Logical Fallacies
How to spot sloppy thinking, dirty tricks, and flamboyant lies
Pointy things go in the
outlet, right?
Oh, look! It’s human nonsense generator,
Donald Trump!
TRUMP! Everybody is
excited about me! Big
crowds, big, big crowds…
the polls…. TRUMP!!!!
Yeah… That really doesn’t make any sense… which reminds me that this is a
good time to talk about logical fallacies!
A flawed argument is called a logical fallacy.
They take several forms
and usually
involve
some
Ha ha
ha! America!
oversight,
generalization,
President
from Sudan?
or purposeful
to
Losersattempt
are FIRED!
mislead. Recognizing
TRUMP!!!
fallacious logic is the key to
discerning good
argumentation from bad.
Right, Donald?
There are dozens of types of fallacies– some are
rooted in erroneous analysis; some are deliberately
misleading efforts.
For our purposes, we’ll look at three different categories:
• Fallacy of relevance
• Fallacy of accuracy
• Fallacy of insufficiency
Fallacies of Relevance
• These fallacies confuse pertinent information with irrelevant details.
They can often be intentionally misleading.
•
•
•
•
•
Red Herring
ad hominem
Faulty Analogy
Appeal to False Authority
ad populum
Fallacies of Relevance: Red Herring
Definition: The speaker
skips to a new and
irrelevant topic in order
to avoid the topic of
discussion.
Examples
We can’t worry about the environment! We’re
at war!!
What do you mean I get an F on this
assignment? I worked sooooooo hard on it!
What do you mean I have to go to jail for
repeatedly driving drunk? It’s soooooo
difficult being famous!
Fallacies of Relevance: Red Herring
Trump vs.
Broccoli
Now, look at this guy. He’s a
little green guy. Bushy guy. I
was negotiating with this little
bushy green guy. I beat him. I
beat his rear end, I tell you.
You know what America thinks
of you? You’re done.
Fallacies of Relevance: ad hominem
Definition: A type of red
herring where the topic is
switched from a particular
topic to the character of
the other speaker. Latin for
“against the man.”
That was
an ad
hominem
attack!
YOUR MOM is
an ad hominem
attack! HA!
Am’I’rite?
Examples
Of course Mr. Rossi would want to give a quiz
on Thursday. He’s a communist!
That’s not an ad hominem attack, you idiot.
Fallacies of Relevance: ad hominem
Trump vs. a
forklift
I know all about forklifts. Very
knowledgeable. They are
thieves and rapists and rapist
thieves. I’m sorry, but there is
no place in America for their
squishy liberalism. They cannot
lift the truth.
Fallacies of Relevance: Faulty Analogy
Definition: A fallacy of
irrelevance where two
things are compared
without an appropriate
basis.
Examples
Because we allow terminally ill patients to use
heroin, we should allow everyone to use
heroin.
Because you allowed Lindsay—who was hit by
an exploding truck and knocked off a cliff into
a live volcano—to hand in her assignment late,
you should allow the entire class to hand in
their assignments late.
Fallacies of Relevance: Faulty Analogy
Trump vs. a
lizard
“He’s a tiny guy and he’s
super low-energy. Like a
little sleeping dragon man.
What I say about dragons?
They’re extinct. You’re
extinct. You stink. Goodbye.”
Fallacies of Relevance: Appeal to False
Authority
Definition: When someone
with no expertise to speak
on an issue is cited as an
authority.
Examples
Dr. McBride diagnosed Brandon as having flesh
eating bacteria.
Vikram says we shouldn’t have an ICE on
Thursday, so we shouldn’t have an ICE.
Fallacies of Relevance: Appeal to False
Authority
Trump vs.
Existentialism
I’ll give you the straight
dope. This is bum talk, this
stuff. Chumps. I’m
America’s boss if I’m
anything, and I say it’s gotta
go! 100%.
Fallacies of Relevance: ad populum
(bandwagon appeal)
Definition: Evidence
essentially boils down to
“everyone is doing it, so it
must be a good idea.”
Examples
"Increasingly, people are coming to believe
that Eastern religions help us to get in touch
with our true inner being. Eastern religions
help us to get in touch with our true inner
being.”
Everyone is selfish; everyone is doing what he
believes will make himself happier. Why
should you feel guilty for seeking your own
happiness when that's what everyone else is
doing, too?
