ENG 102 Section 5

1. Logical fallacies
Week 9

2. Major premise
Minor premise
Conclusion

4. Remember these?
• Deductive Reasoning (Syllogisms)
• Argument: premise + premise => conclusion
• Faulty Syllogisms
• Unsound (or untrue) premise
• Invalid conclusion
• These faulty syllogisms are basic LOGICAL FALLACIES.
• Inductive reasoning
• Reasoning based on available evidence / clues
• If reasoning goes wrong: LOGICAL FALLACY

5. Logical fallacies
• A fallacy is an error of reasoning. These are flawed statements that often sound
true.
• Logical fallacies are often used to strengthen an argument, but if the reader
detects them the argument can backfire, and damage the writer’s credibility
• It is important to develop logical fallacy detection skills in your own
writing, as well as in that of others.
Able to spot poor reasoning & know why it is wrong
Able to correct other’s mistakes, or refute them convincingly
Supplements your knowledge on logic
Know when your reasoning in an essay is flawed or questionable
Prevent you from making generalized statements without backing it up with
sound evidence

6. Important to realize
• Fallaciousness is a matter of degree.
• An argument may be “somewhat” fallacious, “probably”
fallacious, “slightly” fallacious, “highly” fallacious, and so on.
• Just because an argument is fallacious to some degree
doesn’t exclude the argument from consideration.

7. 1. Red herring
•is a kind of fallacy that is an irrelevant topic
introduced in an argument to divert the attention
of listeners or readers from the original issue.
Why should we donate to Greenpeace when we still
have people living in poverty?

8. 2. Post Hoc Fallacy
• A happened
before B.
• (unstated) B was
caused by
something (that
happened
before B).
• Therefore, A cause
d B.

9. 3. Circular reasoning
• Circular reasoning (also known as
circular logic) is a logical fallacy in which
the reasoner begins with what they are
trying to end with.
• The components of a circular
argument are often logically valid
because if the premises are true, the
conclusion must be true.
• Occurs when you try to prove the
statement by simply repeating it in
different words.
• A is true because B is true.
• B is true because A is true.

10. 4. Hasty generalization
• This fallacy occurs when an arguer draws a general
conclusion from a sample that is either biased or too small.
• Hasty generalizations can often lead to false
stereotypes.
• X is true for A.
• X is true for B.
• Therefore, X is true for C, D, etc.
I’ve had three students from Country X in the past year.
All three were lazy. Obviously all students from Country
X are lazy.

11. 5. Appeal to tradition
• is a common fallacy in which a thesis is deemed correct on the basis
that it is correlated with some past or present tradition. The appeal
takes the form of "this is right because we've always done it this
way."
X is old or traditional. Therefore X is correct or better.
Scolding a student who misbehaves is still the best way to
instill discipline because it has been done by teachers and
parents in the past.
• An appeal to tradition essentially makes two assumptions that are
not necessarily true:
• The old way of thinking was proven correct when introduced
• The past justifications for the tradition are still valid at present.

12. 6. False dilemma
• is a type of informal fallacy that involves a situation in which only
limited alternatives are considered, when in fact there is at least
one additional option.
If we don't reduce public spending, our economy will collapse.
America: Love it or leave it.
Politician: We have to decide if we are going to support school choice
or if we are going to support failing schools. Those are the only two
options.

13. 7. Appeal to fear
• An appeal to fear is a fallacy in which a person attempts to
create support for an idea by using deception and
propaganda in attempts to increase fear and prejudice
toward a competitor.
• Either or P or Q is true
• P = frightening
• Therefore, Q is true
My mom is this school's biggest donor, so you should really reconsider
that C you gave me on my latest paper.
A commercial for a political candidate that argues that his opponent's
support of amnesty for illegal immigrants will open our country to
terrorism.

14. 8. False analogy
• The assumption that because two things are alike in some
respects, they are alike in others.
• A and B are shown to be similar. Therefore, they both are
X.
• Students are like nails. Just as nails must be hit in the head in
order to make them work, so must students.

15. 9. Non Sequitur (“It Does Not
Follow”)
 Claim A is made.
 Evidence is presented for claim A.
 Therefore, claim C is true.
Buddy Burger has the greatest food in
town. Buddy Burger was voted #1 by the local
paper. Therefore, Phil, the owner of Buddy
Burger, should run for president of the United
States.

