It’s Autumn Now!
• Inquiring Minds
• report out on homework
• fallacies pt1
Module 4:
Fallacies
Zaid Ali Alsagoff
zaid.alsagoff@gmail.c
om
Man or Woman?
Source: http://www.coolopticalillusions.com/manwoman.htm
How many legs does this
elephant have?
Source: http://www.coolopticalillusions.com/elephantlegs.htm
Which officer is the tallest?
Source: http://www.coolopticalillusions.com/optical_illusions_images_2/giant_man.htm
Is this wave moving?
Source: http://www.grand-illusions.com/opticalillusions/oblong_wave/
Analyze
+
Evaluate
=
Your Opinion?
Target Audience?
AirAsia +
Girls = Fun
Module 4: Fallacies
1. Fallacies
of Relevance
What
mistake!!!
2. Fallacies of
Insufficient
Evidence
4.0 What is a Fallacy?
• A (logical) fallacy is an argument
that contains a mistake in
reasoning.
• Fallacies can be divided into two
general types:
– Fallacies of Relevance
Arguments in which the premises are
logically irrelevant to the conclusion.
“There is nothing so stupid as an educated man,
if you get him off the thing he was educated in”
- Will Rogers
4.1 Fallacies of Relevance
• A statement is RELEVANT to another
statement if it provides at least some
reason for thinking that the second
statement is true or false.
• There are three ways in which a
statement can be relevant or irrelevant
to another:
– A statement is positively relevant to another
statement if it provides at least some reason for
4.1 Fallacies of Relevance
Personal
Attack
Attacking the
Motive
Look Who’s
Talking
Begging the
Question
Appeal to Pity
Bandwagon
Argument
Straw Man
Red Herring
4.1.1 Personal Attack
Personal Attack/Ad Hominem
When an arguer rejects a person’s argument or claim
by attacking the person’s character rather than
examining the worth of the argument or claim itself.
Example:
Professor Doogie has argued for more
emphasis on music to facilitate
creativity. But Doogie is a selfish
bigheaded fool. I absolutely refuse to
1. X is a bad person.
listen to
him.
Pattern
2. Therefore X's argument must be bad.
4.1.2 Attacking the Motive
Attacking the Motive
When an arguer criticizes a person’s motivation for
offering a particular argument or claim, rather than
examining the worth of the argument or claim itself.
Example:
The Senator claims that congressional
salaries should be raised. He says
business executives doing comparable
work make much more and that
congressional
haven't
kept pace
1. X has biased salaries
or has questionable
motives.
Pattern 2. Therefore, X’s arguments or claim should be rejected.
with inflation. But keep in mind what he
4.1.3 Look Who’s Talking
Look Who’s Talking (tu quoque)
When an arguer rejects another person’s argument
or claim because that person is a hypocrite.
Example:
Doctor: You should quit smoking.
Patient: Look who’s talking! I’ll quit when you
do, Dr. Smokestack!
How can you tell me I should exercise to lose
weight? All you do is sit behind a desk all day.
I've never
seen
you
a own
lickadvice.
of exercise
1. X fails
to follow
his do
or her
Pattern
2. Therefore, X’s claim or argument should be rejected.
4.1.4 Two Wrongs Make a
Right
Two Wrongs Make a Right
When an arguer attempts to justify a wrongful act
by claiming that some other act is just as bad or worse.
Examples:
“I don’t feel guilty about cheating
on the quiz. Half the class
cheats.”
“Why pick on me, officer? Everyone
1.is
Others
are committing
worse or equally bad acts.
else
using
drugs.”
Pattern
2. Therefore my wrongful act is justified.
4.1.5 Scare Tactics
Scare Tactics
When an arguer threatens harm to a reader or listener
and this threat is irrelevant to the truth of
the arguer’s conclusion.
Example:
Diplomat to diplomat: I’m sure you’ll
agree that we are the rightful rulers of
the Iraq. It would be regrettable if we
had to
send
armed
forces
to
Fear
is a powerful
motivator
– so powerful
that it often
Remember
causes us to think
behave irrationally.
demonstrate
theand
validity
of our claim.
4.1.6 Appeal to Pity
Appeal to Pity
When an arguer attempts to evoke feelings of pity or
compassion, where such feelings, however understandable,
are not relevant to the truth of the arguer’s conclusion.
Example:
Student to Lecturer: I know I missed half your
classes and failed all my quizzes and assignments.
First my cat died. Then my girlfriend told me she
has found someone else. With all I went through
this semester, I don’t think I really deserve an F.
Any chance
might cutwith
me the
some
slack
1. Pyou
is presented,
intent
to and
create pity.
Pattern
change my
grade to a
C orC aisD?
2. Therefore
claim
true.
4.1.7 Bandwagon Argument
Bandwagon Argument (Peer Pressure)
When an arguer appeals to a person’s desire to be popular,
accepted, or valued, rather than to logically relevant
reasons or evidence.
Example:
All the really cool students smoke
cigarettes. Therefore, you should, too.
