Common Logical Fallacies
Logical fallacies are specific types of errors in reasoning. Many of them involve bringing
up something that is irrelevant to the issue at hand.
Instructions: Read this overview of common logical fallacies. As you do so, click on the
textbook page for each fallacy & read that specific section of the page.
Fallacy
1
Ad Hominem
Textbook page: Read the
section titled “Personal
Attacks”
2
Appeal to Pity (a.k.a. Appeal
to Guilt)
Textbook page: Read the very
short section on ”Appeal to
Guilt/Appeal to Pity”
3
Bandwagon (a.k.a. Appeal to
Popularity)
Textbook page: Read the
section titled “Appeal to
Popularity”
Description
Example & Explanation
Attacking the person instead “You can’t take Senator X’s argument about
of problems in the person’s gun control seriously. After all, he cheated
argument.
on his taxes.”
Trying to use pity to
persuade instead of
providing relevant evidence
or supporting points.
Question: Wait, that sounds
like pathos. Does that mean
pathos is a fallacy?
Answer: Appealing to pity is
only a fallacy when the
argument relies on eliciting
pity instead of offering any
substantial support.
“C’mon! Everyone else is
doing it!”
Claiming that something is
true, desirable, or correct
because it is popular.
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If the speaker wants to criticize Senator X’s
argument, they should stay on topic and
point out what’s problematic about the
argument.”
“Professor, I know I didn’t turn in a lot of
assignments and haven’t been
participating, but I really need to pass this
class if I’m going to transfer next fall.”
The fact that the student needs to pass the
class might evoke some sympathy, but it
doesn’t address the actual issue—whether
or not the student has met the
requirements to earn a passing grade.
“9 out of 10 Americans support Proposition
XYZ. It’s obvious that you should, too.”
Proposition XYZ may be popular, but that
doesn’t mean it’s a good proposition or that
this person would benefit from voting for it.
4
False Analogy
(a.k.a. Weak Analogy)
Textbook page: Read the
section titled “Common
problems with assumptions”
5
False Authority (a.k.a.
Testimonial)
Textbook page: Read the
sections titled “False
Authority” and “Testimonial”
6
7
False Dilemma (a.k.a. False
Dichotomy, Either-Or, Black &
White)
Textbook page: Read the
section titled “False
Dilemmas”
Hasty Generalization
(a.k.a. Sweeping
Generalization)
Using an analogy to make a
point when the two things
are not similar enough to be
comparable.
This one isn’t in the book,
but it’s so common that I’m
including it here.
Arguing that something is
true or desirable by
referring to someone—
typically a celebrity—who is
not an authority on the
issue.
Making it seem like there
are only two possible
choices in a situation when
there are other choices.
Jumping to a conclusion
based on limited evidence.
Stereotypes are examples of
hasty generalizations.
Textbook page: Read the
section titled “The evidence
may not be representative”
“Banning plastic bags just because they’re
bad for the environment is stupid. Cars are
bad for the environment but we don’t ban
them.”
Plastic bags are unlike cars in so many
major ways that this is a weak analogy. For
example, we’re typically dependent on cars
to carry out daily activities that are
necessary. Not having cars would cause
major disruptions to society. Conversely, we
have a lot of easy and accessible
alternatives to plastic bags.
“Khloe Kardashian says she got her flat
stomach from drinking this shake, so if you
want a flat stomach, you should order this
shake now.”
Khloe Kardashian is not an expert when it
comes to dieting, fitness, or health, so her
claims lack authority.
“If you’re not a vegan, you obviously hate
animals.”
A person is not limited to being a vegan OR
hating animals. For instance, someone
could eat meat and still love animals or feel
neutrally about animals.
“My Hungarian neighbor is terrible with
numbers, and my Hungarian classmate just
failed Algebra. I guess Hungarian people are
just bad at math.”
The examples of two people don’t prove
that something is true of an entire group of
people.
