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Logical FallaciesLSH 2203 Critical Thinking
FallaciesA fallacy is an argument that contains a mistake in reasoning.
Comes from th
e same
word fa
mily as ‘fa
lse’!
“Oh, so you think it is better for all the
women in our office to wear mini-
skirts?”
“I don’t think women should wear a niqab at
work.”
What’s wrong with this argument?
Anna Bea
Anna never said anything about mini-skirts. She simply stated that she didn’t think women
should cover their face in the workplace.
Bea exaggerated Anna’s argument to mean that she supports mini-skirts. Bea put words in
Anna’s mouth.
This is an example of ONE of many kinds of fallacies we will see in this unit.
Why do you think Bea would make this kind of comment?
What might Bea say next?
Why do people use fallacies?
Sometimes people use fallacies without knowing it.
• They may be misinformed• They may be poor at using
critical thinking.
Why do people use fallacies?
Sometimes people use fallacies on purpose.
Can you think of reasons people might do this?
An important part of being a good critical thinker is being able to check arguments for
fallacies.
Types of FallaciesFallacies of Relevance
&Fallacies of Insufficient Information
Fallacies of Relevance
Remem
ber a
criti
cal
thin
ker h
as to
be
rele
vant!
In Fallacies of Relevance - the premises are not relevant to the
conclusion.
? ? so…
Fallacies of Relevance
1. Personal Attack (Ad Hominem)2. Scare Tactics3. Bandwagon Argument (Ad Populum)4. Red Herring5. Straw Man6. Begging the Question7. Appeal to Pity
Personal Attack (Ad Hominem) Latin - at a
person
Investing in technology will
help our economy.
Jack doesn’t even have a job at the
moment! We can’t trust anything he
says!
Jack
What’s wrong with the argument against Jack’s idea?
Jack says we should invest in
technology
Jack has no job.
so…Jack’s idea
must be bad.
A Personal Attack is when someone attacks the qualities and/or characteristics of a
person instead of the argument the person presents.
The information might be true (Jack might have no job), but the person’s character is irrelevant to the argument that is made.
Can you think of personal examples of this?
Scare Tactics
An example of using scare tactics:
The NRA, or National Rifle Association, want Americans to be
able to have guns to defend themselves.
Obama is a Democrat. Usually Democrats vote against Americans having more opportunities to get
guns.
http://www.youtube.com/watch?v=f5zNz0n7efk
This video is made by the NRA. Do you feel ‘scared’? What is their argument?
What’s wrong with this argument?
Obama supports
gun control.
If you agree with Obama,
someone might break into your house and you
won’t be able to stop them
because you won’t have a
gun!
so…You must
not vote for Obama.
Scare tactics happen when the speaker threatens or tries to frighten
the listener if the listener won’t accept the argument.
Can you think of personal examples of this?
Bandwagon Argument(Ad Populum)
The Ice-bucket Challenge
http://www.telegraph.co.uk/men/the-filter/virals/11045803/Ice-bucket-challenge-fails-20-of-the-best-videos-so-far.html
http://www.youtube.com/watch?v=-4smHMO1Crg
What do you know about Ice-bucket challenge?
Why do people do it?
Do you think too many people did it? Is it still popular?
http://www.telegraph.co.uk/men/the-filter/virals/11045803/Ice-bucket-challenge-fails-20-of-the-best-videos-so-far.html
http://www.youtube.com/watch?v=-4smHMO1Crg
What’s wrong with this argument?
I don’t know
what an ice-bucket challenge is about.
But everybody
else is doing an
ice-bucket challenge.
so…
I should do an ice-bucket
challenge.
https://www.dropbox.com/sh/k4c7ey3tni6g5tn/TCeZzHyvZGThis example is from a comedy show. This is a joke about how some politicians make their decisions. What is wrong with this argument?
A Bandwagon fallacy occurs when an argument appeals to people’s desire to
be popular or fit into the group. It argues that it must be true because all
people believe it or do it.
Can you think of personal examples of this?
Red Herring
A news story…
Trayvon Martin was killed in Florida in 2012 when he was
walking home.
He was 17 years old, unarmed and
wearing a hoodie. He was shot in the
chest by a neighbourhood watch volunteer,
George Zimmerman.
Zimmerman said that he had argued with Trayvon and that he
used the gun in self-defense.
Because of this, Zimmerman did not go to jail.
However, some Americans felt that Zimmerman had killed
Trayvon because he was black and believed that he was afraid
of, or intimidated by, black teenagers.
What do you think?
The argument against Zimmerman.
Zimmerman shot Trayvon
because he was black,
not to defend himself.
It is illegal to kill
someone unless you
are defending yourself.
so…
Zimmerman broke the law and should go
to jail
The media added some extra information to the arguments.
Trayvon had some drugs in his bag!
Trayvon was suspended from school at the time!
He had a backpack
with stolen earrings ad rings in it!
He spray-painted
graffiti on the walls at his school!
What’s wrong with this argument?