16. Identify and
explain the
fallacies in the
following
arguments.
1. Why worry about the Pandas becoming extinct when we have a
large number of homeless in our own country?
2. Cellphone users have increased exponentially in the last 20 years.
Researchers discovered that the incidences of brain cancer have
also increased in that time. Therefore, cellphone usage must cause
brain cancer.
3. Mrs. Smith’s drama club attracts a large number of students
because many students come to the drama club.
4. My roommate said her philosophy class was hard, and the one I’m
in is hard, too. All Philosophy classes must be hard.
5. Books are still the best sources of information because they have
been used for thousands of years.
6. Either medicine can explain how Ms. X was cured, or it is a
miracle. Medicine can't explain how she was cured. Therefore it is
a miracle.
7. If you don’t study hard, you will fail. If you fail, your future is
doomed. Therefore, you need to study hard.
8. People who cannot go without their coffee every morning are no
better than alcoholics.
9. People generally like to walk on the beach. Beaches have
sand. Therefore, having sand floors in homes would be a great
a. Post Hoc fallacy
b. False Dilemma
c. Hasty
generalization
d. Red Herring
e. False Analogy
f. Appeal to Tradition
g. Appeal to Fear
h. Circular Reasoning
i. Non Sequitur (“It
Does Not Follow”)
D
A
H
C
F
B
G
E
I

17. GXEX1406 Thinking and Communication Skills – Week 12
Logical Fallacies
17
Identify & explain the logical
fallacy in the following
statements.
WARMING UP

18. 18
1. The women in my family love babies.
All women love babies
1. Hasty generalization
2. Circular reasoning
3. Red herring
4. Post hoc fallacy
5. Appeal to tradition
6. False dilemma
7. Appeal to fear /scare Ad hominem
8. False analogy

19. GXEX1406 Thinking and Communication Skills – Week 12
Logical Fallacies
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Faulty logic – unqualified
A generalization. This fallacy is
committed when a person draws
a conclusion about a population
based on a sample that is not
large enough
1. All women in my family love babies.
All women love babies.
Hasty generalization

20. GXEX1406 Thinking and Communication Skills – Week 12
Logical Fallacies
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2. You shouldn’t accept national
health care because it is a socialist idea.
1. Hasty generalization
2. Circular reasoning
3. Red herring
4. Post hoc fallacy
5. Appeal to tradition
6. False dilemma
7. Appeal to fear /scare Ad hominem
8. False analogy

21. GXEX1406 Thinking and Communication Skills – Week 12
Logical Fallacies
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2. You shouldn’t accept national
health care because it is a socialist idea
Red herring
Switching to another issue to distract
from the main argument. This sort of
"reasoning" is fallacious because
merely changing the topic of
discussion hardly counts as an
argument against a claim.

22. GXEX1406 Thinking and Communication Skills – Week 12
Logical Fallacies
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3. In a democracy the people are free
because democracies are free countries.
1. Hasty generalization
2. Circular reasoning
3. Red herring
4. Post hoc fallacy
5. Appeal to tradition
6. False dilemma
7. Appeal to fear /scare Ad hominem
8. False analogy

23. GXEX1406 Thinking and Communication Skills – Week 12
Logical Fallacies
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3. In a democracy the people are free
because democracies are free countries.
Circular argument
This sort of "reasoning" is fallacious because
simply assuming that the premise is true does
not constitute evidence for that conclusion.
Democracy = free country = free people.
Circular argument with no end.

24. 24
4. The gang members caught by the police last
night comprises immigrants from country X.
Most immigrants who work in this country
have trouble with the law and come from
country X where thievery are rampant.
1. Hasty generalization
2. Circular reasoning
3. Red herring
4. Post hoc fallacy
5. Appeal to tradition
6. False dilemma
7. Appeal to fear /scare Ad hominem
8. False analogy

25. GXEX1406 Thinking and Communication Skills – Week 12
Logical Fallacies
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Hasty generalization
Faulty logic – unqualified
Generalization. Making a
judgment based on a small
Sample.
4. The gang members caught by the police last
night comprises immigrants from country X.
Most immigrants who work in this country
have trouble with the law and come from
country X where thievery are rampant.

