BY JULIE FAULKNER
LOGICAL
FALLACIES
ESSENTIAL QUESTIONS
What techniques to advertisers, writers,
and speakers use to persuade their
audiences?
How can being aware of these techniques
make us more critical thinkers and
digesters of information rather than just
consumers?
WHAT IS A LOGICAL FALLACY?
A logical fallacy is a mistake in
reasoning, a flawed argument used just
to win a debate, a distraction from the
actual argument, or a foundational
weakness in reasoning.
FEAR
FEAR
FEAR
Click to watch an example of appeal to fear.
https://www.youtube.com/watch?v=SfAxUpeVhCg
AD HOMINEM
[LATIN: “TO (AGAINST) THE PERSON”]
Ad hominem is an argument
that attacks the character of
a person rather than his
opinions or arguments.
AD HOMINEM
[LATIN: “TO (AGAINST) THE PERSON”]
Example:
Oprah’s donations to worthy causes
are useless because she can’t possibly
know about poverty as a rich and
arrogant celebrity.
AD HOMINEM = PERSONAL ATTACK
AD HOMINEM = PERSONAL ATTACK
AD HOMINEM = PERSONAL ATTACK
AD HOMINEM = PERSONAL ATTACK
Click the link to watch a video where the speaker employs personal
attack.
https://www.youtube.com/watch?v=AppHOYxpquQ
FALSE DILEMMA/SITUATION
Presents only two choices and forces
someone to choose from the two
choices when in reality there are
plenty more options out there.
FALSE DILEMMA– ONLY TWO CHOICES
Example:
If you drive without car insurance, then you’re an accident waiting to
happen.
Stay protected with Auto Union insurance.
Fa lse ana log ies use com par isons or m etaphors
to re la t e ideas o r s i tua t ions tha t a re no t
rea l l y tha t s im i la r .
*Be sure tha t the two ideas you ’ re com par ing
are rea l l y re la t ed .
FALSE ANALOGY
Example: Students and nails are the same. As it is
necessary to hit nails on the head in order
to make them work, the same must be done
with students.
FALSE ANALOGY
FALSE
ANALOGY
FALSE
ANALOGY
FALSE ANALOGY
• Slippery slope is a conclusion based on the premise that if A happens, then eventually through a series of small steps B, C, D….X, Y, and Z will happen too.
• This basically equates A and Z.
• If we don’t want Z to occur, then A must not be allowed to occur either.
Example:
Parents who do not set a curfew for their children
are setting them up for failure. Their children will
stay out late at night, become involved in self-
destructive activities, develop dangerous habits, get
arrested, and wind up in a life of crime, resulting in
long-term imprisonment.
Example:
If we ban Hummers because they are
bad for the environment, then
eventually the government will ban
all cars; therefore, we should not ban
Hummers.
SLIPPERY SLOPE
SLIPPERY
SLOPE
SLIPPERY SLOPE
Click to watch the Direct TV ad:
https://www.youtube.com/watch?v=u9vbXpMKz6I
NON SEQUITUR
[LATIN: “IT DOES NOT FOLLOW” OR NOT
IN SEQUENCE]
One point or argument does not follow
logically from the preceding one, i.e., no
logical relationship exists between two or
more supposedly connected ideas.
NON SEQUITUR
[LATIN: “IT DOES NOT FOLLOW” OR NOT
IN SEQUENCE]
Example: He has my vote for senator, because
he has the best shirts.
(What does a campaign organization have to
do with qualifications?)
NON SEQUITOR
Click the link to watch a series of commercials from Old Spice that
demonstrate the non sequitor fallacy.
https://www.youtube.com/watch?v=KXuho3eRfh4
FALSE AUTHORITY
F a l s e a u t h o r i t y i s a t a c t i c u s e d m a i n l y i n
a d ve r t i s i n g t h a t p r e s e n t s p e o p l e a s
“ a u t h o r i t i e s ” o n p r o d u c t s o r i s s u e s .
. H o w e ve r, a n a u t h o r i t y i n o n e f i e l d m a y k n o w
n o t h i n g o f a n o t h e r f i e l d .
• B e i n g k n o w l e d g e a b l e i n o n e a r e a d o e s n ’ t
c o n s t i t u t e k n o w l e d g e i n o t h e r a r e a s .
• U s u a l l y c e l e b r i t i e s a n d s p o r t s f i g u r e s a r e u s e d
i n t h i s t a c t i c .
FALSE AUTHORITY Example:
“My uncle is a podiatrist, and he only takes Sweet Valley
daily chewable vitamin C, and so should you.”
•A podiatrist is a foot doctor.
•What does a foot doctor know about the best vitamin
supplement brands on the market?
•A foot doctor would be an authority on products related
to foot care (i.e. corn pads, arch supports, etc.).
POST HOC
LATIN: “OCCURRING AFTER THIS,
THEREFORE RESULTING FROM IT”
Post hoc is a conclusion that assumes a cause/effect relationship between two sequential events. (i.e. If A occurred after B, then B must have caused A.)
A cause and effect relationship between two sequential events; often very unreasonable
POST HOC
LATIN: “OCCURRING AFTER THIS,
THEREFORE RESULTING FROM IT”
Example: “Eating five candy bars and drinking two sodas before a test helps me get better grades. I did that and got an A on my last test in history.” * This ignores other possible causes like how much this student studied or how easy the test was.
POST HOC – FAULTY
CAUSE/EFFECT • A man ate pizza everyday. That man lived to be 100. Eating pizza
everyday will make you live a long life.
STRAW MAN
Misrepresents the context from which a
quotation is taken; putting words or
ideas in people’s mouth/head; creating
a “dummy” or fake or falsified
argument or situation so you can attack
it .
It appears to be a human. It draws the
attention of animals without even really
being anything more than a fixture. It
isn't real, yet the animals are concerned
about it.
STRAW MAN
Bill and Jill are arguing about cleaning out their
closets:
Jill: "We should clean out the closets. They are getting
a bit messy."
Bill: "Why, we just went through those closets last
year. Do we have to clean them out everyday?"
Jill: "I never said anything about cleaning them out
every day. You just want too keep all your junk forever,
which is just ridiculous."
STRAW MAN
"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."
In this example, Senator Jones‘s position is misrepresented as one that
wants to leave the country defenseless. The antagonist is making the
assertion that: "Do not fund the attack submarine program" = "Leave the
country defenseless." However the two statements are not equal, and it
takes more work to argue against the former statement than the latter.
BALL TOSS REVIEW If the ball comes your way, say the definition to the following term:
Straw man
Post hoc
False authority
Non sequitur
Slippery slope
False analogy
False Dilemma
Ad hominem
Appeal to Fear
THANK YOU!
By Julie Faulkner, 2013
www.teacherspayteachers.com/Store/Julie-Faulkner