roti canai the only relevant
common factor preceding the indigestion?
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Only if it is can the argument be considered reliable.
Question: Could the indigestion be the result of
independent causes? (I.e. Maybe there was a viral
infection)
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The argument is reliable only if this possibility has been
eliminated.
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Mill’s First Method
(Method of Agreement)
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Generally,
X is the common thread.
X caused Y because X is the only relevant
common factor in more than one occurrence
of Y.
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Mill’s Method of Agreement
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Question: Is X the only relevant common
factor preceding the occurrences of Y?
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Only if it is can the argument be considered
reliable.
Question: Did the occurrences of Y result
from independent causes?
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The argument is reliable only if this possibility has
been eliminated.
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Mill's Method of Difference
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On the other hand, suppose that only two
students arrive at the Klinik.
The two are roommates who ate together, but
one became ill while the other did not.
The first had eaten a burger, chips, roti canai,
papaya and drank iced lemon tea,
The other had eaten a burger, chips, papaya,
and drank iced lemon tea.
Again, Dr. Adam concludes that the roti canai is
what made the first roommate ill.
(cont)
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Mill's Method of Difference
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This reasoning applies : comparison of a case in which the effect
occurred and another case in which the effect did not occur
revealed that only one prior circumstance was present in the first
case but not in the second.
In such situations, we commonly suppose that, other things being
equal, different effects are likely to arise from different causes,
and since only the student who had eaten roti canai became ill, it
was probably the cause.
(cont)
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Mill's Method of Difference
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Roti Canai is the difference.
Roti Canai caused indigestion because roti
canai is the only relevant difference between
this situation, where indigestion occurred,
and situations where indigestion did not
occur.
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Mill's Method of Difference
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Question: Is eating roti canai the only relevant
common factor preceding the indigestion?
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Only if it is can the argument be considered reliable.
Could the indigestion be the result of
independent causes? (Again, the viral infection)
The argument is reliable only if this possibility
has been eliminated.
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Mill’s 2nd Method
(Method of Difference)
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Generally,
X is the difference.
X caused Y because X is the only relevant
difference between this situation, where Y
occurred, and situations where Y did not
occur.
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Mill’s 2nd Method
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Question: Is X the only relevant common
factor preceding the occurrences of Y? (Only
if it is can the argument be considered
reliable.) Did the occurrences of Y result from
independent causes? (The argument is
reliable only if this possibility has been
eliminated.)
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Fallacies of Causality
1.
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3.
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5.
Questionable Cause aka Ignoring a
Common Cause
Assuming a Common Cause
Misidentification of the Cause
Slippery Slope
post hoc ergo propter hoc
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Fallacies of Causality:
Questionable Cause
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1.
This fallacy occurs when someone presents a
causal relationship for which no real evidence
exists.
AKA Ignoring a Common Cause
This fallacy has the following general structure:
X and Y are associated on a regular basis.
(but no third, common cause is looked for).
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Therefore X is the cause of Y.
(cont)
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Fallacies of Causality:
Questionable Cause
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The general idea behind this fallacy is that it is an error in
reasoning to conclude that one thing causes another simply
because the two are associated on a regular basis.
More formally, this fallacy is committed when it is concluded that
X is the cause of Y simply because they are associated on a
regular basis.
The error being made is that a causal conclusion is being drawn
from inadequate evidence.
Further, the causal conclusion is drawn without considering the
possibility that a third factor might be the cause of both X and Y.
(cont)
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Examples of Questionable
Cause
Example 1
1.
Ali gets a chain email that threatens him with dire
consequences if he breaks the chain.
2.
He laughs at it and throws it in the rubbish bin.
3.
On his way to work he slips and breaks his leg.
4.
When he gets back from the hospital he sends out
200 copies of the chain letter, hoping to avoid
further accidents.
(cont)
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Examples of Questionable Cause
Example 2
1.
A thunderstorm wakes Tan up in the middle of the night.
2.
He goes downstairs to get some milk to help him get back to
sleep.
3.
On the way to the refrigerator, he notices that the barometer has
fallen a great deal.
4.
Tan concludes that the storm caused the barometer to fall.
5.
In the morning he tells his wife about his conclusion.
6.
She tells him that it was a drop in atmospheric pressure that
caused the barometer to drop and the storm.
(cont)
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Fallacies of Causality:
Assuming a Common Cause
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This is the reverse of Ignoring a Common Cause (Questionable
Cause)
It consists of automatically assuming that two conjoined events
must have had the same underlying cause.
• This fallacy occurs by claiming a link between X and Y when
none exists.
The moral is, "Don't unthinkingly assume that two conjoined
occurrences have a common cause.
But don't unthinkingly assume that they do not, either".
(cont)
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Examples of Assuming a Common
Cause
"Both physicians ended up with cancer.
There must be something about treating sickness
that makes you get cancer.“
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Fallacies of Causality:
Misidentification of the Cause
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In causal situations, we are not always
certain about what is causing what.
i.e. what is the cause and what is the
effect.
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E.g.. "Headaches and tension"
"Failure is school and personal problems“
(cont)
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Fallacies of Causality:
Slippery Slope:
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One undesirable action will lead to a worse action,
which will lead to a worse one still, all the way down
the 'slippery slope' to some terrible disaster at the
bottom.
Although this progression my indeed happen, there
is certainly no causal guarantee that it will.
(cont)
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Examples of Slippery Slope
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If we let this lady check 11 items through the
6 item express checkout, you'll next be letting
people walk out the store without paying,
then speeding, murder and mayhem will be
allowed, the country will go to …
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Fallacies of Causality:
post hoc ergo propter hoc
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Causality plays such a dominant role in our lives, and many a
time mistakes or faulty reasoning occur.
post hoc fallacy
The post hoc ergo propter hoc (after this therefore because of
this) fallacy is based upon the mistaken notion that simply
because one thing happens after another, the first event was a
cause of the second event.
Post hoc reasoning is the basis for many superstitions and
erroneous beliefs.
(cont)
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Examples of
propter hoc
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post
hoc
ergo
You have a cold, so you drink fluids and two
weeks later your cold goes away.
You have a headache so you stand on your
head and six hours later your headache goes
away.
You put acne medication on a pimple and
three weeks later the pimple goes away.
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Testing Causal Relationships
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Is the cause necessary to produce the effect?
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Is it necessary to smoke to be cool?
Is the cause sufficient to produce the effect?
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E.g.:
E.g.:
Is wearing trendy clothes sufficient to be cool?
E.g.:
Is looking tanned or muscular synonymous with
being physically fit?
Are there alternative causal explanations
Are there cumulative (additional, contributory)
causes?
Are there countervailing causes?
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