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