Day 19 Research
 Outline due
Drafting Wednesday and Thursday
Draft due Friday for editing
Draft for grading due Monday
 Timed Reading
Review Previewing
Purpose
 Fallacies of Relevance
“The foolish and the dead alone
never change their opinion.”
- James Russell Lowell
4.2 Fallacies of Insufficient Evidence
Arguments in which the
premises, though
logically relevant to the
conclusion, fail to provide
sufficient evidence to
support the conclusion.
4.2 Fallacies of Insufficient Evidence
Inappropriate
Appeal to Authority
Appeal to Ignorance
Questionable
Cause
Slippery Slope
False Alternatives
Weak Analogy
Loaded Question
Inconsistency
Hasty Generalizations
4.2.1 Inappropriate Appeal to
Authority
Inappropriate Appeal to Authority
Citing a witness or authority that is untrustworthy.
Example:
My dentist told me that aliens built the lost city of
Atlantis. So, it’s reasonable to believe that
aliens did build the lost city of Atlantis.
Authority Assessment
Tips
1.
2.
3.
4.
5.
6.
7.
8.
Is the source an authority on the subject at issue?
Is the source biased?
Is the accuracy of the source observations questionable?
Is the source known to be generally unreliable?
Has the source been cited correctly?
Does the source’s claim conflict with expert opinion?
Can the source’s claim be settled by an appeal to expert opinion?
Is the claim highly improbable on its face?
4.2.2 Appeal to Ignorance
Appeal to Ignorance
Claiming that something is true because no one has
proven it false or vice versa.
Example:
Yoda must exist. No one has proved
that he doesn’t exist.
Agree
I do!
Remember
“Not proven, therefore false”
If such reasoning were allowed, we could prove almost
any conclusion.
4.2.3 False Alternatives
False Alternatives
Posing a false either/or choice.
Example:
The choice in this MPM election is clear: Either we elect
Zubaidah as our next president, or we watch our MPM
unity slide into anarchy and frustration. Clearly, we don’t
want that to happen. Therefore, we should elect
Zubaidah as our next president.
Remember
Fallacy of false alternatives can involve more than
two (2) alternatives. It can also be expressed as a
conditional (if-then) statement.
4.2.4 Loaded Question
Loaded Question
Posing a question that contains an unfair or unwarranted
presupposition.
Example:
Lee: Are you still friends with that loser Richard?
Ali: Yes.
Lee: Well, at least you admit he’s a total loser.
Tip
To respond to a loaded question effectively, one must
distinguish the different questions being asked and respond
to each individually.
4.2.5 Questionable Cause
Questionable Cause
Claiming, without sufficient evidence, that one thing
is the cause of something else.
Example:
Sarah gets a chain letter that threatens her with dire
consequences if she breaks the chain. She laughs
at it and throws it in the garbage. On her way to
work she slips and breaks her arm. When she gets
back from the hospital she sends out 200 copies of
the chain
to avoid
accidents.
1. letter,
A and Bhoping
are associated
on afurther
regular basis.
Pattern
2. Therefore A is the cause of B.
4.2.6 Hasty Generalization
Hasty Generalization
Drawing a general conclusion from a sample that
is biased or too small.
Example:
Norwegians are lazy. I have two friends who
are from there, and both of them never
prepare for class, or do their homework.
Pattern
1. A biased sample is one that is not representative of the target population.
2. The target population is the group of people or things that the
generalization is about.
3. Hasty generalizations can often lead to false stereotypes.
4.2.7 Slippery Slope
Slippery Slope
Claiming, without sufficient evidence, that a seemingly
harmless action, if taken, will lead to a disastrous
outcome.
Examples:
 “The Malaysian militarily shouldn't get involved in other countries. Once
the government sends in a few troops, it will then send in thousands to
die."
 If 10th graders are allowed to go out for lunch, they will be late to class,
fail out of school and become wandering vagrants.
1.
2.
Pattern
3.
The arguer claims that if a certain seemingly harmless action, A,
is permitted, A will lead to B, B will lead to C, and so on to D.
The arguer holds that D is a terrible thing and therefore should
not be permitted.
In fact, there is no good reason to believe that A will actually
lead to D.
4.2.8 Weak Analogy
Weak Analogy
Comparing things that aren’t really comparable.