Pattern
1. Most (or a select group of) people believe or do X.
2. Therefore, you should believe or do X.
4.1.8 Straw Man
Straw Man
When an arguer misrepresents another person’s
position to make it easier to attack.
Example:
Singh and Karen are arguing about cleaning
out their closets:
Suzie: "We should clean out the closets.
They are getting a bit messy.“
Singh:
"Why, we just went through those
1. Person A has position X.
closets
last Byear.
weY have
cleanversion of X).
2. Person
presentsDo
position
(which is to
a distorted
Person B attacks position Y.
Pattern
them 3.
out
everyday?"
4. Therefore X is false/incorrect/flawed.
4.1.9 Red Herring
Red Herring
When an arguer tries to sidetrack his audience by raising
an irrelevant issue, and then claims that the original
issue has been effectively settled by the
irrelevant diversion.
Example:
"I think there is great merit in making the
requirements stricter for the graduation. I
recommend that you support it, too. After
Topic A is under discussion.
all, 1.2.we
are
in a budget
we do
Topic
B is introduced
under thecrisis
guise of and
being relevant
to topicour
A (when
topic B is actually
not relevant to topic A).
not want
salaries
affected."
Pattern
3. Topic A is abandoned.
4.1.10 Equivocation
Equivocation
When an arguer uses a key word in an argument in two
(or more) different senses.
Example:
In the summer of 1940, Londoners were
bombed almost every night. To be bombed
is to be intoxicated. Therefore, in the
summer of 1940, Londoners were
intoxicated almost every night.
Hot dogs
are better
than can
nothing
Fallacies
of Equivocation
be difficult to spot because
Remember
often appear
valid,
but they aren’t.
Nothingthey
is better
than
steak.
4.1.11 Begging the
Question
Begging the Question
When an arguer states or assumes as a premise (reason)
the very thing he is seeking to probe as a conclusion.
Example:
I am entitled to say whatever I choose
because I have a right to say whatever
I please.
Reason
Arguing in a circle – A because B, B because A.
4.1 Mini Quiz – Question 1
I'm trying hard to understand this guy
who identifies himself as a security
supervisor and criticizes the police
officers in this area. I can only come up
with two solutions. One, he is either a
member of the criminal element, or
Which
fallacy?
two,
he is a frustrated security guard
who can never make it as a police
A) Loaded
Question
officer
and figures he can take cheap
B) Personal Attack
shots at cops through the newspaper
C) Bandwagon Argument
(adapted from a newspaper call-in
D) Scare Tactics
column).
4.1 Mini Quiz – Question 2
The Red Cross is worried
about the treatment of the
suspected terrorists held by
the U.S. at Guantanamo Bay,
Cuba. What do they want the
U.S. to do with them, put them
Which
fallacy?
on
the beaches of Florida for a
vacation
or
take
them
skiing
in
A) Bandwagon Argument
the Rockies? Come on, let's
B) Personal Attack
worry
C) Straw
Man about the Americans.
(adapted
from a newspaper
D) Scare
Tactics
call-in column)
“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
4.2 Fallacies of Insufficient
Evidence
Inappropriate
Appeal to
Authority
Appeal to
Ignorance
False
Alternatives
Loaded
Question
Questionable
Cause
Slippery Slope
Weak Analogy
Inconsistency
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
Authority Assessment
reasonable
to anbelieve
that
did
1.
Is the source
authority on the
subjectaliens
at issue?
Is the source biased?
build 2.3.the
lost
city
Atlantis.
Is the
accuracy
of theof
source
observations questionable?
Tips
4.
5.
6.
7.
8.
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:
I’ve never seen a rainbow, so there’s
no such thing.
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 election is clear:
Either we elect my candidate as our
next president, or we watch our
country slide into anarchy and
frustration.
Clearly,
we
don’t
want
Fallacy of false alternatives can involve more than
that
to
Therefore,
we
should
two happen.
(2) alternatives.
It can also be expressed
as a
Remember
conditional (if-then) statement.
elect my candidate as our next
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
To respond to a loaded question effectively, one must
loser. the different questions being asked and respond
Tiptotal distinguish
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
out
copies
1. A andshe
B aresends
associated
on 200
a regular
basis. of the
Pattern
chain letter,
hoping
tocause
avoid
2. Therefore
A is the
of B.further
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.
1. A biased sampleare
is one that
is not representative
of the target population.
All teenagers
rude
and
Pattern 2. The target population is the group of people or things that the
generalization is about.
disrespectful.
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 militarily shouldn't get involved in
other countries. Once the government
sends in a few troops, it will then send in
thousands
to die."
1.
The arguer claims that if a certain seemingly harmless action, A,
is permitted,are
A will lead
to B, B will lead
C, and
so onfor
to D.
• If 10th graders
allowed
to togo
out
The arguer holds that D is a terrible thing and therefore should
lunch,2. they
be late to class, fail out of
not be will
permitted.
In fact,
there is no good
reason to believe that
A will actually
school3. and
become
wandering
vagrants.
Pattern
lead to D.