Common Fallacies - Tamalpais Union High School District

• An error of reasoning based on faulty use
of evidence or incorrect interpretation of
Common Fallacies
•Hasty Generalization
•Faulty use of authority
•Post Hoc or Doubtful Cause
•False Analogy
•Ad Hominem
•False Dilemma
•Slippery Slope
•Begging the Question
•Straw Man
•Two Wrongs Make a Right
•Non Sequitur
•Ad Populum
•Appeal to Tradition
•Faulty Emotional Appeals
Hasty Generalization
Definition: Applying knowledge of a few
examples to a much larger category.
Example: Shane doesn’t like salmon. He
won’t eat any fish.
Faulty Use of Authority
Definition: The faulty use of authority occurs
when individuals are presented as
authorities or experts in fields in which
they are not.
Example: Mazdas are good cars because
Mr. Lavezzo and Ms. Dolan drive them.
Post Hoc or Doubtful Cause
Definition: The arguer infers that because
one event follows another event, the first
event must be the cause of the second.
Example: Anthony drove my car last night.
That’s why it isn’t running well.
False Analogy
Definition: Comparing only similarities
between things, concepts, or situations
while overlooking significant differences
that might weaken the argument.
Example: Playing the violin is just like
playing the cello. They are both stringed
Ad Hominem
Definition: Attacking a person’s ideas or
opinion by discrediting him or her as a
Example: President Obama smoked
marijuana in college and should not be
trusted when discussing the legalization of
False Dilemma/BlackWhite/Either/or Reasoning
Definition: Restricting the complex aspects
of a difficult problem or issue to only one
of two possible solutions.
Example: In high school, you can either
party hard and become popular or stay
sober and have no friends.
Slippery Slope
Definition: If an arguer predicts that taking a first
step will lead inevitably to a second usually
undesirable step, he or she must provide
evidence that this will happen. Otherwise, the
arguer is guilty of a slippery slope fallacy.
Example: If teachers let students use smart
phones during tutorial, eventually teachers will
let students use them during regular classes.
Pretty soon cell phones will always be out during
class time.
Begging The Question
Definition: Assuming that the statement
being argued has already been proven
Example: John should go to prison because
he is guilty.
Straw Man
Definition: The straw man fallacy consists of
an attack on a view similar to but not the
same as the one your opponent holds.
Example: People who support gun control
do not believe in self-defense. They don’t
want you to be able to protect yourself in a
life threatening situation. That’s why they
support gun control.
Two Wrongs Make a Right
Definition: The two-wrongs-make-a-right
fallacy is another example of the way in
which attention may be diverted from the
question at issue.
Example: My parents drink a bottle of wine
every night so it’s all right if I drink a six
pack on the weekend.
Non Sequitur
Definition: Asserting as a conclusion
something that doesn’t follow from the first
premise or premises.
Example: If you don’t bring your children to
Disneyland, they will hate you.
Ad Populum
Definition: Arguers guilty of the Ad Populum
fallacy make an appeal to the prejudices of
the people.
Example: The majority of people like The
Lego Movie so it must be quality film.
Appeal to Tradition
Definition: In making an appeal to tradition,
the arguer assumes what has existed for a
long time and has therefore become a
tradition should continue to exist because
it is a tradition. If the arguer avoids telling
his or her reader why the tradition should
be preserved, he or she may be accused
of failing to meet the real issue.
Example: My family has always owned Ford
cars. My first car will be a Ford.
Faulty Emotional Appeals
Definition: You can recognize fallacious emotional
appeals if they are irrelevant to the argument or
draw attention from the issues being argued or
they appeal to conceal another purpose.
Example: Shane was so upset. He was yelling
and stamping his foot. I though he might break
something. I had to let him go to the eighth
grade bonfire at Muir Beach.