Example:
Nobody would buy a car without first taking it for a test
drive. Why then shouldn’t two mature college students
live together before they decide whether to get married?
Tip
1. List all important similarities between the two cases.
2. List all important dissimilarities between the two cases.
3. Decide whether the similarities or dissimilarities are
more important.
4.2.9 Inconsistency
Inconsistency
Asserting inconsistent or contradictory claims.
Example:
Note found in a Forest Service Suggestion box: Park
visitors need to know how important it is to keep this
wilderness area completely pristine and undisturbed. So
why not put up a few signs to remind people of this fact?
Remember
It is also a mistake to cling stubbornly to an old idea when new
information suggests that the idea is false.
Open-minded to new ideas = Learning
4.2 Mini Quiz – Question 1
What's to say against [cigars]? They
killed George Burns at 100. If he
hadn't smoked them, he'd have died
at 75. (Bert Sugar, quoted in New
York Times, September 20, 2002)
Which fallacy?
A)
B)
C)
D)
Questionable Cause
Hasty Generalization
Slippery Slope
Weak Analogy
4.2 Mini Quiz – Question 2
According to North Korea's official state-run news agency,
"a war between North Korea and the United States will end
with the delightful victory of North Korea, a newly emerging
military power, in 100 hours. . . . The U. S. [will] be
enveloped in flames. . . and the arrogant empire of the devil
will breathe its last". Given that this prediction comes from
the official North Korean news agency, it is probably true.
(Passage quoted in Nicholas D. Kristof, "Empire of the Devil," New
York Times, April 4, 2003)
Which fallacy?
A)
B)
C)
D)
Inappropriate Appeal to Authority
Appeal to Ignorance
False Alternatives
Loaded Question
4.2 Mini Quiz – Question 3
Jurors in tobacco lawsuits should award judgments so
large that they put tobacco companies out of business.
Respecting the right of tobacco companies to stay in
business is akin to saying there are "two sides" to
slavery...
(Anti-tobacco lawyer, quoted in George F. Will, "Court Ruling
Expresses Anti-Smoking Hypocrisy," Wilkes-Barre Times
Leader, May 25, 2003)
Which fallacy?
A)
B)
C)
D)
Loaded Question
Hasty Generalization
Slippery Slope
Weak Analogy
Group Activity
 Break into groups of 4 - 6, and construct five (5) fallacious
arguments.
 Each group can choose any of the 20 fallacies discussed, but
must construct at least two fallacious arguments of each
category: Fallacies of Relevance & Fallacies of Insufficient
Evidence).
 The constructed fallacious arguments must discuss the
topics specified in the template provided (Business,
Education, Information Technology, Environment, and
Tourism).
20 min
Construct 5 fallacious arguments.
5 min
Document constructed arguments into the template provided.
15 min
Group presentation & discussion.
The Group leader must submit their findings in hard-copy or soft-copy format to
the lecturer before or during the next class.
Fallacy Fallacies
Summary – 20 Common
An argument that contains a mistake in reasoning.











Fallacies of Relevance
Arguments in which the premises are
logically irrelevant to the conclusion.
Fallacies of Insufficient Evidence
Arguments in which the premises, though
logically relevant to the conclusion, fail to
provide sufficient evidence for the
conclusion.
Personal Attack
Attacking the Motive
Look Who’s Talking
Two Wrongs Make a Right
Scare Tactics
Appeal to Pity
Bandwagon Argument
Straw Man
Red Herring
Equivocation
Begging the Question
 Inappropriate Appeal to
Authority
 Appeal to Ignorance
 False Alternatives
 Loaded Question
 Questionable Cause
 Hasty Generalization
 Slippery Slope
 Weak Analogy
References
Book
Chapter 5 (Logical Fallacies -1) & 6
(Logical Fallacies -2): G Bassham, W Irwin,
H Nardone, J M Wallace, Critical Thinking: A
Student's Introduction, McGraw-Hill
International Edition, 2007
Online Resources
Fallacies (The Nizkor Project):
http://www.nizkor.org/features/fallacies/
Contact Details
Zaid Ali Alsagoff
UNIVERSITI TUN ABDUL RAZAK
16-5, Jalan SS 6/12
47301 Kelana Jaya
Selangor Darul Ehsan
Malaysia
E-mail: zaid.alsagoff@gmail.com