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8
Misuse of Statistics
[This one isn’t in our
textbook]
9
Red Herring (a.k.a. Smoke
Screen)
Textbook page: Read the
section titled “Common
problems with assumptions”
10
Post Hoc
Textbook page: Read the
section titled “Common
problems with assumptions”
Using statistics to imply that
something is true when the
statistics don’t actually
support that conclusion
Bringing up something else
to distract readers from the
issue at hand. The more
subtly this strategy is used,
the more effective.
Think of smelly fish throwing
dogs off the scent when
they’re tracking someone.
Assuming that just because
one event occurred before
another one, it caused the
latter to happen.
Correlation is not causation
3
“80% of dentists we surveyed recommend
Colgate.”
This makes it sounds like 80% of dentists
surveyed recommend Colgate over other
brands.
Problem 1: The actual survey simply asked
dentists to put a check next to all the
brands they recommend. Therefore, the
survey didn’t show that dentists actually
prefer Colgate over any other brand.
Problem 2: We don’t know how many
dentists were actually surveyed. 80%
sounds like a lot—but if there were only 10
dentists in the survey, that’s just 8 dentists.
“Your Honor, my son could not have been
drunk driving that night. He is the school
valedictorian!”
The fact that the son was valedictorian
sounds good, so it seems relevant at first.
However, his grades have nothing to do
with whether or not he was actually drunk
driving that night, so his grades are really
just a distraction.
“I know that vaccines cause autism because
my child was diagnosed with autism two
weeks after his vaccinations.”
This statement only proves that one thing
happened after something else happened.
The speaker hasn’t provided any evidence
to show that the first thing caused the
second thing to happen.
11
Slippery Slope
Textbook page: Read the
section titled “Common
problems with assumptions”
12
Straw Man
Textbook page: Read the
section titled “Is the
description of the
counterargument fair and
accurate?”
Claiming that a particular
action will lead to
consequences that are more
extreme than the evidence
suggests. Think of a
snowball growing bigger and
bigger as it rolls downhill.
Usually with slippery slope
fallacies, the speaker is
trying to scare the audience
with exaggerations about
what will happen down the
road—and not providing
support the claim.
Twisting/misrepresenting
opposing views so that
they’re easy to defeat.
“Supporting DACA will lead to an
uncontrollable flood of immigration which
will lead to America getting taken over by
foreigners and our economy will be
ruined.”
The speaker is trying to scare the audience
by making it sound like DACA will lead to
catastrophic consequences. However, the
speaker is actually just making big a leap in
logic without providing any support.
“Veganism is stupid because vegans think
animals are better than humans.”
Being a vegan does not equal thinking
animals are better than humans. This
person is misrepresenting what vegans
believe in order to make veganism look bad.
A couple of tips:
⦁
Many of these fallacies have different names. For example, the false dilemma is also
known as the either-or fallacy or the black-and-white fallacy. For this class, you can stick
to the first name listed in this handout.
⦁
Many of these fallacies are closely related and even overlap. For example, red herring
and ad hominem are both fallacies that are used to distract the reader from the issue at
hand. Identifying the flaw in logic is what’s most important.
⦁
There’s not always a clear line between logical reasoning and fallacious reasoning. For
example, both of the following sound like Ad Hominem fallacies because they’re
attacking Candidate X instead of his platform for becoming Mayor. However, if aspects
of his personal history are relevant to his qualifications to become mayor, mentioning
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them may not be fallacious.
Fallacy
Possibly Logical
“Candidate X shouldn’t become mayor
because because he cheated on his wife.”
embezzling $30,000.”
“Candidate X shouldn’t become mayor
he was found guilty of
Candidate X’s cheating on his wife
It’s reasonable to be concerned about a
doesn’t necessarily relate to his
a felony
mayoral candidate who has committed
qualifications to be a mayor.
and stolen a large sum of money.
⦁
Just because an article includes a fallacy, it doesn’t automatically mean the whole
argument is false.
⦁
There are additional fallacies, but these are the ones we’ll be focusing on this semester.
If you’re interested in others, here’s just one of many sites you can check out:
https://www.futurelearn.com/courses/logical-and-critical-thinking/0/steps/9131
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