Logical Fallacies
Logical fallacies are errors in thinking and
writing that result from faulty logic. Watch for
them in the materials that you read; avoid
them in the argumentative papers you write.
The SIX Logical Fallacies
Hasty Generalization
Oversimplification
Either/Or
False Analogy
False Causality
Circular Reasoning
# 1 Hasty Generalization
A hasty generalization is a conclusion based on
too little evidence, suggesting a superficial
investigation of an issue.
TRANSLATED: Someone has jumped
to conclusions by pretending they have
done the research but they are giving
you skewed information instead.
Example of
Hasty Generalization
“The last three times I drove to school I was late
because an old person in front of me was driving
too slow. All old people are slow drivers.”
In an interview, a parent picked from a random
school claims the quality of education in this
country is declining. The evidence she gives is
that both her daughter and her neighbor’s
daughter are doing poorly on standardized tests.
#2 Oversimplification
A Oversimplification ignores the complexities,
variations, and exceptions relevant to an issue.
TRANSLATED: The information you are
given is way too simple…someone
avoided a bunch of other important
factors.
As Einstein said, everything should be made as
simple as possible, but no simpler.
Oversimplification Examples
Political slogans such as "Taxation is theft"
“The question of funding medical research
comes down to this: do we want to heal the
sick and help the injured to recover -- or not?”
“Since the new president took office, the
economy has been improving - obviously he
is doing a good job and is an asset to the
nation.”
#3 Either/Or
The either/or fallacy suggests that only two choices
exist when, in fact, there are more. This type of
thinking is not only illogical but also unfair.
TRANSLATED: They make you think you
only have two options…when, really, there
are many options.
Either/Or Examples
“You're either with us or against us.”
There are only two kinds of politicians:
those interested in their own welfare and
those interested in the welfare of others.
“Math is a tough subject—you either
understand it or you don’t.”
#4 False Analogy
A false analogy is a comparison that is not based
on relevant points of similarity. For an analogy to
be logical, the subjects must be similar in several
important, not superficial, ways.
TRANSLATION: Comparing two things
that don’t have much in common.
False Analogy Examples
The universe is like an intricate watch. A watch must
have been designed by a watchmaker. Therefore,
the universe must have been designed by some kind
of creator.
People are like dogs. They respond
best to clear discipline.
Today’s stock market, just like the stock
market in the 1920’s, seems headed for
trouble.
#5 False Causality
A false causality suggests a cause and effect
relationship between two things (actions), even
though one action simply preceded the other.
TRANSLATION: because one event follows
another, it doesn't follow that one event caused
the other
False Causality Examples
Since the artificial sweetener aspartame
was introduced in 1981, cancer rates have
risen in the United States.
Every severe recession follows a Republican
Presidency; therefore Republicans are the cause of
recessions."
Since hair always precedes the growth of teeth in
babies, the growth of hair causes the growth of teeth."
#6 Circular Reasoning
Circular reasoning fallacy is an argument
based the repetition of an assertion as a
reason for accepting it.
TRANSLATION: Saying something over
and over again (perhaps using different
words) makes people think it’s right.
Examples of Circular Reasoning
“You can’t give me a C. I’m an A student!”
“Richardson is the most successful mayor
the town has ever had because he's the best
mayor of our history.”
This restaurant serves the best food in the
town, because it has the best chef. It has
attracted the best chef because it has the best
reputation. It has the best reputation because
the chef cooks the best food.
“This test is hard because it is so difficult!”
What Fallacy? GAME
A fallacy will be presented.
Use your notes to guess which logical fallacy is
being used!
Write your
answers on the
back of your
Notes.
What Fallacy?
EXAMPLE!!!
“The speed of light can be reached! We didn’t
think that anyone could run a four-minute
mile or that the sound barrier could be
broken, but we eventually did both. It stands
to reason that the light barrier, which some
people don’t think can be broken, will
eventually be reached.”
1. What Fallacy?
Learning to swim is easy because it’s
not a difficult sport to learn.
2. What Fallacy?
“We can either burn the house down and
collect the insurance money or we can
continue living in an unsafe house. Since we
shouldn’t keep living in an unsafe house, we
should burn it down.”
3. What Fallacy?
“I have a right to say what I want,
therefore you shouldn’t try to
silence me”
4. What Fallacy?
"My roommate said her philosophy class
was hard, and the one I'm in is hard, too.
All philosophy classes must be hard!"
5. What Fallacy?
"President Jones raised taxes, and then the rate
of violent crime went up. Jones is responsible for
the rise in crime."
6. What Fallacy?
“We can either go to the river or eat
sandwiches. We’re both hungry, so we
should eat sandwiches and not go to the
river.”
7. What Fallacy?
"Guns are like hammers—they're both tools with
metal parts that could be used to kill someone.
And yet it would be ridiculous to restrict the
purchase of hammers—so restrictions on
purchasing guns are equally ridiculous."
8. What Fallacy?
"Active euthanasia is morally acceptable. It is a
decent, ethical thing to help another human
being escape suffering through death."
9. What Fallacy?
It is claimed by some people that
severe illness is caused by depression
and anger. After all, people who are
severely ill are very often depressed
and angry. Thus, it follows that the
cause of severe illness actually is the
depression and anger. So, a good and
cheerful attitude is key to staying
healthy.
10. What Fallacy?
All people who get straight “A”s have
high I.Q.s
11. What Fallacy?
"Caldwell Hall is in bad shape. Either we tear it
down and put up a new building, or we continue
to risk students' safety. Obviously we shouldn't
risk anyone's safety, so we must tear the building
down."
12. What Fallacy?
All Americans are patriotic.
THE ANSWERS
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
Circular Reasoning
Either/or
Circular Reasoning
Hasty Generalization
False Causality
Either/Or
False Analogy
Circular Reasoning
False Causality
Hasty Generalization
Either/Or
Hasty Generalization