Fallacies of Relevance: ad populum
(bandwagon appeal)
Trump vs. a
humpback whale
“This guy, he’s got no chance
against me. No chance. I’m up in
every poll. Women. Veterans. They
love me. America has heard your
whale song and it’s a bum song,
I’m afraid to say it, it’s a bum song
and I’m going to change America.”
Fallacies of Accuracy
• These fallacies occur when the wrong conclusion is drawn or the
wrong assumptions are made.
• Straw Man
• False Dilemma
• post hoc ergo propter hoc
Fallacies of Accuracy: Straw Man Fallacy
Definition: A speaker
chooses a deliberately poor
or oversimplified example in
order to ridicule and refute
the opponent’s point.
Follow the yellow
brick road? What is
this, a thinly-veiled
allegory for the
American gold
standard?
Examples
"Senator Jones says that we should not fund
the attack submarine program. I disagree
entirely. I can't understand why he wants to
leave us defenseless like that.“
We should have nap class. People don't want
to have nap class because they think it’s lazy.
But they should realize that there are more
important things than work.
Fallacies of Accuracy: Straw Man Fallacy
Trump vs. a
couch
“This guy, he’s squishy, can’t pin him
down. I know what he’s all about. I give
him $4000; he spends it on garbage!
Makes bad decisions, not like I would do
if I were in his shoes. He doesn’t even
own shoes. I say, “where are your shoes,
buddy?” What does he say? Nothing.
Scumbag.”
Fallacies of Accuracy: False Dilemma
Definition: The speaker
presents two extreme positions
as the only possible options
when others, in fact, exist.
Examples
"Either you’re with us or you’re
ag’in’ us!”
America: Love it or leave it!
Fallacies of Accuracy: False Dilemma
Trump vs. a
toothbrush
The red flags are up, my friends.
Red flags. Guy says, “brush your
teeth, or you’re finished.” I say,
“Who are you, this bristle face?”
Look, I’m sorry, but that’s the way
it is. Your breath stinks, and I
would not give you gold or
money. Bristleface is a loser.”
Fallacies of Accuracy: post hoc ergo propter
hoc
Definition: Latin for “after
which, therefore because of
which.” Makes a fallacious
connection between effects
and antecedents. In other
words, suggests correlation
implies causation.
Examples
"Joan is scratched by a cat while visiting her
friend. Two days later she comes down with a
fever. Joan concludes that the cat's scratch
must be the cause of her illness.”
Every time my mother attends a game, it rains.
Therefore, my mother is a Pagan weather
goddess and I must sacrifice a lowing calf as
tribute.
Fallacies of Accuracy: post hoc ergo propter
hoc
Trump vs. a balloon
“The first thing that happens with floaties is
that they want free stuff. I give ‘em free
stuff, a million dollars, 500,000 dollars. Then
what? They got the iPhone, the big screen,
the Ferrari, and they’re eating out of the
trash store. If he wasn’t a bozo, making
things float, maybe he could cut it. He would
be a star. But he’s a yellow gross baby.”
Fallacies of Insufficiency
• Conclusions are drawn without sufficient evidence.
• Hasty Generalization
• Circular Reasoning
Fallacies of Insufficiency: Hasty Generalization
Definition: A claim is made
without sufficient evidence
to prove it.
Examples
"I asked six of my friends what they thought of
the Patriot Act and they liked it. Therefore,
the Patriot Act is popular.”
All of my friends think that a fourth high
school needs to be built. Therefore, the
taxpayers will vote for a fourth high school.
Fallacies of Insufficiency: Hasty Generalization
Trump vs. a
Vespa
Scooter
I saw one of these on the
street. Not from around here,
probably an illegal. I know
how to help him. He needs
four wheels! They come to
America to take our wheels!
Sorry, game over.
Fallacies of Insufficiency: Circular Reasoning
Definition: A claim is
repeated as a way to
provide evidence.
Examples
"You can’t give me a C! I’m an A student!”
The New England Patriots are the best football
team because they’re better than the other
teams.
Fallacies of Insufficiency: Circular Reasoning
Trump vs. The
Horsehead
Nebula
I’ll tell you right now that he’s scared
to debate me. He’s scared to debate
me because I’m frightening. What is
he? A cluster of stars? No class. What
can he say to me? It will come back to
him. I know what a boomerang feels
like in my hand, friend. No. It’s over.
The End
I’m calling it right now:
this PowerPoint is over.
Done-so. Kaput. TRUMP!