26. 26
5. Bernie Sanders was the best candidate
for president, because he was totally
better than any of the others.
1. Hasty generalization
2. Circular reasoning
3. Red herring
4. Post hoc fallacy
5. Appeal to tradition
6. False dilemma
7. Appeal to fear /scare Ad hominem
8. False analogy

27. GXEX1406 Thinking and Communication Skills – Week 12
Logical Fallacies
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Assumption -- Sanders is better than the other
candidates, conclusion -- Sanders is the best.
This sort of "reasoning" is fallacious because
simply assuming that the conclusion is true
(directly or indirectly) in the premises does not
constitute evidence for that conclusion.
Begging the question/
Circular argument
5. Bernie Sanders was the best candidate
for president, because he was totally
better than any of the others.

28. 28
6. If you don't finish your homework you
won't get a good grade. Then you won't be
able to get into the college you want. You
will end up cleaning toilets for a living.
1. Hasty generalization
2. Circular reasoning
3. Red herring
4. Post hoc fallacy
5. Appeal to tradition
6. False dilemma
7. Appeal to fear /scare Ad hominem
8. False analogy

29. GXEX1406 Thinking and Communication Skills – Week 12
Logical Fallacies
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Appeal to fear /scare tactics
It is an appeal to force or threat
instead of trying to convince
someone with facts or a logical
argument
6. If you don't finish your homework you
won't get a good grade. Then you won't be
able to get into the college you want. You
will end up cleaning toilets for a living.

30. 30
7. Women need to be either brilliant or
beautiful to survive in this world.
1. Hasty generalization
2. Circular reasoning
3. Red herring
4. Post hoc fallacy
5. Appeal to tradition
6. False dilemma
7. Appeal to fear /scare Ad hominem
8. False analogy

31. GXEX1406 Thinking and Communication Skills – Week 12
Logical Fallacies
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False dilemma
Include either…or… . Just gives two
opposite extremes instead of allowing
for other possibilities. Not all women
who survive in this world are brilliant
or beautiful.
7. Women need to be either brilliant or
beautiful to survive in this world.

32. 32
8. The rooster crowed and the sun came
up. Therefore, the rooster causes the sun to
come up.
1. Hasty generalization
2. Circular reasoning
3. Red herring
4. Post hoc fallacy
5. Appeal to tradition
6. False dilemma
7. Appeal to fear /scare Ad hominem
8. False analogy

33. GXEX1406 Thinking and Communication Skills – Week 12
Logical Fallacies
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Post Hoc
The post hoc fallacy is committed
when it is assumed that because one
thing occurred after another, it must
have occurred as a result of it.
8. The rooster crowed and the sun came
up. Therefore, the rooster causes the sun to
come up.

34. 34
1. Hasty
generalization
2. Circular reasoning
3. Red herring
4. Post hoc fallacy
5. Appeal to tradition
6. False dilemma
7. Appeal to fear
/scare Ad hominem
8. False analogy

35. GXEX1406 Thinking and Communication Skills – Week 12
Logical Fallacies
35
Appeal to tradition
Appeal to Tradition is a fallacy that occurs
when it is assumed that something is better or
correct simply because it is older, traditional,
or "always has been done." This sort of
"reasoning" has the following form: X is old or
traditional. Therefore X is correct or better.
9. Marriage should be between a man and
a woman because it has been this way for
hundreds of years.

36. 36
1. Hasty
generalization
2. Circular reasoning
3. Red herring
4. Post hoc fallacy
5. Appeal to tradition
6. False dilemma
7. Appeal to fear
/scare Ad hominem
8. False analogy

37. 37
False analogy
when a comparison is
made between two
ideas or objects that
seemingly have similar
characteristics, but the
comparison does not
hold up. The
characteristics of the
two things actually
differ in the area that
is being compared.

38. JIGSAW ACTIVITY
Your team will receive a picture. Together decide what
fallacy/fallacies it illustrates. Why did you say this? Do
you think the fallacy used is effective or not?
1.Hasty generalization
2.Circular reasoning
3.Red herring
4.Post hoc fallacy
5.Appeal to tradition
6.False dilemma
7.Appeal to fear /scare
8.False analogy

45. Evaluate your arguments in pairs.
Check if you have committed
fallacies.
1. The Olympic Games promote nationalism and this is not a
good thing.
2. Songkran 2017 caused nearly 300 people died due to 3,000
accidents injuring almost 3,100 people (Bangkokpost, 17 April
2017). These numbers prove that Thailand is not safe
anymore.
3. PokemonGo brings people together in the quest for a
common goal and it does so by promoting exercise: it
therefore is the best game ever!