Trayvon was a bad
kid!
Zimmerman shot
Trayvon because he was black,
not to defend himself.
so
It is illegal to kill
someone unless you
are defending yourself.
so
These extra facts are not related to the events of the crime. They confuse us and take our mind
away from the real facts. These are red herrings.
Example 2 : http://www.cbsnews.com/news/obama-ad-attacks-mccain-for-owning-seven-houses/What argument does the Barack Obama campaign make? What was the original issue? How does that change?
A red herring fallacy occurs when the arguer raises an irrelevant issue
which takes the whole argument in a different direction. Sometimes it completely changes the subject.
Can you think of personal examples of this?
Straw Man
A strong argument
A new, weaker
argument.
http://www.youtube.com/watch?v=sT_VhDrn8NYHow did the argument get exaggerated?
She voted for this war which I would not have voted for.
So you’d rather see Sadam (Hussein) back in power?No, but I would like to see a plan to
victory in Iraq.Stay the course? (means keep doing
the same thing – e.g. war)
What’s wrong with this?
My argument.
so… A different
conclusion.You mean
“…..”You mean
“…..”
My argument.
so… My conclusion.
For example…
There are a lot of
accidents on this
highway.
so “you
mean”…
We should
turn this
road into a
bicycle
lane!
You mean “
hundreds
of people
are dying
every
year!”
You mean
“even when
people
drive 50
kms an
hour they
still have
accidents!”
Speed limits at around 50kms
hour lower accident
rates.
so…
This highway
should have a 50 km
speed limit.
Straw Man fallacy occurs when the arguer changes or exaggerates the
other person’s argument so it is easy to attack.
Can you think of personal examples of this?
Begging the Question
There are two ways that begging the question can happen in an argument.
What’s wrong with this argument?
so Sky diving
is dangerous.
Sky diving is not safe.
The premise and the conclusion are the same idea.
What’s wrong with this argument?
because becauseHCT is better
than ZU.
HCT has better
students than ZU.
HCT has better
teachers than ZU.
because
There are no premises or reasons – just more conclusions based on the last
conclusion.
Begging the question occurs when the arguer says nearly the same thing in the premise and in the conclusion.
It assumes the conclusion is true in the premise.
Can you think of personal examples of this?
Appeal to Pity
Teachers are often asked to change the rules by students.
What kind of changes do you think students ask for?
What arguments do you think are strong/weak?
What’s wrong with this argument?
I missed a lot of
classes and didn’t have time to study.
so I failed the
course.
Yes, but Miss/Sir, I had a lot of problems at
work and was sick.
Please don’t fail me! I
don’t deserve to fail!
I didn’t pass the
tests because I
didn’t know the
topic.
This fallacy occurs when the arguer tries to get the listener to feel pity or compassion to convince him or her to
change their conclusion.
What is the problem with this?
Can you think of personal examples of this?
Can you remember them all?
Review and Practice - Worksheet
Practice of Fallacies of Irrelevance
1. “I should receive an 'A' in this class. After all, if I don't get an 'A' I won't get the pay increase that I need.”
2. John said, “We should put more money into health and education. Sam responded by saying, “ John, you must hate our country so much that he wants to leave it defenseless by cutting military spending.”
3. “Millions of women are using the new extended care moisturizer.” 4. "If such actions were not illegal, then they would not be prohibited by the
law.” 5. I know I forgot to take out the rubbish. But, nothing I do pleases you. 6. Only an uneducated person would believe that there is a peaceful solution
to this conflict. 7. "You know, Professor Smith, I really need to get an A in this class. I'd like to
stop by during your office hours later to discuss my grade. I'll be in your building anyways, visiting my father. He's the head of the department, by the way. I'll see you later."
Practice of Fallacies of Irrelevance (Answers)
1. “I should receive an 'A' in this class. After all, if I don't get an 'A' I won't get the pay increase that I need.” Appeal to Pity
2. Will said, “We should put more money into health and education. Warren responded by saying, “ Will, you must hate our country so much that you want to leave it defenseless by cutting military spending.” Straw Man
3. “Millions of women are using the new extended care moisturizer.” Bandwagon4. "If such actions were not illegal, then they would not be prohibited by the law.”
Begging the Question5. I know I forgot to take out the rubbish. But, nothing I do pleases you. Red
Herring6. Only an uneducated person would believe that there is a peaceful solution to
this conflict. Personal Attack7. "You know, Professor Smith, I really need to get an A in this class. I'd like to stop
by during your office hours later to discuss my grade. I'll be in your building anyways, visiting my father. He's the head of the department, by the way. I'll see you later." Scare Tactics
Additional Activities
More Practice
0 Choose 1 fallacy of relevance and find an example (video or text).0 Explain why it is a fallacy
0What pattern is it following?0What value of critical thinking does it not display?
0 Explain how it could be improved
0What would be a better way to write this argument?
0 Choose another fallacy0 In groups, write a scenario to create a fallacious argument
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